Transcutaneous electrical stimulation devices tests

At the present time, there is only one standard test that evaluates the performance of transcutaneous electrical nerve stimulator (TENS) devices. The rationale for this test is not well documented and its scope and limitations are unclear. The thrust of this paper is to discuss the selected factors that are likely to affect the performance standard. These include stimulus waveform, constant current versus constant current voltage output and electrode size. Each of these parameters have been shown to influence the stimulation output and the conductive characteristics of human tissue. Stimulating with different waveforms significantly affects peak current, peak voltage and total pulse charge, but insignificantly affects the phase charge. Using a different electrode size alter all stimulus output values during excitation of peripheral nerves, indicating tile need to specify electrode size for simulated tissue loads. Data show that a single load is not adequate to simulate the conductive medium of human tissue. Instead a family of loads is considered and their validation for testing conditions is discussed.