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Designing an Efficient, Eco-Friendly Toothbrush Project Report

Kashne Kamalanathan Katherine Morgan Miranda Grueiro

Bryan Boyd

March 1, 2012

Enginerds Abstract Our project aimed at designing a toothbrush that maximized efficiency while also being environmentally friendly. In order to satisfy customer needs, we also had to minimize manufacturing costs and maximize durability. In order to figure out the most efficient way to satisfy our design goals, we conducted extensive research in the form of an external search, a patent review, and benchmarking, and then dissected the Oral B CrossAction Rechargeable toothbrush. From our research we found that the most effective brush heads feature a rotating oscillation, nylon bristles, a metal rod that controls vibration, and bristles aligned at 16-degree angles. Additionally, from our dissection we observed how many pieces are found in the toothbrush and how tightly they are manufactured together. Using the information found during research, our group created different design ideas and then chose our final design. We then used drawings and prototypes to create models of our toothbrush.

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1.0 Introduction We have been tasked with designing a powered toothbrush that is more eco-friendly and efficient than the Oral B CrossAction Rechargeable toothbrush. From visual inspections we observed that the toothbrush is composed of many different plastic parts in addition to a rubber grip that covers half of the brush base. We also noted that the toothbrush features an irreplaceable nickel-cadmium battery, replaceable brush heads, and two different buttons to power the brush on and off located in the middle of the brush base. The toothbrush comes with instructions on how to use the brush, replace the brush head, and it states that the battery cannot be recycled. With one our focuses being on designing a more eco-friendly toothbrush, we looked to find a recyclable replacement to the current Oral B battery to add to our design.

The following is the procedure we completed in the design of our toothbrush and the sections of our report where the results are analyzed. Before we could redesign the Oral B CrossAction toothbrush we defined our problem in order to make sure that we solved the correct problem. This was achieved by analyzing who has the problem, what the problem is, when does it occur, where does it occur, and why does it occur. After doing this analysis we formulated our initial problem statement as presented in section 1.1. Our initial problem statement served as a guide of what we should focus on during each step of the design process and after each step we analyzed how we could apply our results to address our problems. The next step was to determine our customer needs by researching and gathering information on the customer’s desired aspects and their weighted importance in our design as seen in section 2. After determining our customer needs we redefined our problem statement in section 3 and performed an external search in section 4. In section 5 we performed an internal search and generated multiple design ideas that would provide solutions to each customer need. Using our analysis from section 5 we analyzed and ranked our ideas before deciding on our final design and its specifications in section 6. Finally in section 7 we concluded our report by reflecting on how our design addresses our customer needs and summarized our project. 1.1 Initial Problem Statement

We were tasked with designing an electrically powered toothbrush that effectively cleans teeth. In addition the toothbrush must be environmentally friendly. The Oral B CrossAction Rechargeable toothbrush is going to serve as a reference to assist us in our design. 2.0 Customer Needs Assessment

To begin our toothbrush design our team needed to do some research and learn about the users’ interests

and needs in a toothbrush. In order for a customer to buy a product, producers must design a product that addresses their customer needs. Therefore, we found out what the customers needs are through a survey answered by 40 people. In the survey we asked potential customers what features they look for when purchasing a new toothbrush. This enabled us to identify which aspects of a toothbrush are most important to the customer and what we must focus on in our design. In the survey we asked for the user’s age, gender and what he/she did and did not like about their current toothbrush. Additionally, we asked what they would change about their toothbrush and the most common answers were durability and comfort. The complete survey with responses can be found in Appendix A. Components of their current toothbrush that consumers like include efficiency, price, and bristle material. The results revealed to us what features are necessary to incorporate in the toothbrush design in order to please the customer. Based off of the responses, the four biggest needs of the customer were found to be efficiency, user-friendliness, eco-friendliness, and physical appearance.

The results from our customer needs assessment were influential in our design. After finding out that the customer desires toothbrushes that are cheap and durable we are going to look to incorporate these traits into our final design. In order to assist in determining the importance of each need we created a weighted list and an analytical hierarchal process chart.

   

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2.1 Weighting of Customer Needs

The individual customer needs that were gathered from the survey were then listed in an initial customer needs list (Table 1). We listed our needs in order to organize them in one place and eventually place them into a hierarchal customer needs list. Listing our needs in an initial customer needs list was also an easy way to get a good idea of what the most important customer needs were without weighting each need and analyzing them further. We collected these needs by pulling out the customer’s answers to what they liked best and what they would change about their toothbrush. The aspects were placed into a table in no specific importance level. The most important features of the toothbrush that the surveys told us were efficiency and cost. 77% who stated that they used a manual toothbrush instead of a power generated one stated how they choose to use a manual simply because it is cheaper than a power brush. 45% said how comfort is one of the most important features when choosing a toothbrush. From these responses we must design a toothbrush that is cheap and comfortable. The needs of the customers are expressed in the table.

 Table 1. Initial Customer Needs List Taken From Survey

Without ranking and weighing the customer needs it is assumed that each need is of equal importance, which is rarely the case. In order to make sure that higher ranked needs are accounted for first during the design, we categorized and ranked each need in a hierarchal customer needs list (Table 2). We categorized our needs based on common themes between the listed needs. The four categories that our traits were organized into were efficiency, eco-friendliness, user-friendliness, and physical appearance. Each category is listed in an outline format in order of importance based on how many responses from our survey stressed that category. We did this in order to find out what our most important customer need is that we must target throughout our design. The order of importance of the categories was determined by the amount of times each category was referenced in the surveys. As a result of 29 of our surveys stressing the importance of cleaning efficiency we placed that as the most important category for us to address in our design. We further organized our data by ranking the importance of each trait within each category. Each trait was ranked based on the amount of surveys that said it was a need. Since 19 surveys listed cleaning teeth and 13 surveys listed cleans hard-to-reach areas, these were our first and second most important traits within the efficiency category. We are going to apply the results of our hierarchal customer needs list by placing the most importance on designing towards efficiency and user friendliness in our design.

