ECE5320 Mechatronics Oxygen Sensor 3/11/2010 Prepared by: Carlos D. Guzman Dept. of Electrical and Computer Engineering Utah State University E: [email protected]

ECE5320 Mechatronics

Oxygen Sensor

3/11/2010

Prepared by: Carlos D. Guzman

Dept. of Electrical and Computer Engineering Utah State University

E: [email protected] ; T: (435)890-5780;

W: http://mechatronics.ece.usu.edu

03/11/10 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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Outline – Reference list– To explore further– Overview – Major applications– Basic working principle illustrated– Types of oxygen sensors– Oxygen Sensors and the Industry– Applications


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Reference list• http://www.globalw.com/products/wq401.html

• http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=Oxygen.htm&ID=531

• http://www.vernier.com/probes/do-bta.html

• http://www.eidusa.com/Theory_DO.htm


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To explore further

•http://en.wikipedia.org/wiki/Oxygen_sensor •http://www.stevenswater.com/catalog/products/water_quality_sensors/manual/DO1200.pdf •http://www.eutechinst.com/techtips/tech-tips15.htm

Overview• Oxygen sensor: an oxygen sensor is a devise used

to measure the oxygen concentration a measured gas or liquid.



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Major applications

•Automotive: Measure the oxygen concentration on the exhaust of internal combustion engines. •Oxygen liquid: Measure the oxygen concentration on desired liquid, where oxygen concentration is critical. Ie. Beer manufacturing. http://www.directindustry.com/industrial-manufacturer/oxygen-sensor-71701.html


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Major applications

•Medicine: measure oxygen concentration in the blood or any controlled breathing device.

http://www.buckeyemedical.com

Basic Working Principle


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•There are many different principles used to measure oxygen concentration with a sensor. The most common used method is the “Dumb-bell” sensor. In this method, there are used two nitrogen filled spheres compressed by a dumb-bell.

www.delta-f.com



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•The gas passes through the sensor, and due to the paramagnetic properties of the oxygen, it strengthens the magnetic field inside the sensor. The nitrogen spheres has the opposite polarity of the magnetic field and they forces the dumb-bell to rotate with a specific pressure proportional to the amount of oxygen contained in the gas or liquid.

http://www.delta-f.com



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•When the dumb-bell starts to rotate a potential difference is generated at the photocell of the moving dumb-bell. •Because of the movement, vibration it is no desired because of measurement variations. •To avoid such variations, a mirror is used to reflect a bean of light proportional to the dumb-bell movement, and such reflection converted to a small signal voltage to represent the amount of oxygen measured.

http://i.ehow.com

Types of Oxygen SensorsThere are many different method used to measure

oxygen concentration in a gas of liquid sample. Regularly used method are mentioned bellow:

• Electrochemical sensor: Using electrolyte components works as a battery or current source, varying depending on the oxygen concentration through it.

• Partial pressure sensor: Mainly used for medical or diving purposes.


Type of Oxygen Sensors


• Zirconia sensor: Used for flue gas analices.

www.drdaq.com

http://unit.aist.go.jp/amri/group

Oxygen Sensors & the IndustrySince many years ago, measurement of oxygen concentration during manufacturing process have become one of the most noticeable necessities in the industry. To satisfy such necessity the dissolved oxygen sensor became a priority.


http://www.sensorex.com

Dissolved Oxygen SensorDissolved Oxygen (DO) is a term used to refer to the measurement of the amount of oxygen contained in a unit volume of water.

To obtain such measurement is used the dissolved oxygen sensor which provides one of the most accurate oxygen concentration measures.


http://www.broadleyjames.com/sensor-DO-images

Dissolved Oxygen Sensor PricipleThe measurement of the oxygen concentration with that kind of sensor it is not obtained directly by mg/l or ppm, but by the measurement of the partial pressure of oxygen in the water. The pressure of the water is highly dependent in salinity and temperature.


http://image.tutorvista.com/content/respiration-animals/oxygen-concentration-water-blood.jpeg

Dissolved Oxygen SensorThere are two principal technique used to measure oxygen concentration using DO sensors.

• Galvanic: probe are more stable and more accurate at low level oxygen concentration.

• Polarographic: less accurate and the probe needs to be recharged every week of heavy use.


Diffrences Between the two technologies• Galvanic probes include a sensor with two dissimilar

metals to produce a current required for measurement. The sensor has zinc or lead anode, silver cathode, and potassium hydroxide electrolyte. Galvanic probes do not require warm-up time.

• Polarographic probes have polarographic sensors with silver anode surrounded by gold or platinum cathode. This type of probe is also called the "Clark cell". Power is supplied by the meter or other external battery source. Requires 15 to 30 minutes warm-up time.


Selection Guide• Submersible or BOD probes. Submersible probes are

ideal for field use while the BOD probes, available for certain meters, are more appropriate for laboratory use.

• Waterproof housing. Meters range from indoor use, to splash proof, to submersible.

• Automatic barometric pressure compensation. The solubility of oxygen decreases with an increase in altitude (or reduction of atmospheric pressure). Some meters have a built-in barometer to make this adjustment automatically.


Selection Guide• Manual barometric pressure compensation.

Meters allow you to enter the barometric pressure manually.

• Salinity adjustment. As the salinity of the solution increases, the solubility of oxygen decreases. Meters may allow the user to enter the salinity value of their liquid, then compensate accordingly.


Selection Guide• Temperature compensation. As the temperature of a

solution increases, the oxygen solubility decreases. Meters may provide automatic temperature compensation to ensure accurate readings.

• Memory capabilities. Meters may store readings in memory for downloading to a computer or a recorder.

• Replaceable membranes/caps/modules. Replaceable membranes are generally more cost-effective but are more time-consuming. Membrane modules are ready-to-use but cost a little more.


Dissolved Oxygen Sensor ApplicationsDissolved oxygen measurements are used to monitor processes where oxygen content affects reaction rates, process efficiency, or environmental conditions:

• Waste water treatment

• Wine production

• Bio-reactions

• Environmental water testing


Documents

ECE5320 Mechatronics Oxygen Sensor 3/11/2010 Prepared by: Carlos D. Guzman Dept. of Electrical and Computer Engineering Utah State University E: [email protected]