A Wireless, Passive Chemo-Mechanical Glucose Sensor

A wireless, passive chemo-mechanical sensor was developed for glucose monitoring. The sensor consisted of an airtight chamber split into two compartments by a glucose-permeable membrane. The lower compartment was a flow chamber for the test liquid to pass through, and the upper compartment was a circular drum with the glucose-permeable membrane at the bottom and a soft silicone rubber membrane on top. A permanent magnetic strip (biasing element) and a magnetically soft strip (sensing element) were attached to the soft rubber membrane and a polycarbonate block suspended over the rubber membrane, respectively. A magnetic AC field and a DC field were applied to the sensing element to generate higher order harmonic fields that were remotely measured with a detection coil. To measure glucose concentration, the permeable membrane was coated with glucose oxidase (GOD) enzyme. When glucose flowed through the lower chamber, it seeped through the membrane to the the upper compartment and interacted with the GOD enzyme and consumed oxygen. This caused a pressure drop in upper compartment that pulled the soft rubber membrane inward, changing the separation distance between the two magnetic elements and shifting the higher order harmonic fields. The advantages of this sensor platform include its simplistic design, low cost, as well as its wireless and passive nature. Although this technology was only applied for glucose monitoring, it could be used for other chemicals with the proper enzyme or catalyst coating on the permeable membrane.