Whitens teeth Disposable No charging needed Cleans hard-to-reach areas Portable Comfort Tongue Scrubber Colorful Non slippery grip Large bristle head Replaceable brush head Bristle size Bristle rotation speed Flexibility Light on it to see what you’re Brushing Electronic

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Table 2. Hierarchal Customer Needs List Obtained From Survey

Figure 1. AHP Pairwise Comparison Chart to Determine Weighting for Comparison

Categories

1. Efficiency 1.1 Cleans teeth 1.2 Cleans hard-to-reach areas 1.3 Ability to floss 1.4 Dentist Recommended 1.5 Tongue Scrubber 1.6 Whitens teeth 1.7 Clean mouth feeling 2. User Friendly 2.1 Painless 2.2 Ease of use 2.3 Convenience 2.4 Comfort 2.5 Easy on gums 2.6 Portable 2.7 Non slippery grip 2.8 Replaceable brush head 2.9 Flexibility 3. Eco friendliness 3.1 Battery life 3.2 Durability 3.3 No charging needed 3.4 Disposable 3.5 Electronic 4. Physical Appearance 4.1 Bristles 4.1.a Bristle size 4.1.b Bristle rotation speed 4.2 Colorful 4.3 Light on it to see what you’re brushing

Evaluated Efficiency User  Friendly Eco  Friendliness Physical  Appearance Total  Score WeightEfficiency 1.00 8.00 8.00 8.00 25.00 0.52User  Friendly 4.00 1.00 0.33 3.00 8.33 0.17Eco  Friendliness 0.14 5.00 1.00 7.00 13.14 0.27Physical  Appearance 0.13 0.33 0.14 1.00 1.60 0.03

48.08 1.00

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Figure 2. Analytic Hierarchy Process (AHP) Scale Chart Once we organized all of the features that we needed to include in the redesign of the Oral-B Cross action toothbrush, we used an analytic hierarchy pairwise comparison (AHP) chart to help narrow in on the key aspects to focus on (Figure 1). The AHP chart helped prioritize what important qualities the toothbrush needed to fulfill all of our customer’s needs. Each criterion is compared to one another by rating the importance of the category. Each attribute is compared to another by giving rating the features on a 1-9 scale (Figure 2). Figure 2 displays the scale value meanings for each number from 1-9. The scored were then added up and then computed in to a weighted score. All of the categories were computed to add up to 1.00. The chart showed us that efficiency is the most important aspect of the toothbrush out of all four categories. The weighted scores were then incorporated into a weighted hierarchal table that weighed the needs of the customer using the results from the analytical hierarchy pairwise comparison chart (Table 3). The purpose of this was to give us a better understanding of the importance of each category. Using the numbers from the pairwise comparison chart we were able to see how important each need category is compared to the other areas. From our chart we found that efficiency is almost twice as important as any other need, eco-friendliness and user-friendliness are of similar importance, and physical appearance is not very important. We are going to apply these results by by placing the most importance on efficiency in our design followed by eco-friendliness.

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Table 3. Weighted Hierarchal Customer Needs List Obtained from Survey

3.0 Revised Problem Statement

After compiling our customer needs we redefined our problem to include user friendliness and physical appearance. In addition to designing with emphasis on efficacy and eco-friendliness, we are going to also focus on making the toothbrush user friendly and physically appealing. We are going to continue to use the Oral B CrossAction Rechargeable toothbrush as a reference to assist us in our design. While adding a focus on user-friendliness and appearance, we are going to continue to place an importance on our initial focuses, efficacy and eco-friendliness, in our design. The final design of our toothbrush must contain parts and materials that are user-friendly, eco-friendly, effectively clean teeth, and do not damage the environment. 4.0 External Search

After understanding the revised problem statement, the team conducted an external search in order to find out more information about how competitor’s toothbrushes compare to the Oral B CrossAction toothbrush; research patents containing elements of our design; and research ways to implement efficacy, eco-friendliness, user-friendliness, and appearance into our design.

1. Efficiency (0.52) 1.1 Cleans teeth

1.2 Cleans hard-to-reach areas 1.3 Ability to floss 1.4 Dentist Recommended 1.5 Tongue Scrubber 1.6 Whitens teeth 1.7 Clean mouth feeling 2. Eco friendliness (0.27) 2.1 Battery life

2.2Durability 2.3No charging needed 2.4Disposable

2.5 Electronic 3. User Friendly (0.17) 3.1 Painless 3.2 Ease of use 3.3 Convenience 3.4 Comfort 3.5 Easy on gums 3.6 Portable 3.7 Non slippery grip 3.8 Replaceable brush head 3.9 Flexibility 4. Physical Appearance (0.03) 4.1 Bristles 4.1.a Bristle size 4.1.b Bristle rotation speed 4.2Colorful 4.3Light on it to see what you’re brushing

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4.1 Literature Review

Using sources from the Penn State Libraries and Google Scholar, our group performed a thorough literature review in order to research the powered toothbrush. We were able to find extensive information that allowed us to expand not only our own individual knowledge, but also our ideas for the design of our toothbrush. The literature review was an invaluable piece to the conceptualization process and will enhance our design.

