Battery powered neuromuscular stimulator circuit for use during simultaneous recording of myoelectric signals

Research output: Contribution to journalArticle


Surface Functional Electrical Stimulation (FES) requires high stimulation voltages. A step-up transformer in the output stage of the stimulation circuit is often used. In the present technical paper a voltage controlled current source (VCCS) is presented as an alternative to the transformer coupling. Two (master-slave) coupled transconductance amplifiers (TAs)-in series with pre-charged capacitors-are used to drive the output current. After each stimulation pulse the capacitors are recharged to a high voltage by a switch mode power supply (SMPS). A multiplexer in the output stage is used to provide biphasic output. Output rise-time (10-90%) was less than 2 μs at 100 mA output. Biphasic charge balanced stimulation current can be produced with a net current to ground of less than 20 nA, thus virtually separated from ground. The circuit permits recording of the volitional myoelectric signal from the stimulated muscle. It is part of a portable myoelectrically controlled FES system powered by 2 AA batteries and currently used in clinical trials.

Original languageEnglish
Pages (from-to)1032-1037
Number of pages6
JournalMedical Engineering and Physics
Issue number8
Publication statusPublished - Oct 2009



  • Battery powered
  • Biphasic stimulation
  • Functional Electrical Stimulation
  • Myoelectric signals
  • Portable
  • Stimulation artifacts
  • Stimulation circuit

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biophysics

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