High‐voltage compliant microelectrode array drivers for intracortical microstimulation

Abstract

SUMMARYWe present in this paper two low-power high-impedance microelectrode array drivers (MEDs) dedicated for visual intracortical microstimulation. These output stages of a new microstimulator are highly configurable and able to deliver higher compliance voltage (20 V for anodic and cathodic phases) across microelectrode-tissue interface impedance compared with previously reported designs. Each MED is featured with a high-voltage switch-matrix, 3.3 V/20 V current mirrors, an on-chip 32-bit serial-in parallel-out shift register, and the new forbidden state logic circuits. Both systems are able to deliver eight bipolar or 16 monopolar stimulation simultaneously. The first MED is able to deliver one stimulation current level and the second one provides four different current amplitudes simultaneously to 16 electrodes. Two microchips have been designed and fabricated using Teledyne DALSA 0.8 μm 5V/20V double-diffused metal-oxidesemiconductor field-effect transistor (Teledyne DALSA Semiconductor, Bromont, Québec, Canada) technology to meet the required high-voltage compliance. The nominal values of largest supply voltages are ±10 V. The maximum stimulation current per input channel is 400 μA and per output channel through an emulated microelectrode impedance of 100 kΩ is 100 μA. The measured output compliance voltage is 10 V/phase (anodic or cathodic) for the specified supply voltages. Increment of supply voltages to ±13 V allows 220 μA stimulation current per output channel enhancing the output compliance voltage up to 20 V/phase. The measured quiescent power consumptions of the proposed microelectrode array drivers are 316 and 735 μW, respectively. Post-layout simulation and measurement results of two MEDs and comparison with other designs have been reported in this paper.

A high‐voltage stimulation chip for wearable stroke rehabilitation systems

“…Although the circuits have good driving capability under a high supply voltage, their controllability is limited, and the high power consumption and the large size are not suitable for wearable systems. In [20,22] and [25][26][27], integrated circuits are designed for functional electrical stimulators. The work in this paper achieves the highest-voltage compliance and the largest-current drivability.…”

“…To guarantee the current drivability even in case of high impedance at the load, a voltage booster that generates a 17 V voltage supply is also integrated into the chip. To achieve higher voltage compliance and higher output impedance, Maghami (2014) and Hasanuzzaman et al (2015) [21,22] adopt the active cascode structure in the current driver, but the output current with maximum of 400 μA is not enough for limbs surface stimulation.…”

Direct Growth of Carbon Nanotubes on New High-Density 3D Pyramid-Shaped Microelectrode Arrays for Brain-Machine Interfaces

“…To measure the charge injection capacity ( Q inj ) of the microelectrodes, we interfaced the MEAs with a novel microstimulator designed in our laboratory [ 41 , 42 ]. The MEA was immersed in 0.9% PBS solution, then charge-balanced and biphasic constant current was applied to different pairs of microelectrodes.…”

High-density 3D pyramid-shaped microelectrode arrays for brain-machine interface applications

“…A scan rate of 50 mV/s was used. To measure charge injection capacity (Qinj) of microelectrodes, we interfaced the MEAs with a novel microstimulator designed in our Laboratory [156,157]. The MEA was immersed in 0.9% PBS solution then charge-balanced and biphasic constant current was applied to different pairs of microelectrodes.…”