Lactate Sensor Design: Smart Gels for Diabetes Pre-screening Toby Li, Wern Ong, Joseph Sun, Stephanie Wu & Christine Zhang Advisors: Franz Baudenbacher, Ph.D. & Paul King, Ph.D Introduction Use of more sophisticated fabrication techniques including the use of sonication in order to produce more sensitive polymer and more accurate readouts Introduction of a colorimetric assay as a means of internal control Incorporate digital readout for easy to read and accurate readouts Establishing testing protocols for use of this device in public health settings 1.Traitel, Tamar. "Characterization of Glucose-sensitive Insulin Release Systems in Simulated in Vivo Conditions." Biomaterials (2000): Print. 2.Segura, R. "A New Approach to the Assessment of Anaerobic Metabolism: Measurement of Lactate in Saliva." Journal of Sports Medicine (1996): Print. 3.Crawford, Stephen O. "Association of Blood Lactate with Type 2 Diabetes: the Ahterosclerosis Risk in Communities Carotid MRI Study." International Journal of Epidemiology (2010): Print. 4.American Diabetes Association. "Economic Costs of Diabetes in the U.S. in 2007." Diabetes Care (2008): Print. Purpose Design and develop a diabetes pre-screening device to fill market void Background Cost of diabetes (direct/indirect) per person = $11,744 per year Cost of diabetes over lifetime (33 yrs) = $387,552 per person 4 Cheap, non-invasive, accurate, and easy to use device is needed for large scale pre- screening and diabetes prevention Solution Develop hydrogel based lactate sensor that is sensitive to saliva lactate levels Volumetric change (swelling) of hydrogel polymer caused by saliva lactate concentration is correlated to blood lactate levels Correlation of lactate concentration to development of type-II diabetes If test is positive, patients can take steps to prevent development of the disease including changes to diet and exercise Diabetes: Chronic illness Characterized by high blood sugar Caused by insufficient insulin levels Body has become resistant to insulin Medical expenditure of diabetics is 2.3x higher than non-diabetics Figure 1. Prevalence of diabetes in the population. Risk Factors: Age Ethnicity Weight Family History Other Symptoms Complications: Heart Disease/Stroke High Blood Pressure Blindness Kidney Disease Nervous System Disease Amputation Design 1Design 2 Figure 4. Different design approaches. Design 1 utilizes the direct volumetric change caused by swelling. The volumetric change caused by directional swelling is extremely small and difficult to measure. Design 2 amplifies the change in volume for more accurate and sensitive readouts. Figure 10. Shows the inputs and outputs of the hydrogel lactate sensor system. Figure 5. Shows the response of different hydrogel configurations to an acidic solution. Figure 6. Hydrogels of different lactate oxidase configurations and their response to different solutions using Design 1. Figure 2. Shows the correlation of saliva lactate levels to lactate levels in the blood 3. Figure 3. Correlates lactate levels in the blood to the probability of developing type-II diabetes 2. Mix hydrogel ingredients together using proper volumetric ratios Dry overnight in oven and then soak hydrogel polymer in deionized water Measure un-stimulated wet weight Soak hydrogel with lactate solution Measure stimulated wet weight and calculate Q ratio (stimulated/un-stimulated) A1C Test Glycated Hemoglobin $20-$30Needle Prick6 weeksLab/Home SettingVaried Results Fasting Plasma Glucose Test Plasma GlucoseLow CostDraw Blood12-14 hrs FastingLab Setting May not identify pre-diabetes Oral Glucose Tolerance Test Blood GlucoseExpensive Complaints Nausea Fasting + 4 hrsLab SettingAccurate Results Smart Gel Lactate Sensor Saliva LactateLow Cost: $0.29Non-invasive2.5 hrsSelf TestingVaried Results Hygienic, fast-acting, non-invasive, disposable, uniform, and cheap lactate sensor Measurement of volumetric change by Q ratio shows reaction of hydrogel polymer to various lactate concentrations Hydrogel polymer sensitive to lactate concentrations in the mmol range Proof of concept for future lactate sensor design Diabetes Background Methods Conclusion Future Considerations References Methods Results PolymerCost ($) HEMA0.33 DMAEMA1.80 TEGDMA0.10 EG0.42 Water0.00 Ammonium Persulfate0.02 Sodium Bisulfite0.01 Total2.67 Number Tubes74 Gel Costs$2.67 LOD costs$17.48 Total Costs$21.11 Cost per Tube$0.29 Figure 9. Financial analysis of the cost of production including material costs. Figure 7 & 8. Measurement of volumetric change by beans of Q ratio after 2.5 and 24 hours of exposure show the hydrogel polymer’s reactivity and sensitivity to different lactate concentrations.