Projects / Laboratory and scientific instruments
Laboratory stimulator for neurophysiology experiments: short bipolar pulses with configured duration and current, synchronization with an external recording system and hardware safety limits.
The task was to make a device for scientific experiments where an electrical stimulus is applied to a subject's finger at the exact moment of an external event. After the stimulus, the system had to record the subject response and send logic synchronization signals to a brain-activity recording system.
A laboratory stimulator was developed with configurable pulse amplitude and duration. The device generates bipolar pulses, reacts to a photodetector signal, sends synchronization logic signals and includes protective measures to limit long-duration current.
Project materials
Engineering context
The stimulus has to be short, repeatable and synchronized with external recording.
Pulse amplitude and duration have to be set accurately.
After the stimulus, the subject response has to be recorded as a separate event.
When a device interacts with a person, isolation and hardware current limiting are critical.
Work done
Generation of bipolar pulses with 50-350 us duration.
Current setting in the 1-12 mA range.
Photodetector event input.
Logic signals for an external recording system.
Subject button-press registration.
Isolation transformer and current-limiting stage.
Details
When the photodetector triggers, the device sends a synchronization signal, generates the stimulus and then records the subject response. This makes it possible to relate the external event, electrical stimulus and response in one time sequence.
The device provides controlled current and pulse-duration settings so the experiment is not dependent on manual timing or uncontrolled pulse generation.
The circuit includes isolation and current limiting to prevent long-duration current above the intended safe level. The public description is limited to the engineering role of the device and does not present it as a certified medical product.
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