Description
DESCRIPTION
DS7A & DS7AH HV Current Stimulators are suitable as general purpose electrical nerve or muscle stimulators for human stimulation and are medically CE marked in the UK/EU and 510(k) FDA cleared within the USA. The DS7A provides up to 100mA constant current high voltage pulses of brief duration for trans-cutaneous stimulation during investigation of the electrical activity of nerve and muscle tissue. The DS7A is also commonly used in psychology, cognitive neuroscience and pain research applications. The output current is continuously variable over the range 0 to 100mA from a maximum compliance voltage of 400V. For more demanding applications, 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. For those who require the high currents of the DS7AH along with the flexibility to use pulses of up to 2ms, we now offer the new DS7R and DS8R research stimulators.
To reduce tissue polarization and in response to customer demand, current models of the DS7A and DS7AH include a three position (+ve, alternating and -ve) polarity control, allowing the user to reverse stimulus polarity or automatically alternate polarity between successive stimuli. The instrument is mounted in a non-conductive, free standing case and is mains powered. The stimulator requires a TTL trigger pulse input and triggers on the positive edge (negative edge can be factory set). Alternatively a foot switch may be connected to a socket on the rear panel or the front panel push button pressed. A TTL compatible trigger output is provided at a BNC socket on the rear panel.
For higher voltages we recommend the D185 MultiPulse Transcranial Cortical Stimulator.
While the DS7A and DS7AH do not permit any external control of the stimulus parameters, anyone interested in this sort of capability should refer to our DS8R Biphasic Research Stimulator, which offers the same output capabilities as the DS7AH, but adds truly biphasic output and multiple options for external control of all pulse parameters.
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Product Information
References
Publications which cite use of the Digitimer DS7A & DS7AH can be found on Google Scholar.
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ACCESSORIES
Supplied
- Mains (Power) lead
- Operator’s Manual
Recommended
FAQS
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.
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.
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.
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.
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.
The DS7A/AH triggers on the +ve edge of a standard TTL compatible logic pulse (+3V to +15V) of at least 5µs duration.
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.
Yes, it is possible to do this and the method has been summarized in an application note.
