Calvin CollegeEngineering Senior Design

Team 10March 28, 2008

OutlineIntroductionDesign

MFCPower RegulationSystem MonitoringFeed/Waste System

BudgetMoving Forward

Jared Huffman

Brianna BultemaAchyut Shrestha

Chris Michaels

Team 10: Members

Project DivisionFour Main Parts of

Our Biobattery ProjectMicrobial Fuel CellElectrical

MonitoringElectrical

RegulationFeeding and Case

Design

Introduction Design Budget Moving Forward

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?)

Introduction Design Budget Moving Forward

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

Microbial Fuel Cell DesignSpecies: Geobacter Metallireducens

Most Efficient Colonization and Power DensityWidely tested

Membrane: Cellophane vs NafionBalance Cost and Permeability

Electrode: Carbon Cloth vs Carbon Porous Block

Introduction Design Budget Moving Forward

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 Design Budget Moving Forward

Anode Cube

Food Input

Waste Output

Electrode Location

(Each Face)

MFC Design Regulation Monitoring Food/Waste Budget

DesignFuel cell arrangement and composition

Will use a combination of serial and parallel circuit design Lower chance of battery and circuit failure

Introduction Design Budget Moving Forward

DesignRegulation

Must output 4.75V-5.25V and 100mA-500mA for USB compatibility

Must overcome low current problemMust step up voltage from about 3.3V to 5VWill use the Maxim MAX1524 Boost Controller

Introduction Design Budget Moving Forward

Introduction Design Budget Moving Forward

Fig. Regulator circuit

Parallel vs. Series Configuration

MFC

Regulator

Monitor

Fault signalMFC

Regulator

Monitor

Fault signal

Fig. Parallel configuration Fig. Series configuration

Introduction Design Budget Moving Forward

Parallel configurationParallel configuration of regulator and

monitor circuitsPreserve system integrity

Introduction Design Budget Moving Forward

MFC Monitor DesignGoal

Monitor the status of the system and communicate relevant status to user

RequirementsUpdate 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

Introduction Design Budget Moving Forward

MFC Monitor Design

micro-controller

ADC

LCD

Voltage output from MFC

Feed/waste removal signal

Fault signal

Introduction Design Budget Moving Forward

Fig. Block diagram

Monitor DesignInitial State

Vin MFC Waste Interrupt

Output interrupt

good bad

alert warning

Fig. State Machine

Introduction Design Budget Moving Forward

MFC Monitor DesignAVR butterfly kit

Atmega169 micro-controller

10 bit ADC & LCDLow power

consumption: < 500µA

RoHS compliantNo speciality

hardware/software need for programming

Introduction Design Budget Moving Forward

Fig. Block diagram

Feeding and Waste SystemFood Solution BladderTubes and Valves

Thumbscrew Valves to Control RateOne Way Valves to Prevent Backflow

Cubes Fed in Sets of 2, Bottom to TopWaste Tank

Introduction Design Budget Moving Forward

Feeding and Waste System

Food Solution BladderFilled by User Periodically

CathodeTank

Waste TankEmptied by User Periodically

Anode Cube

Anode Cube

Anode Cube

Anode Cube

Introduction Design Budget Moving Forward

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 Design Budget Moving Forward

BudgetPreliminary Budget estimation = $750Spent

Geobacter & mediaTesting components such as tubes,AVR butterfly kit$350

Introduction Design Budget Moving Forward

BudgetPlanned

Electrodes and membraneFeeding and waste systemElectrical components$400

Introduction Design Budget Moving Forward

BudgetDonation

Test equipments from chemistry and biology departments

Plexiglas, carbon cloth and membrane

Introduction Design Budget Moving Forward

Obstacles and PlansCase design

Need to find a tank for the cathodeNeed to select and acquire a feed bladderMust find a waste tankMust select an appropriate feed rate

Introduction Design Budget Moving Forward

Obstacles and PlansBacteria testing

Must have a bio-film formation on the electrode

Need to select a secondary, non-competitive aerobic bacteria

Plan to allow Geobacter to colonize electrodes before applying secondary bacteria

Plan to create a large supply of media

Introduction Design Budget Moving Forward

Obstacles and PlansElectrical regulation

Need to order parts Need SchmartBoard to solder surface mount parts

Need to test circuit in labElectrical monitoring

Need to interface the different components with the monitoring system

Complete system test

Introduction Design Budget Moving Forward