The DS8R is a new constant current, multi-mode, discrete pulse 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 and 0-1000mA (at up to 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.
Biphasic Charge-balanced Output
The DS8R has two pulse modes, enabling stimulation using monophasic or biphasic rectangular pulses. Additionally, in biphasic mode the DS8R allows for both symmetric or asymmetric charge-balanced stimuli through implementation of an adjustable stimulus/recovery phase amplitude ratio. Biphasic charge-balanced stimulation offers certain advantages over monophasic stimulation, as it prevents the potentially harmful electrochemical changes which occur under stimulation sites and is reported to be more comfortable for the subject during long periods of stimulation. The recovery phase ratio can be adjusted from 10% to 100% in 1% increments. As illustrated below, at 100% the two phases are identical in terms of duration and amplitude, but as the ratio is reduced from 100% the amplitude of the recovery phase decreases, while its duration is extended to preserve charge balancing.
External Control Capabilities – Software (via USB) and Analogue Voltage Input
Researchers often want to adjust stimulus settings (current and duration) during a stimulation protocol and with the arrival of the DS8R, such control becomes a reality. While the DS8R can operate as a standalone isolated stimulator with full control via the front panel, settings can also be modified using Windows PC control software (supplied) via a USB interface. This software provides a Virtual Front Panel for the stimulator, but more importantly incorporates an API allowing the operator to implement control from custom or commercially available software packages.
Pulse current amplitude can be more simply controlled via an analogue voltage input (BNC) on the rear of the DS8R. Using this method of control, the DS8 monitors the voltage applied at this input (0-10V) and adjusts the stimulus current (0-1000mA) proportionally with this voltage as each trigger input is detected. Note that the control voltage signal does not define the shape of the output pulse, it is merely used as a proportional representation of the output stimulus current.
The DS8R is suitable for human research applications, but because the maximum pulse energy of 300mJ exceeds the 50mJ limit imposed by the international standard for diagnostic stimulation devices, we are not seeking medical device certification for the DS8R. If you have a requirement for a medically certified equivalent of the DS8R, please contact us to express your interest.
- Current range 0-1000mA from up to 400V
- Pulse duration range 50-2000µs
- Biphasic Output – Charge-balanced symmetric or asymmetric
- Adjustable inter phase interval (0-50ms)
- External control via PC software/USB connection (includes API)
- Analogue Control of Stimulus current
- PC log of stimulus parameters stored in CSV format
- Output connection accessories, including plugs and cables and electrodes are also available.
1. The DS8R is limited to a maximum pulse energy of 300mJ, why was this value chosen?
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.
Not available yet
As the DS8R is a new product we do not have any publications yet.
- Mains (Power) lead
- Operator’s Manual
- GUI Software (USB Flash Drive)
- USB Cable
- D185-HB4 Output Extension Cable
- D185-OC1 Output Connection Plugs
- DG2A Train/Delay Generator
- DS7A-HS1 Hand-switch for remote triggering
- Electrodes & Accessories