Closed EWOD-based low-cost portable thermal detection system for point-of-care applications

Abstract

Electrowetting-on-Dielectric (EWOD) is a powerful technology for biological and chemical diagnostics. It offers advantages of low sample volume, high sensitivity, high throughput and the possibility of automation. Of special interest is a miniaturization of a thermal detection system by utilizing the EWOD technique since it can minimize effort while reducing cost and the system size. The present study describes the development of a closed EWOD device for droplet actuation that is integrated with thermal cycling and optical diagnostics. Important steps, including sample and reagent transportation, merging and mixing, and color detection, are performed on the integrated platform. The thermal module uses heating as well as Peltier elements and K-type thermocouples with a PID controller to perform precise thermal cycling needed in clinical and medical diagnostics. Experimentally recorded temperature distribution that is realized in the closed EWOD configuration is numerically validated using the COMSOL simulator. The efficacy of the integrated system is experimentally demonstrated by performing Fehling’s test for glucose detection in a glycerin solution. Furthermore, the device is used to demonstrate the transportation of a liquid drop of blood mimicking liquid at a relatively high temperature of 90 °C. The system thus developed is reliable, providing real-time proof-of-concept and the feasibility of building a low-cost point-of-care EWOD device. • A portable closed EWOD based medical diagnostic system with thermal cycling is demonstrated. • Thermal management using heating and cooling element is integrated with the closed EWOD device. • Temperature distribution within the device is measured experimentally and validated against simulation. • Droplet motion is successfully realized over the temperature range studied, providing real-time proof-of-concept. • The system developed is tested by performing Fehling’s test for glucose detection.