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Microbial Detection Arrays

Microbial Detection Arrays. MiDAs. Jeff Childers Dave Miller Elizabeth Newton Ted Schumacher. Shayla Stewart Steven To Charles Vaughan Sameera Wijesinghe. Critical Design Review December 5th, 2006 Aerospace Senior Projects University of Colorado – Boulder

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Microbial Detection Arrays

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  1. Microbial Detection Arrays MiDAs Jeff Childers Dave Miller Elizabeth Newton Ted Schumacher Shayla Stewart Steven To Charles Vaughan Sameera Wijesinghe Critical Design Review December 5th, 2006 Aerospace Senior Projects University of Colorado – Boulder Advisors: Dr. Forbes and Dr. Maslanik Customers: BioServe and Tufts University

  2. Briefing Overview • Overview of Objectives and Requirements • System Architecture • Prototype Results • Mechanical Design Elements • Electrical Design Elements • Software Design Elements • Integration, Verification, and Test Plan • Project Management Plan • Appendices

  3. Objectives • Component of larger project • Future Mars astrobiology mission from BioServe/Tufts University/JSC • Astrobiology objective: electrochemical sensing of metabolic activity • Three components: biology (JSC), sensors (Tufts), instrument hardware (CU) • MiDAs team objective: instrument hardware component • Design/build integrated field instrument with meaningful biological and spaceflight constraints • Validate key functions to enable field research • Extends proof-of-concept from lab to field • Raise TRL from 1-3 to 4-5

  4. TRL Objective https://www.spacecomm.nasa.gov/spacecomm/programs/technology/default.cfm

  5. Deliverables • Field-ready unit (TRL 4-5) • Test data that verifies requirements • Operational manual for use • Document proposing design solutions to further raise the TRL (to 6-7)

  6. Requirements Overview • Samples placed in autoclaves • Autoclaves heated to 121°C and held for 15 minutes • Autoclaves cooled to 20°C and held for 24 hours • Process may be repeated up to 3 times • Valves opened • Water pumped into autoclaves • Sample flushed into reaction chambers • Inoculation sample added to test chamber • Environmental chamber maintained between 4°C and 37°C • Mixers stir sample and water • Sample is tested for 14 days Water tubing not shown

  7. Requirement Refinement • Complete autonomy no longer primary goal • Increased reliance on experimenter to open valves and deliver inoculation sample • Instrument will not provide its own power • Reason: • Change at request of customer – trades autonomy for reliability in field instrument • Autonomy adds expense, complexity, and failure modes without proving key concepts or raising TRL • Autonomy options will be included in design document • Key components maintained in field instrument

  8. Mars/Earth Comparison

  9. System Architecture (External) Dimensions: 18” x 18” x 15” (46 cm x 46 cm x 39 cm)

  10. System Architecture (Internal) 15” (39 cm) 10” (25 cm) 16” (40 cm)

  11. Mass Analysis 2 Pumps 127g Insulation 9.83g Water Chamber 132g 2 Autoclaves 1890g 2 Valves 1450g Tubing 396g 4 TECs 720g Environmental Chamber 656g 2 Reaction Chambers 173g Chassis 1150g 2 Mixers 95.8g CPU and DAq (not shown) 292g Internal Mass: 7.10kg (15 lbs) Total Mass: 13.90 kg (30 lbs) Sensors (not shown) 10.0g

  12. 2 weeks + 27 to 75 hr 27 hr 75 hr 51 hr 3 hr 1.5 hr 73.5 hr 49.5 hr 25.5 hr t5 t1 t4 t2 t3 t6,7,8,9 -- -- -- S F* -- ** F* S -- **optional Can repeat two more times t6 ___A B___ Heater A: Heater B: Cooler A: Cooler B: Reaction Experiment Timeline Finish Start 0 30 s Soil Soil ___A B___ Heater A: Heater B: Cooler A: Cooler B: Cycle A: Cycle B: Autoclave t= 0 Insert sample manually A B Soil Soil

