A 24 Vpp compliant biphasic stimulator for inductively powered animal behavior studies

Stimulation of biological neurons using electrical charges has gained popularity in neuro-engineering studies. Wireless power delivery to electrical stimulators is an essential requirement for long term and maintenance-free implantable applications. Voltage compliance is often a limiting factor in these systems. We present an inductively powered biphasic stimulator that is capable of exhibiting 24 V_pp load voltage compliance, while harvesting up to 13 V. The stimulator can deliver currents ranging from 10 μA to 6 mA. The inductive energy harvesting system operates at a low carrier frequency of 134.2 KHz for enhanced depth of penetration in biological medium. The near-field harvester works reliably for up to 50 mm inter-antenna distance. Noise performance and charge balancing accuracy have also been improved due to the absence of a boost switching circuit and floating current source based architecture. In-vivo motor and visual cortex stimulations have been performed using epi-dural screw electrodes on an awake behaving and anesthetized Wister rat.