Lactate Sensor Design: Smart Gels for Diabetes Pre-screening

1. Lactate Sensor Design: Smart Gels for Diabetes Pre-screening Toby Li, WernOng, Joseph Sun, Stephanie Wu & Christine Zhang Advisors: Franz Baudenbacher, Ph.D. & Paul King, Ph.D Introduction Methods Methods • 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 person4 • 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 • 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) Design 1 Design 2 Figure 10. Shows the inputs and outputs of the hydrogel lactate sensor system. 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. Conclusion Diabetes • 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 0.2-0.5 mmol range • Proof of concept for future lactate sensor design Results • 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. Figure 6. Hydrogels of different lactate oxidase configurations and their response to different solutions using Design 1. Figure 5. Shows the response of different hydrogel configurations to an acidic solution. Future Considerations • 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 Background 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. References Traitel, Tamar. "Characterization of Glucose-sensitive Insulin Release Systems in Simulated in Vivo Conditions." Biomaterials (2000): 1679-687. Print. Segura, R. "A New Approach to the Assessment of Anaerobic Metabolism: Measurement of Lactate in Saliva." Journal of Sports Medicine (1996): 305-309. Print. Crawford, Stephen O. "Association of Blood Lactate with Type 2 Diabetes: the Ahterosclerosis Risk in Communities Carotid MRI Study." International Journal of Epidemiology (2010): 1647-655. Print. American Diabetes Association. "Economic Costs of Diabetes in the U.S. in 2007." Diabetes Care (2008): 596-615. Print. Figure 3. Correlates lactate levels in the blood to the probability of developing type-II diabetes2. Figure 2. Shows the correlation of saliva lactate levels to lactate levels in the blood3. Figure 9. Financial analysis of the cost of production including material costs.