Going into the literature review our group had a basic knowledge of toothbrushes and how they worked, but we did not know which methods of brushing were best or the ergonomics for the toothbrush. Peter Robinson conducted a report on brush heads that discovered only powered brushes with a rotation oscillation, where brush heads rotate one direction and then the other, perform best in the short and long term at removing plaque and gingivae health (Robinson et al., 2009). After reading Robinson’s report, our group is contemplating applying a rotating-oscillation brush head to our design. Oral B conducted a test in response to the inability of bristles to remove plaque at the back of the moth and at approximal surfaces (Beals et al., 2000). The test showed that bristles angled at 16 degrees in a crisscross pattern along the horizontal axis enables more interproximal penetration and cleaning effectiveness that the standard vertical bristle design. In order to improve efficacy we may keep the current design of the Oral B CrossAction toothbrush since they incorporate bristles angled at 16 degrees. Fiona M. Collins found that soft-bristled brushes are more commonly used now because they have been proven to remove more plaque buildup than some other types of bristles (Collins, 2008). In response to her article our group researched the most effective material for soft bristles and found that nylon works effectively at cleaning teeth.

Yungfeng Zhu’s article provided many ergonomic features our group is thinking about incorporating into our design (Zhu, 2011). For our brush handle we are thinking about applying a grip using anti-skid thermoplastic elastomer rubber. The rubber would be in a point like protuberance pattern in order to maximize friction and reduce slipping while positioning the hand at a 45-degree angle. Although Yungfeng Zhu’s article dealt more with the ergonomics of the manual toothbrush, many of the themes can be applied to our design for an electric toothbrush. For example, the S-shape design of the brush neck could allow our toothbrush to maneuver along the inside edges of the mouth, something that could not be done with the traditional straight toothbrush. The Oral B CrossAction design incorporates a straight brush neck; we are thinking about redesigning this neck in order to improve efficacy. Also from his article we may paint the brush white in order for the reader to make the connection on the subconscious level between cleanliness and our toothbrush. In order to relieve compress stress we may make the handle wider at the top and narrower at the bottom. Finally, we are going to apply dimensions for each part of the brush as noted by Zhu in order to maximize efficacy and user-friendliness.

In order to improve the eco-friendliness of our design, we searched for an alternative battery to the nickel-cadmium unrecyclable battery. H.Z. Wang conducted a report on the possibilities of using Hydrogen steam as a source of energy (Wang et al., 2008). Since hydrogen is the most abundant element in the universe this report could greatly enhance our team’s design by informing us of the possibility of using hydrogen to power our toothbrush instead of a nickel-cadmium battery that damages the environment. After reading about the Fuji battery in Mike Hanlon’s article we may use the Fuji battery as a replacement to the nickel-cadmium battery (Hanlon 2009). The soon to be released Fuji EnviroMax batteries are long lasting and have been found to be the most eco-friendly batteries on the market. Another alternative to the nickel-cadmium battery is the 9 Volt nickel-metal hydride (NiMH) batteries (Rechargeable Batteries 2012). These batteries are cheap, eco-friendly, rechargeable, and long lasting.

While conducting a literature review we learned that brush heads that rotate in a rotating oscillation at 16 degree angles with soft bristles clean teeth most effectively, anti-skid thermoplastic elastomer rubber enhances grip, and an S-shaped handle enables maneuverability in and around teeth. We may also look to apply one of the eco-friendly batteries to replace the current nickel-cadmium battery found in the Oral B CrossAction toothbrush. The lessons learned from our literature review will be indispensable to our team as we move towards the next stage of the design process: preliminary design. In addition to a literature review, we also conducted a patent search in order to enhance our preliminary design. 4.2 Patent Search

Upon the conclusion of the literary search a patent search was conducted using Google Patents (Table 4). The objective of the patent search was to find existing solutions to our design goals and inform us of potential designs to incorporate in our toothbrush. The patents of current electronic toothbrush’s bristle design, and

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sustainable toothbrushes yielded key points to include in the redesign of the sustainable brush. In addition, we conducted a patent search to avoid illegally incorporating any competitor’s ideas into our designs. Table 4 shows our results.

Table 4. Art-Function Matrix for Toothbrush Patent Search

Key points of the search were antimicrobial coating, recycled plastic and propylene, flexible bristle heads,

and the controls of the electronic toothbrush. The antimicrobial coating in the first patent was paired with a “V-shape” indentation in the bristles to increase functionality while decreasing materials used for the bristle. The “V-shape” also targets the hard and soft oral tissue increasing successful hygiene. The second patent dealt with a sustainable nonelectric toothbrush. The bristles and the handle are made of a 90% recycled plastic and propylene mix that can also be recycled again. The design of the toothbrush also uses less material while keeping comfort and functionality. The other patent dealing with the rechargeable display focused on ease of controls as well as the average amount of time one spends brushing their teeth. The patent dealing with the brush’s design gives insight into rotary of an electronic toothbrush head, a different style of bristle head then observed in the product given. The flexible bristle head also promotes healthy gums and clean teeth.

We also conducted a patent search on different toothbrush handle and brush head connections. Patent number US5881425 was found for toothbrushes having a handle join the brush head by non-pinching twin beam structures the reasoning for the flexible handle was discovered. This type of toothbrush has two beams connecting the handle to the brush head. The front beam is flat and not flexible while the back beam is flexible allowing the brush head to bend when force by the user is applied. The flexible brush head permits a wider cross-sectional area that the brush can cover to better clean teeth. This double beam can help the brush head reach in the back of the mouth and other hard to reach sections. The front side beam has a wider cross-section area than the back beam to prevent soft oral tissue from entering the gap in between the two beams. The beam structure is molded from a polymeric material. Another method of connection the brush handle to the brush head is having a flexible neck. This style of toothbrush is made with several different materials. The head is made with semi-rigid material in order to adequately support bristles, enabling the bristles to have a firm base of support while cleaning teeth. This prevents the bristles from becoming dislodged and falling in the user’s mouth during brushing. The handle and neck are made with an elastic material that provides comfort to the user’s hand by conforming to their hand. The flexibility helps avoid damage done to the mouth due to excessive brushing pressure exerted by the user’s hand on the handle. These patents were then placed into an Art-Function Matrix (Table 4). In conclusion to the patent search completed on different toothbrush necks; there are different styles of necks, but flexibility is vital for an effective teeth-cleaning job.

