TASER Electronic Control Devices Review Of Safety Literature

Sample Motor Neuron Transcutaneous Capture Threshold
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Current (amperes)
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0 50 100 150 200 250 300 350 400 450 500
Duration (microseconds)
Figure 4 The threshold in amperes for the capture of the A-α motor neurons as a function
of the pulse duration. Note that narrow pulses require much more current.
Figure 4 shows a representative strength-duration curve for widespread transcutaneous
stimulation of A-α motor neurons which control skeletal muscle contraction.
The rheobase for A-α motor neurons is approximately 1 A (ampere) with a
chronaxie of 100 µs (microseconds). In contrast, the cardiac chronaxie, for
transcutaneous stimulation, is 3–5 ms (milliseconds) or 30–50 times longer in
pulse duration.
Figure 5 shows the relative energy requirements to capture the A-α motor neurons
with different pulse widths. Note that the most energy efficient pulse width is
about 100 µs.
Figure 5 The threshold in mJ (millijoules) for the capture of the A-α motor neurons as a
function of the pulse duration.
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