Evoke
®
SCS System Clinical Manual
CLIN-UMAN-005175
Revision: 9.00
Page 37 of 101
7
Clinical Interface – Programming features
7.1
Stimulation Waveform
Each stimulation waveform consists of constant current, actively charge-balanced, pulses. The
output current is automatically controlled when closed-loop is enabled, and set to a fixed level
when closed-loop is disabled. The stimulation waveform can be customized (see Figure 7.1 for
example) by the selection of the following parameters: pulse shape, polarity, stimulation
current, and pulse timing.
Figure 7.1: Example stimulation waveform for a program with two stimulation sets.
Stimulation set A is shown with triphasic and positive-first, and stimulation set B is shown
with biphasic and negative-first. Each stimulation set may also have a different stimulation
current, pulse width, and interphase gap. The inter-stimulus interval is configurable for each
program.
7.1.1
Pulse shape and polarity
Each pulse can be configured to have two (biphasic) or three (triphasic) phases, and to either
start with a positive phase (positive-first) or negative phase (negative-first). The pulse shape
and polarity can be customized for each stimulation set (see Section 8.6 to set the pulse shape
and polarity, and Figure 7.1 for examples).
7.1.2
Stimulation current
When closed-loop is disabled, the stimulation current is fixed at the level chosen by the user
(see Section 6.9). When closed-loop is enabled, the stimulation current is automatically
adjusted in response to the difference between the ECAP amplitude and the target level chosen
by the user (see Section 6.14). The stimulation current can be customized for each stimulation
set (see Section 7.5.3, e.g. Figure 7.1), such that the ratio of stimulation currents between each
stimulation set is kept constant.
