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The jfish Peripheral Nerve Stimulator

About Specs How Build Use

What can the jfish PNS do?

The jPNS possesses almost all of the features of a comparable, yet expensive, commercial device, at a fraction of the cost. Where commercial units cost upwards of US$400, the jPNS can be built for under US$30 in single-unit quantities.

Features and Specifications

  • Battery powered, running from a standard 9 volt battery. A single 9V cell will provide approximately 100 hours of standard use, depending on conditions. Future versions are planned to use more readily available 1.5V cells.
  • Selectable delivery of the four standard pulse patterns, namely:
    • Single twitch
    • Train of four (TOF)
    • Post tetanic count (PTC)
    • Double burst stimulation (DBS)
  • Current pulses are true monophasic square waves with a consistent 100 ms duration.
  • Delivers a user selectable current up to 65 mA with an automatically determined potential difference up to 300 V.
  • Provides constant current irrespective of skin impedance, up to 4.6 KOhms.
  • Visual (yellow LED) and audible indication of pulses.
  • Low-power mode turns off high-voltage stage to conserve battery life between pulse runs.
  • Output-stage DC-decoupling protects patient from DC-burns in the event of component failure.
  • Low-battery warning LED (red)
  • Low cost and simple construction - the jPNS requires under US$30 in parts and is easily buildable with only intermediate-level electronics experience.
  • Open design and maintenance documents make troubleshooting and fault diagnosis straight forward. Device testing is quick and painless.


Most importantly the open and free design of the jPNS allows easy extension, improvement and even integration with other systems.

  • New and complex pulse patterns can easily be defined, requiring only an update of jPNS software/firmware.
  • Duration of current pulse can easily be increased or decreased as desired, again with only simple firmware modification.
  • Modification to add nerve locator functionality for use in regional anaesthesia is simple, requiring only a single component change and firmware update.
  • Finally, integration with a personal computer or a more complex monitoring system is facilitated by an exposed serial input/output interface. is powered by the excellent Dokuwiki. Hosting, server, OS and design credits.
This work is licensed under a Creative Commons License.

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