Continuous Hydrogel-Based Glucose Sensors With Reduced pH Interference and Contact–Free Signal Transduction

There is a great societal need for continuous glucose sensors that can monitor glucose concentrations in patients suffering from diabetes as well as in bioreactors used to manufacture pharmaceutical proteins. In our previous paper (Nguyen et al, Sensors & Actuators B, 2018), we have shown that polyampholytic glucose-sensitive hydrogels (GSHs) that contain both fixed positive and negative charges along the polymer backbone are particularly suitable for this application, provided that the hydrogels contain an excess of positive over negative charges at typical pH values. Here, we show how the autonomous swelling response of such a polyampholytic GSH can be transduced into electrical signals using a contact-free method that employs magnetometers. Contact-free signal transduction should improve the biocompatibility of continuous glucose sensors as well as reduce the risk of corrosion to key electronic components. In addition, we show that one can substantially reduce pH interference upon the glucose sensor signal by replacing a portion of the tertiary amines present in the polyampholytic GSHs with cationic quaternary amines.