A silicon probe with integrated microheaters for thermal marking and monitoring of neural tissue

This paper describes a microheater structure and its integration on a silicon microprobe. The 30-μm-diameter microstructure can be used to heat local areas of tissue or to measure local tissue temperature with an accuracy of <0.3°C. The polysilicon microheater is suspended on a dielectric membrane to reduce undesired heat conduction to the probe substrate. The heating efficiency is 4.4°C/mW in still water and 2.2°C/mW in guinea pig cortex. Six milliwatts applied for 2 min in cortex produces a temperature of 50°C, creating a well-defined 50-μm-wide lesion for determining probe position histologically. Fabrication of the heaters requires no additional masking or processing steps in addition to those normally used for recording or stimulating probes.