P16104Microfluidic Spectroscopy for

Proteins within CubeSats

Customers: Dr. Lea Michel, Dr. Dorin PatruFinal Presentation – March 10, 2016

Project Background – CubeSats

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• Greatly reduced cost allows for wide variety of research

• Off the shelf hardware is cheaper and quicker to develop compared to conventional space equipment

• More and more Universities and groups are developing CubeSat projects

Project Background – CubeSat Bioresearch

• GeneSat-1 (2006) – Provided life support for bacteria (E. coli) and contained onboard sensors and optical systems for detecting proteins that indicate specific genetic activity

• PharmaSat (2009) - Measured the influence of microgravity upon yeast resistance to an antifungal agent

• O/OREOS (2010) – SESLO and SEVO experiments• Space Environment Survivability of Live Organisms - Measured long term

survival, germination, and growth responses, including metabolic activity of bacteria

• Space Environment Viability of Organics - Monitor stability and changes in four classes of organic matter exposed to space conditions

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Customer Requirements

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Engineering Requirements

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Microfluidic Design

Preliminary - PDMS Wells & Proteins

• Keep lyophilized protein and reagent separate until mixed• Selected Bovine Serum Albumin (BSA) with Phosphate Buffered Saline (PBS)• Easily accessible and commonly used in research

• Initially two wells, improved to three wells • Considered variables

• Height• Volume• Flexibility• Total device size (width, length)

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Intermediate - PDMS Wells & Proteins

• Improved design to have minimal height for solenoids• Reduced volume of reagent and mixed solution • Channels spaced appropriately for solenoids• Problems with design

• Bubbles when mixing • Leaking

• Development of miniature wells for testing purposes• Held single, premixed solution• Testing 3-methylindol, hemoglobin, BSA

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Final - PDMS Wells & Proteins

• Filled wells with needle and added additional layer of PDMS to cover needle holes• Consistently prevented leaking• Did not affect mixing

• Bubbles still created during mixing• Could be improved by loading in vacuum

• Size of device adjusted to fit overall device design

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Spectroscopy Design

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Preliminary - Bioassay Design

● Ability to study proteins in a 1U satellite lead to the selection of an assay based on fluorescence spectroscopy○ UV-LED ⇒ Intrinsically Fluorescent Proteins ⇒ Photodiode○ Signal too noisy

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● Filter at 357 nm added to avoid flooding photodiode

Intermediate - Filter + Different Molecules

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● Testing on additional molecules● 3-methylindole selected

○ Tryptophan imitator (primary source of fluorescence in protein)

Final - Photodiode Improvement

● No detectable signal, a better photodiode was pursued● Outcome: Measurable difference in folded proteins versus unfolded

○ 8M urea utilized to cause unfolding○ Fluorescence reading higher in denatured conformation

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Mechanical Design

Preliminary - Chassis

http://www.clyde-space.com/cubesat_shop/structures/1u_structures/115_1u-chassis-walls

• 1U Skeletonized Chassis by Pumpkin Inc.

• 5052-H32 Aluminum • Walls - 1.27mm thick • Bases - 1.5mm thick • Rated for -40 to +85 °C • 97.46mm X 97mm interior

• Meets required NASA standards for CubeSats as well as different launchers Walls

Bottom Base

Lid

Rails

Intermediate – Chassis: CAD Files

Chassis

Walls

Bases

Feasibility Prints and Model● Makerbot Replicator 2X● Helps customers visualize scale of a CubeSat

Solenoid Mounts and Spectroscopy Stack

-3D printed device to support both small push solenoids. -Keeps PDMS device in place-Aligns LED, microfluidic well, filter, and photodiode.

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Final - Waterjet ● Chassis cut utilizing the waterjet

- 6061, 2mm Aluminum● Metal tabs bent on press brake● Bolted together

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Thermal Analysis ● 4 heat sources

○ Direct Solar radiation ○ Albedo (Radiation from sun

bounces off earth) ○ Earth Infrared ○ Internal heat generatio

● CubeSat temperature needs to be modeled so that the future design can keep the temperature of the protein stable.

Direct Solar

Albedo Infrared

http://cdn.phys.org/newman/gfx/news/hires/2013/3-johnshopkins.jpg

Radiation● Model created focusing solely on radiation ● 5052-H32 Aluminum material properties used ● Heat Flux of 1W/m^2 ● Initial temperature of cubesat of 22°C

1s: 21.9°C - 22°C 11hrs: -28.846 - -28.72 1hr: 15.327 - 15.57°C 8hrs: -1.22°C - -1.03°C

Radiation

● Computer not able to run simulations past 11 hours.

● Minimum temperature as a function of time appears very linear.

● According to literature temperature should stabilize at about -40°C

○ Using best fit line this should occur around 13 hours

Vibrations - Modal Analysis ● Results

○ Mode 1: 56.271Hz ○ Mode 2: 152.1Hz○ Mode 3: 156.3Hz ○ Mode 4: 157.75Hz ○ Mode 5: 171.79Hz

● Mode 1 is significantly lower than 100 Hz. Changes to internal components should not result in drastic changes.

Electrical Design

Preliminary - HW Design

• Primary constraint payload size• Rapid prototyping also required• Various sensors and control

• Temperature• Current• Solenoids• LED/Photodetector

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Intermediate - Prototyping

• Components chosen for fast dev time• Teensy 2.0• Sensor breakout boards

• Arduino software reduced testing time• Matlab analysis determined component selection

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Final - PCB board w/ components

• Custom PCB designed using standard CubeSat layout• Separate LED board for experiment• Programmed with Arduino software

• Full solenoid/LED control• Can read and transmit system data

• temperature• current consumption

• Can read and transmit experiment data• photodetector• LED state

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Completed Design

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Risk Analysis

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Problem Tracker

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Final Customer Requirements

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Final Engineering Requirements

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Next Steps

● Improve microfluidic channel○ Mixing○ Storage for more proteins

● Design system to survive space flight ○ Radiation hardened electronics ○ Thermal protection ○ Vibration testing ○ Space ready chassis

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