Electrical Stimulation System with Fast Voltage Rise Time Pulse Control
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Solution Overview
Problem
Existing functional electrical stimulation (FES) devices face limitations in ensuring charge balance over time due to partial control over temporal characteristics and amplitude, leading to discomfort and inefficiency, particularly with slow voltage rise times resulting in high steady-state current.
Innovation Solution
A system and method that utilize a pulse generating circuit with a controllable output voltage to generate constant voltage pulses with exponential decay to a steady-state current value, estimating the resistance element and determining a target steady-state current to achieve the desired stimulation intensity with reduced steady-state current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If slow voltage rise time is used in current regulated pulses, then current delivery is simplified, but steady state current becomes excessively high causing discomfort
Solution Approach 1:
The patent changes the voltage rise time parameter from slow to very fast (10-20 ns), which fundamentally alters the current waveform characteristics. This parameter change reduces the steady state current required to achieve the same stimulation effect, thereby resolving the contradiction between ease of current delivery control and reduction of discomfort-causing steady state current.
Solution Approach 2:
The patent employs periodic pulsed voltage delivery with specific temporal characteristics (rise time, pulse width, frequency) to achieve effective stimulation while minimizing steady state current exposure. The periodic nature of the pulses allows for effective neuromuscular activation without sustained high current levels that would cause discomfort.
2Object-affected harmful factors
If fast voltage rise time (10-20 ns) is used, then steady state current is significantly reduced, but pulse generating complexity increases
Solution Approach 1:
The patent replaces traditional mechanical or electronic voltage regulation mechanisms with a fast switching circuit that generates very fast rise time voltage pulses (10-20 ns). This substitution uses semiconductor switching devices to achieve the fast rise time electronically, simplifying the overall system while achieving the desired fast voltage transition that reduces steady state current.
3Ease of operation
If existing FES devices are used, then basic stimulation is provided, but charge balance cannot be ensured over time due to limited control
Solution Approach 1:
The patent implements a control system that monitors and adjusts stimulation parameters to ensure charge balance over time. By using very fast rise time voltage pulses and precisely controlling pulse temporal characteristics, the system can deliver equal amounts of positive and negative charge, maintaining charge balance and preventing tissue polarization that would occur with conventional stimulation devices.
Data Source
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AI summary
An electrical stimulation system to provide pulse stimulation to an area of a living body by way of one or more electrode leads applied to the area, the area including an associated resistance element and an associated capacitance element. The system may include a pulse generating circuit having a controllable output voltage to generate constant voltage pulses to the one or more electrode leads, wherein the corresponding current signal of each constant voltage pulse includes an exponential decay to a steady state current value. The system may include a controller configured to estimate the associated resistance element of the area, determine a specified target steady state current value to be applied to the area, and control the pulse generating circuit to generate a constant voltage pulse to the one or more electrode leads at a calculated voltage level which achieves the specified target steady state current value to the area.