Calvin CollegeEngineering Senior Design

Team 10April 24, 2008

OutlineIntroductionMicrobial Fuel CellsRegulationMonitoringFeeding / Case

Jared Huffman

Brianna BultemaAchyut Schrestha

Chris Michaels

Team 10: Members

Why Biobattery?

Problems of Conventional Batteries

“Hard to Do”

Interdisciplinary Talents

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Design GoalsUSB Power output

5V, 5% tolerance0.1-0.5A

Refillable Food Supply with AlertSemi-Continuous

System MonitoringUser friendlyIndicates Failure Mode

Improved Power/Volume RatioAnode Cube

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Decision-Making Process1. Brainstorm (Group and Individual)2. Discuss Design Requirements3. Research4. Design5. Present Design to Team6. Refine Design7. Present Refined Design to Team8. Order Parts9. Assembly10. Testing

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Project DivisionFour Main Parts of

Our Biobattery ProjectMicrobial Fuel CellsMonitoringRegulationFeeding and Waste

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

How Microbial Fuel Cells (MFC) Work

Schematic courtesy of Derek R. Lovely Schematic courtesy of Derek R. Lovely (Microbial Energizers: Fuel Cells the Keep Going?)(Microbial Energizers: Fuel Cells the Keep Going?)

Story of Electrons:Anode•Electrons from Acetate to Geobacter•Geobacter sends electrons outside itself to electrode

Cathode•Electrons combine with Oxygen and Protons to form water

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Microbial Fuel Cells

Bacteria: Geobacter MetallireducensElectrode Material: Carbon ClothMembrane Material: Nafion vs CellophaneMembrane Electrode Assembly: SandwichFacultative Aerobic Bacteria

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Regulation

Output: 4.75V-5.25V, 100mA-500mA for USB Compatibility

Must step up voltage from 3.0V to 5.0V

Will use the Maxim MAX1524 Boost Controller

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Regulation

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Parallel vs. Series Configuration

MFC

Regulator

Monitor

Fault signalMFC

Regulator

Monitor

Fault signal

Parallel Configuration Series Configuration

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

GoalMonitor the status of the system and

communicate relevant status to userRequirements

Update user the system status feed and waste removal voltage produced by MFC circuit integrity, for e.g. over-current, short circuit

Use minimum power to monitor the systemUser friendlyComponents RoHS compliant and lead free

Monitoring System

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Initial State

Vin MFC Waste Interrupt

Output interrupt

good bad

alert warning

State Machine

Monitoring System

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Monitoring SystemAVR butterfly kit

Atmega169 micro-controller

10 bit ADC & LCDLow power

consumption: < 500µA

RoHS compliantNo speciality

hardware/software need for programming

Block diagram

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Anode Cube

Food Input

Waste Output

Electrode Location

(Each Face)

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Feeding and Waste SystemFood Solution BladderTubes and Valves

Thumbscrew Valves to Control RateCheck Valves to Prevent Backflow

Cubes Fed in Sets of 2, Bottom to TopWaste Tank

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Feeding and Waste System

Food Solution BladderReplaced by User Periodically

CathodeTank

Waste TankEmptied by User Periodically

Anode Cube

Anode Cube

Anode Cube

Anode Cube

Introduction Microbial Fuel Cells Feeding/CaseRegulation Monitoring

Conclusion

Achieved Goal of Advancing Existing Designs Toward Feasible Product

Future ProjectsFull Testing of Cellophane MembraneProduce Smaller Cube: Fabrication MethodsPlatonized Electrodes to Allow Air Cathode

Acknowledgements Professor Ray Hozalski, Civil Engineering, University of Minnesota – Twin Cities, for

samples/supplies of electrodes, membranes, and information on MEAs. Chris Harrington, Graduate Student Researcher, University of Minnesota – Twin Cities,

for help with implementation procedures. Professor Randall Brouwer, Engineering Department, for supplying VHDL code for ADC

interface. Sam Brower, Media Productions Calvin Alum, for various visual design and photographic

assistance. Bob DeKraker, Engineering Department, for logistical support with procurement of

circuit components. Rich Huisman, Chemistry Department, for assistance with salt bridge supplies. Lori Keen, Biology Department, for assistance in biological procurement and lab support. Professor Walter Rawle, Engineering Department and Senior Design Team Mentor, for

meeting with our team and assisting us with the in progress reviews. Professor Gemma Reguera, Michigan State University, for providing technical

information and expertise. Professor J. Aubrey Sykes, Engineering Department, for his ongoing role as the senior

design advisor and for all of this feedback about our project. Professor John Wertz, Biology Department, for assistance in Microbiology growth and

experimentation.

Questions?