An Interstitial Fluid Transdermal Extraction Chip with Vacuum Generator and Volume Sensor for Continuous Glucose Monitoring

Abstract

A five layer microfluidic chip which is designed and fabricated for interstitial fluid (ISF) transdermal extraction, collection, and measurement toward the application of continuous and real-time glucose monitoring is presented in this paper. The microfluidic chip consists of a Venturi tube generating vacuum for ISF extraction and fluid manipulation, a novel volume sensor of electrolytic fluid for normal saline input volume control and ISF volume measurement, pneumatic valves for fluid management, and access ports for glucose sensor integration. The output vacuum of the Venturi tube is tested, and a less than 88kPa vacuum has been achieved, when 220kPa external pressure is applied. The feasibility of using the volume sensor to control and measure the normal saline input volume is confirmed by high accuracy and low coefficient of variation (CV=0.0040, n=12). The microfluidic chip is ready for glucose sensor integration in continuous glucose monitoring.