Microwave Microfluidic Glucose Sensor Based on a Single-Port Dumbbell Defective Ground Structure

A microwave microfluidic nonenzymatic glucose sensor is proposed for measuring the concentration of glucose in aqueous solution, which is realized by combining a single-port dumbbell defective ground structure (DB-DGS) resonator with a microfluidic channel at the center bar area of the dumbbell. The microfluidic channel, which is made of PDMS, is used to deliver the glucose solution to the dumbbell bar-sensitive area of the sensor. The glucose concentration can be measured by recording the change in amplitude of the return loss S11 at the resonance frequency. The DB-DGS sensor possesses high sensitivity owing to the high-intensity electric field generated at the dumbbell bar area when it reaches resonance. The sensor demonstrated a fast response time of 16.2 s, good accuracy (the measured glucose values deviate from the actual glucose values by less than 20%), long-term stability (the relative standard deviation for 30 days is 3%), and repeatability (the relative standard deviation for different sensors is 2.3%).