1. Microfluidic Glucose Sensor Senior Design Group 4 Kristen Jevsevar Jason McGill Sean Mercado Rebecca Tarrant

2. Problem Statement Primary Objective Primary Objective To quantify glucose or other metabolite consumption/production on a scale of microliters To quantify glucose or other metabolite consumption/production on a scale of microliters Design a glucose electrode interface that will measure micro-scale concentrations while maintaining affordability Design a glucose electrode interface that will measure micro-scale concentrations while maintaining affordability To date, there are very few ways to measure these metabolites easily and inexpensively. Using a readily produced electrode, it is possible to measure glucose levels on a small scale, easily.

3. Applications Biological researchers may use this to study properties of cells, such as metabolism Biological researchers may use this to study properties of cells, such as metabolism Currently, researchers measure cellular metabolites, such as glucose, on the scale of milliliters. Smaller volumes yield more accurate results Smaller volumes yield more accurate results PDMS and ceramic electrodes are inexpensive PDMS and ceramic electrodes are inexpensive

4. Similar Systems Specially designed electrodes already exist that are able to measure glucose concentrations They are expensive to make and often measure more accurately than necessary for some experiments This design utilizes a commercially produced electrode that is much larger This design utilizes a commercially produced electrode that is much larger This electrode is interfaced with a microfluidic pumping device that allows small volumes to be studied This electrode is interfaced with a microfluidic pumping device that allows small volumes to be studied

5. Performance Criteria Must be able to measure glucose concentrations between 0mM and 6mM Must be able to measure glucose concentrations between 0mM and 6mM Must be affordable Must be affordable Needs to work for at least 24 hours Needs to work for at least 24 hours Should recalibrate automatically to account for electrochemical drift Should recalibrate automatically to account for electrochemical drift

6. Design Components Electrode Electrode Channel System Channel System Electrode Clamp Electrode Clamp Pumping System Pumping System Bioreactor Bioreactor

7. Experimental Design: the Electrode Cellular glucose sensors consist of an electrode that utilizes a chemical reaction to determine glucose concentrations Cellular glucose sensors consist of an electrode that utilizes a chemical reaction to determine glucose concentrations The electrode consists of three “prongs” The electrode consists of three “prongs” Working electrode Working electrode Reference electrode Reference electrode Counter electrode Counter electrode

8. Experimental Design: Channel System Using a CNC, a PDMS mold was made to create uniform channels Using a CNC, a PDMS mold was made to create uniform channels Solution containing glucose is run through these channels, passing over the electrode Solution containing glucose is run through these channels, passing over the electrode Channel Electrode Shape

9. Experimental Design: Electrode Clamp Several fiber glass slabs are placed on each side of the electrode to clamp the PDMS in place, sealing the system from leakage Several fiber glass slabs are placed on each side of the electrode to clamp the PDMS in place, sealing the system from leakage Clamping pressure can be manually adjusted Clamping pressure can be manually adjusted

10. Experimental Design: the Pumping System Tubes are then run through holes drilled in the fiber class slabs Tubes are then run through holes drilled in the fiber class slabs These tubes are then attached to the Harvard Apparatus pumping system These tubes are then attached to the Harvard Apparatus pumping system

11. Experimental Design: Bioreactor The bioreactor cultures and feeds a small amount of cells into the electrode housing The bioreactor cultures and feeds a small amount of cells into the electrode housing The Harvard Apparatus pumps media and glucose, in respective tubes, from the bioreactor to the electrode housing The Harvard Apparatus pumps media and glucose, in respective tubes, from the bioreactor to the electrode housing

12. Experimental Design: Electrochemistry The glucose concentrations are measured using an electrochemistry workstation The glucose concentrations are measured using an electrochemistry workstation

13. Materials Pine Instruments platinum ceramic electrode Pine Instruments platinum ceramic electrode PDMS PDMS Fiber glass Fiber glass Clamp Clamp Tubing Tubing Harvard Apparatus Harvard Apparatus Bioreactor Bioreactor Glucose, glucose oxidase, media Glucose, glucose oxidase, media Electrochemistry workstation Electrochemistry workstation

14. Future Direction Successfully measure small scale metabolite concentrations Successfully measure small scale metabolite concentrations Lactate Lactate pH pH Oxygen Oxygen

15. Previous Experiments Calibration curve in beaker

16. Previous Experiments Calibration curve in microfluidic device Linear Trend

17. Questions?