Suitable as a general purpose electrical nerve or muscle stimulator, the DS7A provides up to 100mA constant current high voltage pulses of brief duration for percutaneous stimulation during investigation of the electrical activity of nerve and muscle tissue. The DS7A is also commonly used in pain research applications. The output current is continuously variable over the range 0 to 100mA from a maximum compliance voltage of 400V. The DS7AH allows currents up to 1A with a reduced maximum pulse duration limit of 200µs. This model is offered to overcome the difficulties of stimulating deep peripheral nerves, or large muscles such as the quadriceps with large area electrodes.
Since April 2014, the DS7A and DS7AH have included an alternating polarity mode to prevent polarization of the stimulation site and potentially harmful electrolytic effects of longer periods of stimulation.
The DS7A or DS7AH can be triggered by an external device such as our new DG2A Train/Delay Generator. For applications that require a higher output, we recommend our D185 MultiPulse. The DS7A & DS7AH are CE marked medical devices and have been cleared by the FDA for marketing within the USA.
- Pulse durations from 50µs to 2ms (DS7A) and 50µs to 200ms (DS7AH).
- 100mA (DS7A) or 1A (DS7AH) constant current output from 400V.
- Flexible TTL compatible trigger options or front panel push button.
- NEW Alternating Polarity control – a toggle switch allows the stimulator to operate in +ve, -ve or alternating polarities during stimulation.
- Output connection accessories, including plugs and cables and electrodes are also available.
1. I am trying to decide whether I need to use the DS7A or DS7AH, do you have any advice?
The maximum output of the DS7A is 100mA while that of the DS7AH is 1A (with reduced output widths). We find that for the majority of applications, the DS7A is perfectly suitable, however, the main exception is where the human quadriceps muscle is being directly stimulated. In this particular case, we would recommend the higher output of the DS7AH.
2. I want to produce trains of electrical stimuli and the DS7A does not include a frequency generator, does Digitimer have a simple device which could be used for this purpose?
Of course we do. Digitimer manufactured several devices suitable for this. Certain configurations of the NeuroLog system can be used to generate quite complex trigger pulse protocols compatible with the trigger input of the DS7A/AH. However, our battery powered DG2A Train/Delay Generator complements the DS7A/AH by providing a continuous burst of trigger pulses with control over frequency.
3. I want to stimulate using pulses of alternating polarity, is this possible with the DS7A?
The current production versions of the DS7A/AH stimulators now have the facility to alternate the polarity of the pulses in a burst. With this new feature, the DS7A/AH can produce +ve going, -ve going or alternating polarity pulses through the use of a three position toggle switch.
4. What sort of output plugs do I need in order to connect electrodes to the DS7A stimulator?
The DS7A and DS7AH are not supplied with output plugs, however we do provide them as optional accessories. The part code for a pair (one red, one black) is D185-OC1.
5. Does Digitimer supply a range of electrodes for use with their stimulators?
Digitimer does now offer a range of Neurodiagnostic accessories to be used with our stimulators and amplifiers. We appreciate that we cannot include all types of electrode, so If you experience difficulty obtaining electrodes of the correct specifications, we would be glad to help.
6. I am planning to trigger a DS7A using a computer DA interface. What are the requirements for the trigger pulse?
The DS7A/AH triggers on the +ve edge of a standard TTL compatible logic pulse (+3V to +15V) of at least 5µs duration.
7. I have one of your DS7A stimulators, but the pulse duration control knob doesn’t turn to the 0.5-2ms settings, should I return it for repair?
The higher output DS7AH has a limiting feature that for safety reasons prevents use of these wider pulse durations. Although your stimulator has DS7A on the front panel, please check the serial number label on the back of the unit, as I think you will find it indicates that it is a DS7AH.
8. Is it possible to use two DS7A stimulators in parallel to stimulate a subject with a pair of different pulse types through the same set of electrodes?
Yes, it is possible to do this and the method has been summarized in an application note.
DS7A & DS7AH
Publications which cite use of the Digitimer DS7A/AH can be found on Google Scholar.
- Mains (Power) lead
- Operator’s Manual
- D185-HB4 Output Extension Cable
- D185-OC1 Output Connection Plugs
- DG2A Train/Delay Generator
- DS7A-HS1 Hand-switch for remote triggering
- Electrodes & Accessories
Assessment of Neuromusclular Function Using Electrical Nerve Stimulation
Goss, D. A., Hoffman, R. L., Clark, B. C. Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System. J. Vis. Exp. (59), e3387, doi:10.3791/3387 (2012).
Li, S. Breathing-controlled Electrical Stimulation (BreEStim) for Management of Neuropathic Pain and Spasticity.J. Vis. Exp. (71), e50077, doi:10.3791/50077 (2013).
Kindt, M., Soeter, M., Sevenster, D. Disrupting Reconsolidation of Fear Memory in Humans by a Noradrenergic β-Blocker. J. Vis. Exp. (94), e52151, doi:10.3791/52151 (2014).