Another patent search was done to identify the different materials used for toothbrush bristles. Toothbrushes on the market range from “soft” to “hard” bristle heads. The range of bristles is usually made with a nylon material. The hardness of the bristle is then determined by the diameter of each individual bristle. Each degree of bristle strength is equally effective; the stiffness options are just for user’s preference. Another material typically used is polybutylene terephthalate. This material is generally stiffer than nylon. Polyamides, including nylon, are all used to make bristles. Patent US5320842 stated how nylon and polybutylene terephthalate are mainly used to create tooth brush bristles. After research these two materials have been found to be the most effective for teeth cleaning. In summary, nylon and polybutylene terephthalate are the most widely used materials for toothbrush bristles. All effective toothbrushes use these two materials to increase the efficiency of their products.

While conducting our patent search we found a lot of information that we could apply to our toothbrush design. In order to make our design eco-friendly we may make our handle and brush head out of a 90% recycled plastic and propylene mix that can continually be recycled. A solution to designing a brush that effectively cleans teeth may be to use a flexible brush head with nylon bristles that enable the brush to clean a wider cross-sectional area. Other themes from our patent search that we may incorporate in our design are the use of a semi-rigid material in order to adequately support bristles and a beam structure in order to connect the brush head to the handle.

Function Art Bristles Handle Rechargeable Display

Hygiene US5320842 Design US8032964

Sustainability US5881425 US5881425 Utility US20100281636

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Through researching existing solutions to our design objectives, our patent search provided us with multiple ideas that we may apply to the final design of our product. 4.3 Benchmarking

Upon completing a patent search we continued our external search by benchmarking similar toothbrushes. We chose which toothbrushes to compare based on user comparisons, product features, and competing brands. Our team benchmarked similar toothbrushes in order to compare how each individual toothbrush fulfills our design goals (Table 5). We compared the Oral B CrossAction, Philips Sonicare HX 5351, Colgate 360 Sonic Power, and Supersmile Professional Series II LS45 Advanced Sonic Pulse toothbrushes. We rated the toothbrushes on a 1 to 5 scale, with one being the worst and five the best, on each of our design goals of efficacy, user-friendliness, eco-friendliness, cost, and durability. We rated the products based on customer reviews, dissections, and visual inspections.

Table 5. Benchmarking Four Toothbrushes

Our results showed that the Oral B CrossAction toothbrush is ranked higher than the other toothbrushes

in physical appearance and cleans teeth as well as the Supersmile and Philips. It also got rated highest in terms of user-friendliness along with the Philips and Supersmile. The only toothbrush that addresses our customer’s need of cost is the Colgate toothbrush, which is priced under $10. Although the Supersmile is priced the highest its ability to clean teeth is equivalent to the much cheaper CrossAction and Philips. We are going to apply the results from our benchmarking into our design by applying the traits that made the Oral B CrossAction toothbrush more visually appealing than the others. These traits include a white base with a colored grip. The white base is important to the design because it invokes feelings of cleanliness in the user. Since none of the toothbrushes were rated well in terms of eco-friendliness we are going to have to design a new source of power for the brushes that is disposable without damaging the environment. We are also going to look to apply the bristle material and other aspects of the CrossAction, Philips, and Supersmile that enabled them to earn high ratings in efficacy.

Features Oral-B CrossAction

Philips Sonicare HX 5351

Colgate 360 SonicPower

Supersmile Professional Series II LS45 Advanced

Sonic Pulse

Efficacy 5 5 2 5 User-

Friendly 5 5 4 5

Eco-Friendly

3 2 3 3

Physical Appearance

5 4 1 4

Cost 3 1 5 1 Durability 3 4 2 2

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4.4 Product Dissection

After benchmarking the Oral B CrossAction Rechargeable toothbrush we performed a product dissection on that toothbrush and the Oral B Advance Power 400 electric toothbrush. The purpose in performing a product dissection on these two products was to analyze their parts, manufacturing processes, and cost. Performing a product dissection on both toothbrushes allowed us to compare them to each other and analyze how they address our design goals. We used scissors, screwdrivers, power gauges, and noise meters to analyze each toothbrush part.

The first toothbrush we dissected was the Oral B Advance Power 400 electric toothbrush. First, we tested the sound that it made (74.7 decibels at 1 inch from the motor). We also tested the current that it drew (an average of 0.475 amps under load). From finding the mean current and voltage (3.12 V) we could calculate the power (1.482 milliwatts under load). Using these measurements and the normal lifespan of a battery, we estimated that the batteries in this toothbrush would die after about 30 days.

The second toothbrush we dissected was the Oral B CrossAction Rechargeable toothbrush. The brush is composed of three main parts: the brush head, the brush base, and the internal features. The head and base are made out of dense plastic that is neither easily breakable nor flexible. On the base there is a rubber grip that provides support to prevent the brush from slipping out of the user’s hand. In addition to being made of plastic, the brush head has nylon bristles that are one cm long. When the brush is turned on through a button on the base, the bristles vibrate in order to clean teeth. The vibration movements are a result of an internal rod that is connected to the bristles. Also on the inside of the brush is a nickel-cadmium battery, which provides power to the aluminum motor when the brush is turned on. The motor then vibrates the metal rod that vibrates the bristles. Pictures from our design lab are referenced in Appendix A.

