Nerve Stimulator Detection Circuit Open Circuit and Current Monitoring
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Solution Overview
Problem
In implantable nerve stimulators, if one or more stimulation branches become disconnected, the current in other branches increases, potentially causing tissue damage due to excessive current flow, necessitating a detection circuit to monitor connection and current distribution.
Innovation Solution
A detection circuit for nerve stimulators that includes an open circuit detection branch with a comparator and digital logic, and a current detection branch with an amplifier and switch, integrated with a sampling resistor to detect both open circuits and current levels, using a single operational amplifier for both functions and incorporating offset voltage calibration and gain adjustment to ensure accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a detection circuit is added to monitor stimulation branches, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The patent combines open circuit detection and current level detection functions into a single integrated detection circuit. The operational amplifier serves dual purposes: detecting open circuits through voltage comparison and measuring current levels through voltage division. This merging approach maintains high reliability while reducing device complexity by eliminating the need for separate detection circuits for each function.
Solution Approach 2:
The detection circuit is designed with multi-functionality, where the same circuit components perform multiple detection tasks. The operational amplifier can operate in different modes (comparator mode and amplification mode) to detect both open circuits and current levels. This universal design improves safety coverage without proportionally increasing circuit complexity.
2Measurement precision
If separate detection circuits are used for open circuit detection and current detection, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs dynamic switching between different detection modes within the same circuit. The operational amplifier can dynamically change its operating state based on the detection requirements - acting as a comparator for open circuit detection and as an amplifier for current level detection. This dynamic capability allows the circuit to maintain high measurement precision for both functions while avoiding the complexity of having permanently separate dedicated circuits for each detection type.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The detection circuit effectively identifies open circuits and abnormal current levels, allowing for user adjustments to prevent tissue damage from excessive current, enhancing safety and accuracy by integrating open circuit and current detection with calibration and gain management.
Implementation Method 1
A positive input terminal of the comparator U1 is connected to one end of the sampling resistor Rs adjacent to the stimulation source VDDH, a negative input terminal of the comparator U1 is connected to one end of the sampling resistor Rs facing away from the stimulation source VDDH
Implementation Method 2
The current detection branch includes an amplifier U1 and a first switch S1. A negative input terminal of the amplifier U1 is connected to the one end of the sampling resistor Rs facing away from the stimulation source VDDH
Implementation Method 3
incorporating offset voltage calibration and gain adjustment to ensure accurate detection
Implementation Method 4
A negative input terminal of the amplifier U1 is connected to the one end of the sampling resistor Rs facing away from the stimulation source VDDH, and an output terminal of the amplifier U1 is connected to a control terminal of the first switch S1
Data Source
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AI summary
Provided is a detection circuit for a nerve stimulator. The nerve stimulator includes a stimulation source (VDDH) and a stimulation branch communicated with the stimulation source (VDDH). A sampling resistor (Rs) is disposed in the stimulation branch. The detection circuit includes an open circuit detection branch and a current detection branch. The open circuit detection branch includes a comparator (U1) and a digital logic branch (DI). A positive input terminal of the comparator (U1) is connected to one end of the sampling resistor (Rs) adjacent to the stimulation source (VDDH), a negative input terminal of the comparator (U1) is connected to one end of the sampling resistor (Rs) facing away from the stimulation source (VDDH), and an output terminal of the comparator (U1) is connected to the digital logic branch (DI). The current detection branch includes an amplifier (U1) and a first switch (S1). A negative input terminal of the amplifier (U1) is connected to the one end of the sampling resistor (Rs) facing away from the stimulation source (VDDH), an output terminal of the amplifier (U1) is connected to a control terminal of the first switch (S1), two connection terminals of the first switch (S1) are connected to a first resistor (R1) and a second resistor (R2), respectively, another end of the first resistor (R1) is connected to the stimulation source (VDDH), another end of the second resistor (R2) is grounded, and a positive input terminal of the amplifier (U1) is connected to one end of the first resistor (R1) adjacent to the first switch (S1).