  13. Electrical Overview KEY

  14. Autoclave Prototype • Concerns: • Low power heating • Seals • 304 Stainless Steel • Height = 2.25 in. • Inner Diameter = 1.5 in • LabView • External temperature sensor • Internal pressure sensor

  15. Prototype Thermal Analysis • Steady state 2W energy loss • Heater on flat area • Large thermal gradient

  16. Autoclave Prototype Results • Results: • 121 C for small 12W strip heater, higher pressure than expected • Very uneven heating • Seals held • Conclusions: • 3 smaller strip heaters evenly spaced • TEC used only for cooling • O-ring seals were effective • Melamine insulation was effective

  17. Mixing Prototype • Ultrasonic • Frequency function of tip length • 18 kHz not feasible • Magnetic • May disrupt electrochemical sensors • Pending tests by Tufts • Mechanical • No off-the-shelf impeller options • Custom impeller designed

  18. Mixing Prototype Results Results: • Too much slip with impeller to use motor • Had to rotate impeller manually • Sample developed air bubbles • Flour-like consistency  very slow settling time • Sediment remains on bottom of chamber Conclusions: • Fluid movement around sides easily maintained • Need cross-bar near the bottom • Can maintain colloidal solution for several minutes without continuous mixing with 10-micron grains

  19. Sample Transport Prototype Results Results: • ¾” tubing did not transport sample • 30% soil transported when dry • 95% soil transported when wet • Autoclaving did not affect soil consistency Conclusions: • 1” tubing • Water added to move sample

  20. Lid Sensor Ports O-ring Body 1” diameter Autoclave Drawings • 316 stainless steel • Height = 2 in. with flat sides = 1.6 in. x 1.6 in. • Wall thickness = 0.125 in. • Inner Diameter = 1.5 in. tapered Bottom View Valve Interface

  21. Ultem 1000 Height = 5.2 in. (13.19 cm) Diameter = 1.6 in. (3.95 cm) Wall thickness = 0.197 in. (0.5 cm) Soil transport pathway = 1.0 in. (2.5 cm) Cap to support mixing shaft 20 sensor ports 12 electrochemical sensors 7 multi use ports 1 temperature sensor Reaction Chamber Drawing Cap Sensor ports Impeller Motor Reaction Chamber with Mixer and Cap

  22. Autoclave Stress Analysis • Autoclave technique: • 121 C with steam to aid heat flow • 15 psi above atmosphere for saturated steam at 121 C • Thin wall pressure formulas: • Minimum thickness = 0.011 in. while actual used = 0.125 in. • Critical pressure for 0.125 in. is 20 kpsi • Seals: • Regular threads alone will not seal • O-ring compression seals made of silicone for high temperature and pressure • Conclusions: • O-ring seals are effective • Temperature of chamber is regulated and heater has limited heating power • Pressure relief valve added to 10-32 port on lid

  23. Electrical System • Power supply is 12V • Power conditioning is added to give cleaner power • 5V power will be used to run sensors because of voltage stability AC-DC converter Voltage regulator Power supply

  24. Sensors and Control • Sensors will run constantly • Switchboard controls power to: • TECs, mixers and LEDs • The DAQ card can proportionally control: • Pumps, TECs and mixers

  25. Finish Start 0 2 weeks + 27 to 75 hr 27 hr 1.5 hr 30 s Turn on Done Turn Valve Heating complete Pumping complete Done Autoclave A Autoclave B Water pump A & B Reaction Chamber Insert sample Software Timeline • Autoclave control • User turns on program • Autoclave A begins heating • At 121˚C Autoclave A holds for 15 min • Autoclave A begins cooling and Autoclave B begins heating • Autoclave A finishes cooling • Autoclave B finishes cooling • Program notifies user autoclave has completed • Reaction control • User turns valves open and beings program • Turn on pumps for 25 sec (at 1mL/sec flow rate) • Turn on Reaction Chamber control

