Micromachined biosensor terminals for the study of growing neurons

Abstract

Since 1972, micromachined plastic and silicon sensors have been developed at Cardiff. In planar mode, they have been used as cultivation surfaces for human neural blastoma cells and Chinese Hamster ovarian cancer cells, and recording platforms for isolated frog heart (54 channels with terminals down to 4 μm diameter). In probing mode, they have been used to record neural activity in honeybee brain and frog sciatic nerve (12 channels with terminals down to 1 μm diameter on a variety of probes down to 3×3×100 μm). In enclosure mode, these sensors are being developed with holes etched through the microterminals to allow neural and bacterial cells to grow within each terminal aperture (12 channels with apertures down to 5 μm diameter on probes down to 30×50×500 μm). These devices have been modified by the addition of biochemical-compatible surfaces to create sensors for the monitoring of a wide range of medically important analytes, especially oxygen, glucose and a range of neurotransmitters. The probes are micromachined with chemical etchants, plasmas, ion beams and laser beams. Sculptured carbon surfaces and electropolymerised pyrrole, for the attachment of enzymes, are illustrated.