We conducted several tests of Oral B CrossAction toothbrush. First, we tested the sound that it made (85.9 decibels at 1 inch from the motor). We also tested the current that it drew (an average of 0.475 amps under load). From finding the mean current and voltage (0.9 V) we could calculate the power (0.4275 milliwatts under load). Using these measurements and the normal lifespan of a battery, we estimated that the battery would die after about 30 days.

During our dissection we noted several similarities and differences between the two toothbrushes. The first difference is that the noise level of the Advance Power 400 is quieter than the CrossAction. Compared to the Advance Power 400, which used AA alkaline batteries, the CrossAction uses a nickel-cadmium rechargeable battery. As a solution to user friendliness, we may incorporate alkali batteries into our design in order to make it quieter. The toothbrushes were similarly manufactured. Both toothbrushes are produced with parts perfectly molded to fit both internally and externally. Additionally both toothbrushes were well manufactured, making it difficult and time consuming to dissect our toothbrushes. On the inside of the toothbrush there were plastic pieces and metal rods designed to secure parts internally. In addition to being difficult to remove its parts, the Oral B CrossAction toothbrush is also manufactured with measures to protect it from water damage. There are rubber seals to prevent water damage to the motor and battery, an idea that we may apply to our toothbrush. In total there were 17 parts of the toothbrush all of which were relatively inexpensive.

This dissection was beneficial to our design and we may incorporate ideas from both toothbrushes into our final design. The dissection allowed us to see the internal parts of the toothbrush, which helped us understand how the toothbrush actually works and the significance of power to help effectively clean teeth. We may design our toothbrush to include plastic pieces internally in order to secure parts. It may also enhance our design if we include alkali batteries and rubber water seals to enhance user friendliness and durability of the toothbrush. Through our dissection, we came up with new ideas to improve our design. 4.5 Design Target During the design process, we decided that our target was to create the most efficient, eco-friendly, and durable electric toothbrush. In our literature review we learned that brush heads that rotate in a rotating oscillation at 16 degree angles with soft bristles clean teeth most effectively, anti-skid thermoplastic elastomer rubber enhances grip, and an S-shaped handle enables maneuverability in and around teeth. Our patent search inspired us to create an eco-friendly handle and brush head out of a 90% recycled plastic and propylene mix that can continually be recycled. We also decided that to effectively clean teeth, the brush head should be flexible with nylon bristles that enable the brush to clean a wider cross-sectional area. After benchmarking, we decided to apply traits, which made the Oral B CrossAction toothbrush more visually appealing than other toothbrushes with features that included a

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white base with a colored grip strip. Since none of the toothbrushes were rated well in terms of eco-friendliness we are going to have to design a new source of power for the brushes that is disposable without damaging the environment. We are thinking about using the nickel-metal hydride rechargeable battery from our literature review as an alternative since it is eco-friendly and efficient. Our external search influenced our design and provided solutions to our design goals.

5.0 Concept Generation and Selection

After completing an external search, the team moved to internal searches. Our goal was to generate as many ideas as possible for the design of our toothbrush based off of the data collected from section 4. The Enginerds used idea generation sketches and a morphological chart to aid in developing and selecting the best design ideas that met our objectives. 5.1 Concept Generation

After completing the customer’s need analysis, the team got a better understanding of the wants of the consumer. Using a combination of internal and external searches, the team compiled a list of target areas that can be used when redesigning an electronic toothbrush. Each individual team member then took time to generate ideas on their own in an Idea Generation Map (Figure 3). Each member created design ideas for the brush head design, power generation, human factors body design, and energy mechanism for brush head. At the end of this step we had acquired 8 different ideas for the brush head design, power generation, human factors body design, and energy mechanism for brush head. This initial brainstorming was very beneficial to our final design. Many creative, innovative ideas that had not been previously thought about were brainstormed during this step, giving us more innovative ideas to choose from when it came time to select our final design. Some of our more creative ideas that were generated include using UV rays to power our toothbrush (Concept 1), a brush that forms to your hand (Concept 3), a brush head that provides flossing while brushing (Concept 8), and a toothbrush that you place on your finger (Figure 3). Our most creative ideas are listed below.

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Figure 3. Idea Generation Using an Idea Generation Map to separate these ideas proved to be the most aesthetically pleasing as well

as best functioning. This technique makes the train of thought behind each idea easily flow. After filling out the Idea Generation Map we then selected the top four ideas for each design aspect and put them in a morphological chart (Figure 4).

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Figure 4. Morphological Chart for Idea Generation

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The purpose of the morphological chart was to separate our best ideas from our idea generation map. We chose which ideas to put in our morphological chart based on cost, how well they fulfill our design objectives, and reasoning to get rid of impractical ideas. We placed sixteen total ideas in our chart, four ideas for brush head design, body design, power generation and energy mechanics. Having all of our best ideas arranged together allows us to select the best ideas from each part to combine together to make our final design. Using the AHP chart (see section 2) we determined the importance of each feature highlighted in the designs. We determined that the most important features for the brush to have were efficiency and eco-friendliness. To address efficiency we choose brush head designs that moved in rotating oscillations, as well as up and down motions. We also redesigned the bristle configurations of the brush head to include bristles aligned at 16 degrees. For power generation we selected ideas based on how eco-friendly they were. These include a recyclable rechargeable battery with a smaller charging platform, disposable alloy batteries, and UV rays. We also stressed eco-friendliness when choosing which human factors body design ideas to place in our morphological chart. Our ideas include using less materials and recyclable plastics for our body, an S-shaped handle, grip strips, and a body that is made up of entirely rubber that molds to the user’s hand to enhance grip. Finally, our energy mechanism designs include using gears, a metal rod, a microchip, and a motor next to the bristles to power the brush head. Using a morphological chart enabled us to narrow down our ideas into the ones that best achieve our design goals. Ideas that did not fulfill our goals of user-friendliness, efficacy, environmental-friendliness, and physical appearance were disregarded and eliminated from our final design ideas. After narrowing our ideas into our top 16, we used a pugh chart to compare ideas based on how well they addressed our design objectives.