  26. Make Buy Assembly Flow Diagram

  27. Functional Test Plan TEC Heat from -10°C to 121°C Hold for 15 min Cool to 20°C Repeat 3 times Thermal Control Strip Heater Autoclave Butterfly Valve Transport 90% of sample when reagent water pumped through Sample Transport Sample Consistency TEC Maintain temperature between 4°C and 37°C Thermal Control Reaction Chamber Motor Maintain fluid movement around sides; Maintain minimal sedimentation on sides and bottom of chamber Mixing Impeller Collection & Storage Interface Collect & store data from each sensor Receive commands from SW Provide caution, warning, status signals DAQ & Control Software Command

  28. Verification and Test Plan Temperature 4°C – 37°C Thermistor in environmental chamber Reaction Chambers Pressure 1 psi differential Pressure sensor in environmental chamber Mixing Small sedimentation, fluid flow @ sensors Visual/Video verification Temperature ≥121°C Thermistor inside autoclave chamber through cap Autoclaves Pressure ≥15 psi Pressure sensor inside autoclave chamber through cap Sample sterility No microbial life in sample Petri dish testing with bacteria and medium (BioServe) Containment Solid & liquid form Thermistor inside autoclave chamber through cap Reagent H2O Chamber ≤50mL (±5% accuracy) Time-based flow rate in peristaltic pump (controlled flow) Delivery < 60°C Thermistor inside water chamber Sample Transport Sterilized sample Aseptic delivery Sterile swabbing of wet surfaces, culture test Inoculation Collection & Storage Collected & stored for entire experiment DAQ storage capability analysis Data Acquisition & Control Caution, Warning, Status Provide status, caution & warning signals Testing LabView command software with set max temperature and shut-off abilities Nominal Consumption ≤ 30W Power Power model for all parts, measurement through multimeter in circuit Peak Consumption ≤ 30W for ≤ 30 sec

  29. High Severity Medium Low Low Medium High Probability Risk Assessment

  30. Work Breakdown Structure

  31. Schedule

  32. Overall Budget

  33. Resources and Facilities • BioServe Laboratories • Matching funds • Spare/small parts • Machine shop • Temperature-controlled testing environment • Wet/Biological lab • Clean room • Aerospace Department • Machine Shop • Electronics Shop

  34. Conclusions • Project feasible • Team has necessary expertise, time and resources • Risk mitigated through prototyping • Can increase overall TRL

  35. References • Cengel, Yunus. Introduction to Thermodynamics and Heat Transfer. • McGraw-Hill.University of Nevada, Reno. 1997 • Gilmore, David. Spacecraft Thermal Control Handbook. Aerospace press. El Segundo, California. 2002 • Mankins, John C. “Technology Readiness Levels.” April 6, 1995. http://ipao.larc.nasa.gov/Toolkit/TRL.pdf. • www.dimondsystems.com • www.kontron.com • www.matweb.com • www.mcmaster.com • www.melcor.com • www.minco.com • www.omega.com • www.sonaer.com

  36. Presentation Appendix • Title Page • Briefing Overview • Objectives • TRL Objective • Deliverables • Requirements Overview • Requirement Refinement • Mars/Earth Comparison • System Architecture (External) • System Architecture (Internal) • Mass Analysis • Experiment Timeline • Electrical Overview • Autoclave Prototype • Prototype Thermal Analysis • Autoclave Prototype Results • Mixing Prototype • Mixing Prototype Results 19. Sample Transport Prototype Results 20. Autoclave Drawings 21. Reaction Chamber Drawings 22. Autoclave Stress Analysis 23. Electrical System 24. Sensors and Control 25. Software Timeline 26. Assembly Flow Diagram 27. Functional Test Plan 28. Verification and Test Plan 29. Risk Assessment 30. Work Breakdown Structure 31. Schedule 32. Overall Budget 33. Resources and Facilities 34. Conclusions 35. References

  37. Drawing Tree

  38. Drawing Tree (continued)

  39. Mechanical Drawing Tree

  40. Autoclave Body

  41. Autoclave Cap

  42. Autoclave Bottom

  43. Thermoelectric Cooler (TEC)

  44. Heat Sink

  45. Reaction Chamber

  46. Reaction Chamber Cap

  47. DC Motor

  48. Impeller

  49. Reaction Chamber Environment

  50. Reaction Chamber EnvironmentSide Door

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