Calvin College Engineering Senior Design Team 10 March 28, 2008

Outline Introduction Design MFC Power Regulation System Monitoring Feed/Waste System Budget Moving Forward

Jared Huffman Brianna Bultema Achyut Shrestha Chris Michaels Team 10: Members

Project Division Four Main Parts of Our Biobattery Project Microbial Fuel Cell Electrical Monitoring Electrical Regulation Feeding and Case Design IntroductionDesignBudgetMoving Forward

How Microbial Fuel Cells (MFC) Work Schematic courtesy of Derek R. Lovely (Microbial Energizers: Fuel Cells the Keep Going?) IntroductionDesignBudgetMoving 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 Design Species: Geobacter Metallireducens Most Efficient Colonization and Power Density Widely tested Membrane: Cellophane vs Nafion Balance Cost and Permeability Electrode: Carbon Cloth vs Carbon Porous Block IntroductionDesignBudgetMoving Forward

Design Goals USB Power output 5V, 5% tolerance A Refillable Food Supply with Alert Semi-Continuous System Monitoring User friendly Indicates Failure Mode Improved Power/Volume Ratio Anode Cube IntroductionDesignBudgetMoving Forward

Anode Cube Food Input Waste Output Electrode Location (Each Face) MFC DesignRegulationMonitoringFood/WasteBudget

Design Fuel cell arrangement and composition Will use a combination of serial and parallel circuit design Lower chance of battery and circuit failure IntroductionDesignBudgetMoving Forward

Design Regulation Must output 4.75V-5.25V and 100mA-500mA for USB compatibility Must overcome low current problem Must step up voltage from about 3.3V to 5V Will use the Maxim MAX1524 Boost Controller IntroductionDesignBudgetMoving Forward

IntroductionDesignBudgetMoving Forward Regulator Circuit Fig. Regulator circuit

Parallel vs. Series Configuration MFCMFC Regulator Monitor Fault signal MFCMFC Regulator Monitor Fault signal Fig. Parallel configuration Fig. Series configuration IntroductionDesignBudgetMoving Forward

Parallel configuration Parallel configuration of regulator and monitor circuits Preserve system integrity IntroductionDesignBudgetMoving Forward

MFC Monitor Design Goal Monitor the status of the system and communicate relevant status to user Requirements 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 system User friendly Components RoHS compliant and lead free IntroductionDesignBudgetMoving Forward

MFC Monitor Design micro-controller ADC LCD Voltage output from MFC Feed/waste removal signal Fault signal IntroductionDesignBudgetMoving Forward Fig. Block diagram

Monitor Design Initial State Vin MFC Waste Interrupt Output interrupt goodbad alertwarning Fig. State Machine IntroductionDesignBudgetMoving Forward

MFC Monitor Design AVR butterfly kit Atmega169 micro- controller 10 bit ADC & LCD Low power consumption: < 500µA RoHS compliant No speciality hardware/software need for programming IntroductionDesignBudgetMoving Forward Fig. Block diagram

Feeding and Waste System Food Solution Bladder Tubes and Valves Thumbscrew Valves to Control Rate One Way Valves to Prevent Backflow Cubes Fed in Sets of 2, Bottom to Top Waste Tank IntroductionDesignBudgetMoving Forward

Feeding and Waste System Food Solution Bladder Filled by User Periodically Cathode Tank Waste Tank Emptied by User Periodically Anode Cube IntroductionDesignBudgetMoving Forward

Decision-Making Process 1. Brainstorm (Group and Individual) 2. Discuss Design Requirements 3. Research 4. Design 5. Present Design to Team 6. Refine Design 7. Present Refined Design to Team 8. Order Parts 9. Assembly 10. Testing IntroductionDesignBudgetMoving Forward

Budget Preliminary Budget estimation = $750 Spent Geobacter & media Testing components such as tubes, AVR butterfly kit $350 IntroductionDesignBudgetMoving Forward

Budget Planned Electrodes and membrane Feeding and waste system Electrical components $400 IntroductionDesignBudgetMoving Forward

Budget Donation Test equipments from chemistry and biology departments Plexiglas, carbon cloth and membrane IntroductionDesignBudgetMoving Forward

Obstacles and Plans Case design Need to find a tank for the cathode Need to select and acquire a feed bladder Must find a waste tank Must select an appropriate feed rate IntroductionDesignBudgetMoving Forward

Obstacles and Plans Bacteria 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 IntroductionDesignBudgetMoving Forward

Obstacles and Plans Electrical regulation Need to order parts Need SchmartBoard to solder surface mount parts Need to test circuit in lab Electrical monitoring Need to interface the different components with the monitoring system Complete system test IntroductionDesignBudgetMoving Forward

Questions?