The DS8R Biphasic Constant Current Stimulator is a new multi-mode, discrete pulse, constant current stimulator for human research studies involving nerve and muscle stimulation via surface electrodes. It features a high compliance voltage and can be triggered by a TTL compatible input, contact closure foot/hand switch or front panel “single-shot” button. The DS8R can deliver monophasic or biphasic pulses of up to 2ms duration, with an output range of 0-1000mA in 100µA steps (from 400V), however the actual current achieved will be restricted by a pulse energy limit of 300mJ per pulse and the skin/electrode resistance. Most importantly, the new DS8R incorporates features that allow external “on the fly” control of stimulus pulse parameters.
Optional Firmware for High Frequency (10kHz) Stimulation
A special edition firmware can also be provided for researchers interested in stimulating at higher frequencies (10kHz) than the standard unit permits. For example transcutaneous spinal cord stimulation (TSCS) protocols inspired by “Russian” stimulation” methods are possible with this optional firmware, allowing researchers involved in spinal cord injury research to examine the effects of TSCS on recovery of function.
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The 300mJ/pulse limit is present in the EN 60601 international standard and is applicable to medical electrotherapy devices. While the DS8R is intended for research use only, we felt it was prudent to limit the DS8R to a pulse energy that could be applied to a comparable medical device.
No, the DS8R is a triggered pulse stimulator, so the output can only be rectangular in shape. If you need to stimulate with non-rectangular waveforms, please see our DS5 Bipolar Current Stimulator.
Early versions of the DS8R had a minimum pulse amplitude of 2mA, however, from March 2019, all DS8R’s offer a current range of 0-1000mA and can delivery stimuli in the range of sensory thresholds.
Yes, but because of the temporal unreliability of USB communication, we limit the frequency to no more than 10Hz when triggered by the button in the software or via the API.
The standard DS8R can be triggered at a maximum frequency of 1000Hz, however, we have provided a modified firmware to some users which allows the DS8R to be triggered at 10kHz, allowing it to deliver bursts of biphasic pulses with 50us phase durations and <1us phase intervals. This has been employed for applications such as transcutaneous high frequency stimulation of the spinal cord, in order to research rehabilitation following spinal cord injury. Please contact us if you have an interest in this non-standard firmware.
The DS8R is supplied with our own Windows compatible Virtual Front Panel GUI software, which allows the user to control all settings accessible from the physical front panel, including triggering at up to 10Hz. As part of the software installation, an API is included which offers a basic but versatile programming interface to the DS8R. Third party control of the DS8R has been implemented by Cambridge Electronic Design (CED) in the latest versions of their Signal and Spike2 software and we also provide a Matlab solution in the downloads section of this page. Note that we have a web forum for hardware and software discussion.
While Digitimer does not have expertise in Python development, we do know of DS8R users who have implemented control. A solution developed by Hoyuong Doh, Woo-Young Ahn and Jaeyeong Yang (Seoul National University, Republic of Korea) enables control of the Digitimer DS8R Constant Current Stimulator using Python 3.5 or higher and 64-bit Windows machines. This repository is a Python porting of cocoanlab/DS8R_matlab, based on work by Dr. Choong-Wan Woo and Sungwoo Lee in the COCOAN laboratory.
Digitimer does not develop software for any platform other than Windows, but it may be possible to use a Windows emulator. If not, the DS8R does allow external control of triggering via a TTL/digital input and stimulus amplitude via an analogue input.