Microelectrodes and biocompatible sensors for skin pO2 measurements

Abstract

The potential of monitoring oxygen (02) levels on a continuous real-time basis gives the opportunity to both assess dynamic fluctuations and make a predictive assessment of 02 trends in any particular localized environment [ii. Electrochemical and optical (fibre-optic) sensors provide a near ideal means of localized tissue monitoring other than totally non-invasive methods such as the near-infrared monitoring of the inter-converting Hb/ Hb02 chromophore pair pioneered by Jobsis [21 and referred to in Chap. 17. In both electrochemical and optical sensors, a direct interfacial reaction takes place, which can be conveniently amplified and translated into a continuous electrical output using systems suitable for near-patient use. A key capability is that of virtually reagentless measurement in an optically opaque tissue matrix ideal for subcutaneous measurement. With the advent of miniaturization techniques, including those adapted from the microelectronics industry, ethically acceptable, clinically invasive monitoring becomes feasible. Application criteria include sensitivity, selectivity, stability, biocompatibility, reliability and overall safety. Undoubtedly, an important route to overcoming many of these problems was to retain sensors behind permselective membranes and appropriate encapsulants [31. Interfacing with appropriate polymer membrane coverings has permitted the operation of many sensors independently of solution variables presented by the in vivo milieu.