ELECTROANALYTICAL AND SURFACE CHARACTERIZATION OF ENCAPSULATED IMPLANTABLE MEMBRANE PLANAR MICROSENSORS

The selective polymeric membranes of planar microsensors sensitive to inorganic analytes of biomedical interest (e.g., H+, K+), fabricated o n a flexible polyimide (Kapton(R) DuPont) substrate using a combinatio n of thin-film, thick-film and packaging technologies, were encapsulat ed with a biocompatible polymeric material such as poly(2-hydroxyethyl methacrylate) (poly-HEMA), The electroanalytical characteristics pf th ese sensors (linear activity ranges, slopes of the calibration curves, response times, membrane resistances, and selectivities) are not sign ificantly different when compared with those of non-coated membrane se nsors. The encapsulated membrane electrodes show improved analytical c haracteristics after exposure to whole blood samples for specified per iods of time. The long-term stability of the membranes for in vivo use was investigated by the cage implant system; the membrane biostabilit y and cell adhesion, at 1, 3, 7, and 14 days of subcutaneous implantat ion in Sprague-Dawley rats, were evaluated by scanning electron micros copy.