Continuous-waveform constant-current isolated physiological stimulator

Abstract

We have developed an isolated continuous-waveform constant-current physiological stimulator that is powered and controlled by universal serial bus (USB) interface. The stimulator is composed of a custom printed circuit board (PCB), 16-MHz MSP430F2618 microcontroller with two integrated 12-bit digital to analog converters (DAC0, DAC1), high-speed H-Bridge, voltage-controlled current source (VCCS), isolated USB communication and power circuitry, two isolated transistor-transistor logic (TTL) inputs, and a serial 16 × 2 character liquid crystal display. The stimulators are designed to produce current stimuli in the range of ±15 mA indefinitely using a 20V source and to be used in ex vivo cardiac experiments, but they are suitable for use in a wide variety of research or student experiments that require precision control of continuous waveforms or synchronization with external events. The device was designed with customization in mind and has features that allow it to be integrated into current and future experimental setups. Dual TTL inputs allow replacement by two or more traditional stimulators in common experimental configurations. The MSP430 software is written in C++ and compiled with IAR Embedded Workbench 5.20.2. A control program written in C++ runs on a Windows personal computer and has a graphical user interface that allows the user to control all aspects of the device.

ElectricItch

“…Itching only requires lower currents and thus more basic designs can be used. We base our design on a boost converter and h-bridge combination already used successfully in previous work [8,16,57,58,61]. Where we use a constant current source for current regulation (similar to [7,50]), more efficient closed-loop designs are possible [36].…”

StimDuino: An Arduino-based electrophysiological stimulus isolator

“…Recently, several microcontroller-based stimulus isolators have been proposed (Holcomb et al, 2012;Land et al, 2004). The usage of microcontrollers allows automating the experimental protocol and overcoming the limitations of many manually-controlled stimulus isolators.…”