The DS5 isolated bipolar stimulator allows computer control of stimulus amplitude and timing parameters and has a maximum constant current output of ±50mA. It has been designed to speed up and enhance human peripheral nerve diagnostics by facilitating semi-automated nerve excitability tests. It also has roles in wider aspects of clinical neurophysiology research, including psychological, vestibular system and nociceptive testing. The DS5 is a CE marked medical device under the European Medical Device Regulation.
The DS5 can be controlled by an analogue voltage input which it translates into an isolated constant current stimulus (up to ±50mA), precisely replicating the shape of the input waveform. As a result the DS5 should be of interest to anyone wishing to control surface stimulation protocols via software/hardware combinations capable of producing a suitable command voltage waveform e.g semi-automated pain research or sensory threshold testing. The DS5 has also been employed for galvanic vestibular stimulation (GVS) and transcranial AC stimulation (tACS) protocols.
The DS5 was developed in collaboration with Prof. Hugh Bostock (UCL, London) for use with QtracW, a nerve excitability stimulus control, acquisition and data analysis software package.
- Up to ±50mA output from ±120V compliance, in 3 output ranges.
- Isolated constant current output proportional to input “command” voltage.
- Compatible with DAQ’s capable of producing an analogue voltage output.
- Safety features ensure patient/human subject protection. CE marked medical device.
- Output connection accessories, including plugs and cables and electrodes are also available.
I am interested in purchasing a DS5 stimulator, but I am not sure how I would control it, can you help?
The DS5 has been designed to be as versatile as possible and therefore it should be compatible with most D/A hardware and software. The DS5 merely requires an analogue input of ±1, ±2.5, ±5 or ±10V at the BNC socket on the rear to provide the waveform which describes the stimulus. However, the user should note that they will need to source or write software that allows them to define the characteristics of the waveform.
Is it possible to control the settings of the DS5, such as output ranges via remote devices/software?
Yes, we have developed GUI control software that allows this to be possible, you can download from this website.
3. I see that the DS5 is limited to 50mA, is there the possibility to modify it for a higher output current?
No, after taking advice from collaborators we decided that a ±50mA limit was adequate for most cases, however, it is possible to link two DS5’s together in parallel to increase the overall stimulus output. Please contact us for details.
I am currently using the DS5 but have found it difficult to re-enable the output after auto-zeroing and sometimes have to attempt this several times, is there a problem with my stimulator?
It is likely that the failure to re-enable the output is accompanied by a warning icon which indicates that re-enabling would result in DC stimulation. If this is the case, then the cause is almost certainly due to (i) a voltage waveform still being applied at the voltage input during the auto-zeroing procedure or (ii) noise being picked up through the input socket. For safety reasons, the DS5 will not re-enable if a significant stimulus current would immediately result.
I see there is a USB socket on the back of the DS5, what is this for?
This socket served two purposes – (i) It allows the operator to upgrade the firmware of the DS5 and (ii) it provides the communication link to control the DS5 settings from PC software. The DS5 User interface software can be downloaded from the Downloads tab on the DS5 product page. Do not connect the DS5 to the PC via the USB cable until this software has been installed.
What is the minimum interval between stimulation “pulses” using the DS5?
The DS5 will identify the end point on a stimulation pulse as the stimulus current value falling to within ±400µA for a minimum period of 200µs or a sustained reversal of stimulus polarity (irrespective of the current amplitude). Therefore if you intend to carry out repetitive stimulation pulses of the same polarity, there needs to be a 200µs gap between them. If the pulses are of alternating polarity, there is no requirement for an interval (e.g as in a sine wave).
I switched on my DS5 and started using it, but found that the baseline output drifted considerably for the first 30 minutes, even though the voltage input was zero. Why is this?
As with many electronic instruments, certain components within the DS5 make it important that the stimulator is switched ON and “warmed up” for at least an hour before it is used with a subject.
I am considering using the DS5 for some studies of rodent nerve excitability. Is the DS5 suitable for this?
The DS5 is designed for use with human nerves in vivo and as such the sort of currents it generates are in the mA range. Even when the output of the DS5 has been recently autozeroed, some small currents (in the µA range) can persist and while these would be insignificant for human studies, they may be unwelcome in the rodent equivalent. Instead, we would recommend our DS4 stimulator for such non-human research studies.
I have noticed that the DS5 is making a beeping noise when I am delivering stimuli, can I turn this beeping off?
The DS5 produces two types of audible alert. A high pitched “information” beep serves as confirmation that the operator has toggled or pressed a front panel switch or button. A deeper pitched “warning” tone informs the operator that a safety limit has been reached/exceeded or that intervention is required in response to a warning icon which will be simultaneously displayed on the front panel screen. Audible alerts are switched on by default, but the “information” beep may be disabled by the user via the options menu. When disabled a icon is displayed on the front panel LCD screen. If the DS5 beeps during stimulation, it is likely that there is a problem which the operator should investigate, such as an out of compliance error. The operator should check the LCD display for an information icon, which will explain why the warning is being given.
DS5 Control Software
DS5 – Isolated Bipolar Constant Current Stimulator
Publications which cite use of the Digitimer DS5 can be found on Google Scholar.
- Mains (Power) Lead
- Operator’s Manual
- USB Cable
- D185-HB4 Output Extension Cable
- D185-OC1 – Output Plugs
- Electrodes and electrode adaptor leads