Stabilised Biosensing Using Needle-Based Recess Electrodes

A recess disk electrode for amperometric monitoring of oxygen and glucose is reported. The basic design of sensor is a needle structure for easy implantation, embodying a gold filled silica capillary with a 80 mu m inner diameter working electrode. Recess and inlaid disc electrodes, placed inside stainless steel tubes which served as a counter/reference electrode, were compared. The working electrode surface was modified with different treatments and barrier membranes to achieve selectivity for the analytes of interest. The basic needle format is ideal for in vivo use, and the format is easily extendable to other analyte targets. The sensors show linear working range for oxygen up to 160 mmHg partial pressure of oxygen, and for glucose from 1 to 10 mM. Bio-fouling, as assessed by exposure to bovine serum albumin, was significantly reduced. Response times for the recess construct was increased but remained within the acceptable range for physiological monitoring. The operational stability of the sensors is demonstrated as well as the interference-free detection of peroxide in the presence of physiologically relevant levels of ascorbic acid, uric acid, acetaminophen, and catechol. Preliminary in vivo tests showed excellent response towards glucose