6. Concept Selection

In order to further narrow down our ideas, we developed sixteen Pugh Charts to analyze our ideas from our morphological chart and to assist in the selection of our final design (Reference Appendix B for all sixteen charts). The purpose of the Pugh Chart is to evaluate and select concepts in an orderly fashion, reducing the likelihood of selecting wrong concepts or eliminating promising ones. The technique allows the relative comparison of concepts against a list of evaluation criteria. We made our Pugh Charts by comparing one design idea within one of the categories in the morphological chart against the rest of the ideas from that category. For example we compared one of the brush head designs against the other three brush head designs. One of the four ideas generated for the brush head is chosen to be “blacked out” in the chart, showing that that idea is the one being compared against. The goals of our design, eco-friendliness, efficiency, user-friendliness, and physical appearance, are placed across the top of the chart as our comparison criteria. The comparison process is completed by using a “1” if the idea being compared to the “blacked out” idea is a better choice within the characteristic. A “0” is if they are similar and a “-1” is if the idea is a worse choice. We had found different “weights” for the characteristics by using an Analytic Hierarchy Process seen in Figure 1. We used them to multiply by the 1 ,0, or -1 to then rank the ideas in order from highest rank to lowest. We made a chart for each idea from the morphological chart to give us a total of 16 morphological charts.

We completed these charts in order to weigh and rank each idea based on how well it provides a solution to our design goals. Through completing the sixteen different charts, we found that the microchip would be the best energy source, a rechargeable battery would be the best power source, the floss-enabled brush head would be the best brush head structure, and the angled handle would be the best body design construction. These findings helped us formulate our final product design.

After meeting and discussing the results of our Pugh Chart we decided upon our final design. Our design is going to incorporate a rechargeable battery, a floss-enabled brush head, and an angled brush handle. The one area where we are not going to take the design that was rated first in our Pugh Charts is the energy source. After further researching the microchip we found it to be too expensive to add to our design. The chips cost an average of $40 per chip plus an additional cost to program. With one of our customer needs being cost, we decided to use the next highest rated energy source from our Pugh Charts, a metal rod. They are much cheaper while still satisfying our design goals. Since we our brush head is going to operate in a rotation oscillation our design is also going to need to include gears in order to function the rotation.

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6.0 Final Design

Using our design ideas from our concept selection, we finalized our design in order to decide upon the details of our final design and in order to make prototypes and drawings to visualize what our toothbrush will look like.

Our brush head is going to power our bristles in a rotating oscillation. We found this brush head design to satisfy our objectives best in the pugh charts and literature review. The head is going to be in the shape of an oval with the bristles separated into 3 different areas to maximize maneuverability and efficacy. The entire brush head is going to be 3.8 cm in length and 1 cm wide with each bristle section being 1.25 cm long and 1 cm wide. We chose these dimensions based off of the dimensions we found for the Oral B CrossAction toothbrush during our product dissection. We designed our head to be the same length as the Oral B toothbrush since it provides maneuverability and cleaning efficacy. In order to maximize efficacy each bristle area will rotate differently. Using the results of our literature search, we are going to make our bristles out of nylon and aligned in a crisscross pattern at 16 degrees along the horizontal edge of the brush head. The nylon bristles are going to be 1 cm long by .1 cm wide. In order to provide a flossing effect while not discomforting the user’s gums, the bristles positioned on the exterior of the brush head are going to be made out of polybutylene terephthalate. In order to enable the polybutylene terephthalate bristles to provide a flossing effect they are going to be 1.25 cm long by .1 cm wide. This added length will enable the bristles to maneuver in between teeth to remove plaque and other buildup.

The interior of our brush is going to contain a metal rod, gears, a motor, a battery, a plastic casing, and a rubber seal. Behind our brush head three gears are going to be located. The gears are going to be connected to a metal rod. The rod is going to be 7 cm by 1/10 cm and made out of steel. The rod is going to have to be curved in order to fit into position with our angled handle. At one end the metal rod is going to be connected to the brush head and at the other end it will be connected to the motor. The motor will be connected to the battery through two small wires that connect the bottom of the motor to the top of the battery. Our toothbrush will use the same plastic pieces to hold the battery and motor into place as the CrossAction toothbrush because the pieces are cheap to manufacture. In order to make our toothbrush eco-friendly we are going to use the nickel-metal hydride battery. It is recyclable, long lasting, and can be manufactured cheaply. Additionally on the interior of our toothbrush we are going to place the same rubber seals as the CrossAction toothbrush to protect the battery from water damage.

We are going to apply the results of our pugh chart and design our brush with an angled handle. From the literature review we found that an S shaped handle maximizes ergonomics for a manual toothbrush. However, it is not logical for an electronic toothbrush’s handle to be completely S shaped because the battery and other parts from the interior would not fit in it. Therefore we are going to incorporate the S shape’s ergonomic benefits into our design by featuring a slightly curved handle. In addition to the curved handle we are going to apply the grip strips idea to our design in order to provide grip and user-friendliness. The grip strips are going to be made out of anti-skid thermoplastic rubber. Instead of using an entire grip across the body of the toothbrush like the CrossAction we are going to use 4 strips that are one cm long by one cm wide in order to minimize materials and waste. These strips use seven times less rubber than the grip on the CrossAction toothbrush and therefore our grips are more environmentally friendly.

