A modular micromachined high-density connector for implantable biomedical systems

This paper presents a high-density, modular, low-profile, small, removable connector system developed using micromachining technologies for biomedical implants. This system consists of a silicon probe with one end in contact with the biological tissue and its back end attached to a titanium base that is fixed on the test subject. An external glass substrate, which supports a flexible polyimide diaphragm and low-noise CMOS buffers (~160 nV/√Hz), is attached to the titanium base whenever electrical recording/stimulation is to be carried out. The polyimide flexible diaphragm contains high density gold electroplated pads which match similar pads on the silicon back end. When vacuum is drawn between the silicon substrate and the polyimide diaphragm, the polyimide diaphragm deflects and the gold pads on silicon and polyimide touch, therefore establishing an electrical connection. In-vitro electrical tests have been performed on a 32-site connector system demonstrating <20 Ω contact resistance and -60 dB cross talk between adjacent channels