Clinical Multichannel Constant-Current FES Stimulator
Delivers programmable charge-balanced biphasic current pulses from 1 to 50 mA with 250 μs duration.
Biomedical Engineering / FES Biphasic Charge Balance
FREE TO EXPLORELABORATORY 41 · BIOMEDICAL ENGINEERING
Biphasic Functional Electrical Stimulation (FES) Charge Balance & Injection
Verify net zero electrochemical charge balance and evaluate cathodic phase charge injection Q_p as a function of stimulus pulse current I_stim in a Functional Electrical Stimulation (FES) neuroprosthesis. Explore interactive physiological instrumentation simulation, biomechanics, and biomedical engineering telemetry.
BIOINSTRUMENTATION · BIOSIGNALS · BIOMECHANICS · IMAGING
Your virtual biomedical engineering laboratory.
CATHODIC PHASE INJECTED CHARGE Q_P—
PHYSIOLOGICAL & TEST CELL TELEMETRY
Ready to sample with Current I_stim = 15.0 mA.
Adjust Current I_stim, then execute biomedical trial.
Biomedical engineering telemetry and physiological states are evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity biological and physiological modeling.
Biomedical assumptions and boundary condition limits
The simple Q = I · t relationship assumes a perfect rectangular current pulse; real inductive leads introduce finite rise and fall times. Evaluated on a clinical constant-current FES neuroprosthesis (Bioness NESS L300 architecture) delivering charge-balanced symmetric biphasic rectangular pulses (pulse duration t_pw = 250 μs = 0.2500 ms, frequency 35 Hz) into a 1.0 kΩ parallel RC tissue load in 37.0 °C saline. Cathodic injected charge slope t_pw = 0.2500 μC/mA across pulse currents I_stim from 5.0 to 30.0 mA.
Biomedical apparatus & physiological sensors.
Platinum-Iridium Neurostimulation Electrode Pair (10 mm²)
Biocompatible stimulation electrodes with high capacitive charge injection capacity (Q_inj).
Electrochemical Tissue Impedance Load Phantom (1.0 kΩ || 10 nF)
Accurately models transcutaneous skin-electrode interface impedance and double-layer capacitance.
Precision Current-Sense Resistor & Analog Integrator Circuit
Integrates current waveforms in real time to measure injected phase charge Q_p with 0.01 μC accuracy.
High-Resolution Dual-Channel Digital Oscilloscope
Captures simultaneous cathodic and anodic phase waveforms and monitors residual DC charge balance.
Thermostatically Controlled Physiological Saline Bath (37.0 °C)
Maintains 0.9% NaCl electrolyte environment for electrochemical electrode testing.
FOLLOW THE METHOD
A reason behind every step.
Verify net zero electrochemical charge balance and evaluate cathodic phase charge injection Q_p as a function of stimulus pulse current I_stim in a Functional Electrical Stimulation (FES) neuroprosthesis. Standardized parameter settings: 5.0, 10.0, 15.0, 20.0, 25.0, 30.0 mA.
01
Tissue Phantom Load Connection and Calibration
Connect the FES stimulation output across the 1.0 kΩ precision non-inductive load in parallel with 10 nF double-layer capacitor; verify zero DC bias voltage.
02
Biphasic Waveform Symmetry Configuration
Program stimulator to deliver charge-balanced symmetric biphasic pulses: pulse width t_pw = 250 μs cathodic, 50 μs interphase delay, followed by 250 μs anodic reversal at 35 Hz.
03
Initial Current Step Initialization
Set stimulation current amplitude to I_stim = 5.0 mA and initiate continuous stimulation train.
04
Cathodic Phase Charge Integration
Record the voltage drop across the precision 10.0 Ω sensing resistor, integrate current over the 250 μs cathodic duration, and calculate injected charge Q_p = I_stim · t_pw in micro-Coulombs.
05
Net DC Charge Balance Verification
Integrate the complete cycle (cathodic plus anodic phases) over 100 pulses to confirm net DC offset charge is strictly < 0.01 μC (safe charge balance).
06
Current Progression Sequence
Increment stimulation current through 10.0, 15.0, 20.0, 25.0, and 30.0 mA, recording cathodic injected charge Q_p at each current step.
07
Charge Injection Linear Regression Analysis
Plot injected charge Q_p versus stimulation current I_stim and verify that the regression slope matches the programmed pulse duration t_pw = 0.2500 μC/mA.
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into biomedical engineering insight.
Points are your recorded observations. The solid regression line validates FES Biphasic Charge Balance mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
Q_p = t_pw · I_stim = 0.2500 · I_stim (where t_pw = 250 μs = 0.2500 ms)
| # | Stimulation Pulse Current I_stim (mA) | Cathodic Phase Injected Charge Q_p (μC) | Stimulation pulse current I_stim (mA) | Cathodic injected charge Q_p (μC) | Remove |
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