The dimensions of our brush base are going to be the same dimensions as the CrossAction toothbrush. User reviews of the Oral B CrossAction toothbrush’s size were positive and users commented that its dimensions maximized their ability to maneuver the brush head inside the mouth. These dimensions will increase brushing efficiency by allowing the user to continue brushing in hard to reach areas and maneuvering the toothbrush around the mouth. Therefore the dimensions of the entire brush are going to be 19.5 cm x 2 cm. In order to make it eco-friendly the brush is going to be made of a 90 % recycled plastic and propylene mix. Not only is our brush manufactured using recycled materials, but also when it is disposed of it can be recycled again and used in future plastic products. To power on our toothbrush we are going to have one button with a 1 cm circumference located 10 cm from the bottom of the brush base. Using one button instead of two minimizes user confusion as to which button is responsible for turning it on and off and therefore maximizes user friendliness. In order to make our toothbrush physically appealing we are going to make the toothbrush white with the grip strips being light blue. We are going to make the brush white due to our findings in our literature search from Zhu’s article that found toothbrush sales of white toothbrushes to be the highest. We are going to design our grip strips to be light blue, the same color as the grip in the Oral B CrossAction toothbrush, due to overwhelmingly positive user reviews about the color of the CrossAction toothbrush.

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In terms of accessories we are going to design a brush head cover similar to the one on the CrossAction. This prevents the bristles from being contaminated with bacteria from the air and keeps the brush head clean. The cover is going to be made out of the same recyclable plastic as the rest of the brush and be 7.5 cm x 1 cm. 6.1 Design Drawings, Parts List, and Bill Of Materials After finalizing our design we created visual models and prototypes to help illustrate our designs. The purpose of creating prototypes is to get evaluation and feedback and it allows stakeholders to see and interact with the product better than they would be able to with a drawing. We created visual models using solidworks (Appendix C) and the RipRap printer to make a scale-model prototype. Using Solidworks we were able to create an isometric view of our toothbrush assembly with the exact dimensions (Figure 5). This allowed us to see exactly what our toothbrush looked like and to fix any potential errors. In Appendix B we also made solid works models of important parts to showcase their functions. In order to calculate the total cost of production and to list the materials in the toothbrush we also created a bill of materials (Appendix D). The total cost to manufacture our design is $7.82.

Figure 5. Isometric View of Final Design

6.2 How Does It Work? First, in order to power the toothbrush the user must press the on and off button. By pressing the button it will send a signal to the rechargeable battery to release energy and start powering the motor. The motor will oscillate a metal rod attached up and down. There are three gears in the brush head connected to each other. The metal rod is configured to the bottom gear. Each gear is responsible for the rotating oscillation of one section of the bristles. While the rod is in motion, it causes the bottom gear to start turning. This triggers the other two gears to move in opposing directions as the source of movement for the bristles. The rotating oscillation motion of bristles paired with

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the slight angle of the bristles makes for optimal teeth cleaning. Once the user is finished cleaning their teeth, the on and off button can be pressed again to disconnect the energy signal from the battery to the motor. 7.0 Conclusions After creating the final design of the product, our team successfully addressed our original product needs of efficacy and eco friendliness in addition to our customer needs of user-friendliness and physical appearance. Using the Oral B CrossAction toothbrush as our model, we designed our toothbrush to be eco-friendly, user-friendly, efficient, and physically appealing. Some of the design features that provided solutions to our design goals include three rotation oscillation brush heads with nylon bristles angled at 16 degrees for efficacy, an anti-skid thermoplastic rubber grip for user-friendliness, a white-glossy exterior for physical appearance, and for eco-friendliness using 90% recycled plastics for our brush base. Unique components in our product include a curve shaped handle and bristles designed for flossing. The features in our toothbrush fit all of our customers’ needs and design goals and would be a competitive product in the toothbrush market.

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Works Cited

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evaluation of a new toothbrush with a novel brush head design.” Pubmed.gov. American

Journal of Dentistry (2000): 5A-14A. Web. 1 February 2012.

Biesbrock, Aaron. “The Clinical Effectiveness of a Novel Power Toothbrush and Its Impact on

Oral Health.” The Journal. 15 May 2002. Web. 31 January 2012.

Cai, Heng. Holerca N. Mariah. Chen, Arthur. Affitto, Van Canady. John. “Silicon modified

polyamide Material Useful for Oral Care.” 2003. Web. 1 February 2012.

Collins M. Fiona. “Biofilm Formation, Identification and Removal.” www.ineedce.com.

Publication. 2008. Web. 31 January 2012.

Dirksing S. Robert. “Toothbrush Having Handle Joined Toothbrush Head by Non-Pinching

Flexible Twin Double Beam.” The Proctor & Gamble Company. 1992. Web. 1 February

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Gizmag. 5 January 2009. Web. 29 February 2012.

O’ Halloran, James. “Toothbrush with Flexible Neck.” Radius Inc. 1998. Web. 1 February 2012.

"Patent US8032964 - Brush Section for an Electric Toothbrush - Google Patents." Google. Web.

01 Feb. 2012.

“Patent US5320842 - Polymeric Particles for Dental Applications - Google Patents." Google.

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"Patent US5881425 - Recycled and Recyclable Toothbrush Having Bristle and Handle

Configurations ... - Google Patents." Google. Web. 01 Feb. 2012.

Penick, Catherine. “Power Toothbrushes: a critical review.” onlinelibrary.wiley.com. Wiley

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Online Library. 2004. Web. 31 January 2012.

“Rechargeable Batteries-Nickel Metal Hydride- NiMH.” Green Batteries. 2012. Web. 29

February 2012.

Robinson, Peter, Scott A. Deacon, Chris Deery, Mike Heanue, A. Damien Walmsley, Helen V.

