An experimental study of voltage, current, and charge controlled stimulation front-end circuitry

We have developed an experimental 4-channel stimulator prototype capable of performing voltage controlled stimulation (VCS), current controlled stimulation (CCS), and switched capacitor based stimulation (SCS) all on the same platform for neurological experiments. The stimulator allows changing main stimulation parameters such as amplitude, pulse width, pulse frequency, and output channels in real-time either wirelessly or hardwired. The stimulator was used to objectively evaluate the power efficiencies of each stimulation strategy using platinum epilepsy electrodes with 2.3 mm(2) exposed area in saline solution. We measured 92%, 65%, and 77% efficiencies for VCS, CCS, and SCS, respectively, on a 962 Omega - 810 nF resistive-capacitive load. The motivation behind this research is to find the most power efficient stimulation front-end (SFE) circuitry for implantable neurological stimulators (INS).