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Current or Voltage Linear Isolated Stimulator

Current or Voltage Linear Isolated Stimulator

The STMISOLA Constant Current and Constant Voltage Isolated Linear Stimulator can output either voltage or current waveforms and provides considerable flexibility in stimulation protocols.

Linear stimulatorgenerate stimulation signals that can have arbitrary waveshape. Typically, stimulators can only generate simple unipolar or bipolar pulses. The STMISOLA, however, can output unipolar or bipolar arbitrary waves such as pulse (single or train), square, sine, triangle, exponentially decaying, modulated envelopes, and fully user-specified types.

Voltage and current stimulator (unipolar or bipolar)—Voltage mode multiplies the input voltage x20, output Current mode has two options: High current (gain factor of 10 ma/volt) or Low Current (gain factor of 1 ma/volt); Low current mode permits much improved control for currents less than 10 ma.

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Linear Isolated Stimulator Constant Current/Voltage
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Categories: Stimulation - Research
Subcategories: Stim Isolation Adapters - Research, Stimulators - Research



The STMISOLA connects directly to

  • MP36 or MP36R analog output signal drive  ±10 V input
  • UIM100C (associated with the MP1X0 system) Analog Output 0 or 1 port
  • STM100C 50 Ω output port

The STMISOLA ships with cables to allow additional connections

  • Includes 3.5 mm to 3.5 mm cable (CBL100) for connection to Digital I/O on the UIM100C rear panel
  • Includes Y-Splitter (CBL212) to permit the MP150 to sample the drive waveform from stimulus presentation setups; permits recording of the drive waveform timing and amplitude

Voltage (V) mode—the STMISOLA multiplies the Control Input Voltage by a factor of 20, to present that amplified signal at the STMISOLA output.

In the case of a maximum ±10 V Control Input Voltage, the STMISOLA will output a ±200 V signal, with an output impedance of either 100 ohms or 1 K ohms. These output impedance settings will act to limit the available output current.

Current (I) mode—two settings:

        The STMISOLA provides two options for output current mode.

    1. High current mode (Zout switch set to 100 ohms), provides a gain factor of 10 ma/volt.
    2. Low current mode (Zout switch set to 1 K ohms), provides a gain factor of 1 ma/volt.

        The STMISOLA multiplies the Control Voltage by the factor indicated (K in ma/V) to present that associated output current at the STMISOLA output.

In the case of a maximum ±10 V Control Input Voltage, for:

Zout = 100 ohms, K=10 ma/V:  the STMISOLA will output ±100 ma

Zout = 100 ohms, K=1 ma/V:  the STMISOLA will output ±10 ma

In both cases, the voltage compliance is ±200 V.

For transcranial direct current stimulation (tDCS), the STMISOLA will support arbitrarily long, constant, non-varying, direct output currents, so long as the associated voltage compliance is 100 VDC or less. The tDCS level is adjusted by holding a stable voltage to the control voltage input of the STMISOLA. The control voltage can be set in AcqKnowledge, to be output to STMISOLA via MP150 analog output.  tDCS neuro-stimulation typically employs the use of low level (typically under 2 ma) constant, unipolar, direct current.

Isolation characteristicsThe STMISOLA isolates the Control Input Voltage signal from the stimulus output to 1500 VDC HiPot and approximately 1000 pF of coupling capacitance.

This very high degree of input/output isolation helps ensure subject safety and helps considerably to substantially reduce, or eliminate, stimulus artifact.

Stimulus artifact results when some percentage of electrical current from the stimulation site is directed to the recording site due to electrical leakage paths intrinsic to the stimulation/recording equipment. In the case of the STMISOLA, the leakage conductance and capacitance that permit this artifact to occur are reduced to very small values.

Power ON SafetyWhen you Power ON the STMISOLA, you must also hold Reset for at least 3 seconds. This forces the unit into an “operational but no output state” and protects the subject if accidentally connected to electrodes on power up.

IMPORTANT Comprehensive Safety Guidelines for Performing Electrical Stimulation on Subjects: read Application Note 257 – Safe Use of Electrical Stimulators




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