Worthington, Anne- Marie Glenny, and Bill C. Shaw. “Manual vs Powered

Toothbrushing for Oral Health.” The Cochrane Library. 21 January 2009. Web. 31

January 2012.

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Yankell, SL, CM Barnes, X Shi, and J. Cwik. “Laboratory efficacy of three compact

toothbrushes to reduce artificial plaque in hard to reach areas.” Pubmed.gov. American

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Applied Mechanics and Materials 121-126 (2011): 622-626. Web. 1 February 2012.

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Appendix A. Dissection Pictures

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Appendix B. Pugh Charts

ENERGY Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Gears Metal Rod 1 1 0 0 0.69 2 Micro Chip 1 1 -1 0 0.42 1 Motor in neck

1 -1 -1 -1 -0.05 3

ENERGY Efficiency User

Friendly Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Gears -1 -1 0 0 -0.69 2 Metal Rod Micro Chip -1 1 0 0 -0.35 1 Motor in neck

-1 -1 0 -1 -0.72 3

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ENERGY Efficiency User

Friendly Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Gears -1 1 1 1 0.05 3 Metal Rod 1 1 0 1 0.72 1/2 Micro Chip 1 1 0 1 0.72 1/2 Motor in neck

ENERGY Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Gears -1 -1 1 0 -0.42 2 Metal Rod 1 -1 0 0 0.35 1 Micro Chip Motor in neck

-1 -1 0 -1 -0.72 3

POWER Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Rechargeable AA Batteries 0 -1 0 0 -0.17 2 Heat 0 -1 1 0 0.1 1 UV -1 -1 1 0 -0.42 3

POWER Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Rechargeable 0 1 -1 0 -0.1 2/3 AA Batteries 0 1 -1 0 -0.1 2/3 Heat UV 0 0 0 0 0 1

POWER Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Rechargeable 0 1 0 0 0.17 1 AA Batteries Heat 0 -1 1 0 0.1 2 UV -1 -1 1 0 -0.42 3

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POWER Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Rechargeable 1 1 -1 0 0.42 1/2 AA Batteries 1 1 -1 0 0.42 1/2 Heat 0 0 0 0 0 3 UV

BRUSH HEAD

Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank 360 Degrees Triangle 1 0 1 1 0.82 1 Rubber 0 0 1 0 0.27 3 Flossing 1 0 1 0 0.79 2

BRUSH HEAD

Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank 360 Degrees -1 0 -1 -1 -0.82 3 Triangle Rubber 0 0 0 0 0 2 Flossing 1 0 0 0 0.52 1

BRUSH HEAD

Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank 360 Degrees 0 0 -1 0 -0.21 3 Triangle 0 0 0 0 0 2 Rubber Flossing 1 0 0 0 0.52 1

BRUSH HEAD

Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank 360 Degrees -1 0 -1 0 -0.79 3 Triangle -1 0 0 0 -0.52 1/2 Rubber -1 0 0 0 -0.52 1/2 Flossing

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BODY DESIGN

Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Rubberized Grip

Angled Handle

1 0 1 0 0.79 1

Molded Handle

0 0 0 -1 -0.03 3

Grip Strips 0 0 1 1 0.30 2

BODY DESIGN

Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Rubberized Grip

-1 0 -1 0 -0.79 3

Angled Handle

Molded Handle

-1 -1 0 -1 -0.72 2

Grip Strips -1 0 0 0 -0.52 1

BODY DESIGN

Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Rubberized Grip

0 0 0 1 0.03 3

Angled Handle

1 1 0 1 0.72 1

Molded Handle

Grip Strips -1 0 0 0 -0.52 2

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Appendix C. Solidworks Drawings

BODY DESIGN

Efficiency User Friendly

Eco-Friendly

Physical Appearance

Ideas 0.52 0.17 0.27 0.03 Weight Rank Rubberized Grip

0 0 -1 -1 -0.30 2/3

Angled Handle

1 0 0 0 0.52 1

Molded Handle

0 0 -1 -1 -0.30 2/3

Grip Strips

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Appendix C. Bill Of Materials

Part Material Dimension Quantity Cost Bristle cover 90% recycled plastic

and propylene mix 7.5 cm x 1 cm 1 $0.05

Bristles Poly butylene 1 cm x 1/1000 cm 6000+ >$0.01 Handle 90% recycled plastic

and propylene mix 15 cm x 2 cm 1 $0.70

Rubber grip Anti-Skid thermoplastic rubber

2 cm x 3 cm 4 $0.70

Rechargeable battery Nickel metal hydride NiMH AA 2500 mAH

1 $2.79

Brush head 90% recycled plastic and propylene mix

3.80 cm x 1 cm 1 $0.20

Battery Cover 90% recycled plastic and propylene mix

7.00 cm x 1.90 cm 1 $0.10

Metal battery cover strip

Steel 5.00 cm x 0.32 cm 2 $0.01

Rechargeable Battery Pack

90% recycled plastic and propylene mix

5 cm x 5 cm x 3.8 cm

1 $0.05

Copper Wire Copper 650 cm x 1/100 cm 1 $0.16 Wire Holder 90% recycled plastic

and propylene mix 1 cm diameter 1 $0.07

Metal rod Steel 7 cm x 1/10 cm 1 $1.20 Springs Aluminum 0.32 cm x 1.3 cm 2 $0.05 Plastic interior 90% recycled plastic

and propylene mix 10 cm x 1.3 cm 1 $0.10

Brush head casing 90% recycled plastic and propylene mix

1 cm x 1cm 1 $0.02

Motor Metal and 90% recycled plastic and propylene mix

5 cm x 1 cm 1 $1.50

Rubber seals Performance rubber 1.5 cm diameter 2 $0.10