SCR-Based Defibrillation Pulse Protector for Wearable ECG

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Solution Overview

Problem

Existing defibrillator pulse protection systems, such as those using Argon or Neon bulbs, are bulky and have high ON voltage, making them unsuitable for compact, flexible form factors in modern wearable medical devices, and require additional protection circuits due to their high voltage limits exceeding the capabilities of low-voltage ECG monitoring equipment.

Innovation Solution

A silicon-controlled rectifier (SCR)-based clamp with a low resistance and high current-capability is used to shunt away excessive defibrillation pulse energy, providing dual-direction voltage tolerance protection and intrinsic triggering, eliminating the need for external triggering circuits and secondary protection stages, and incorporating metal layers for heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gas discharge tubes (Argon or Neon bulbs) are used for defibrillator pulse protection, then voltage limiting function is achieved, but the device becomes bulky and has high ON voltage

Engineering Contradiction:

Improvevoltage limiting functionVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent changes the fundamental parameters of the protection device by transitioning from gas discharge tubes to an SCR-based circuit. This enables the device to achieve low ON voltage (approximately 2V at 100mA) and low resistance (around 1Ω) while maintaining compact dimensions suitable for modern wearable medical devices.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the gas discharge tube mechanism with an electronic SCR-based protection circuit. This substitution eliminates the need for bulky gas-filled tubes and secondary protective networks, achieving both compact size and low voltage operation through solid-state electronics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If gas discharge tubes are used for defibrillator pulse protection, then voltage limiting is provided, but high ON voltage requires a second protective network

Engineering Contradiction:

Improvevoltage limiting functionVSAvoidprotection circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The SCR-based protection circuit is self-triggering, automatically activating when exposed to high voltage defibrillation pulses. The intrinsic triggering mechanism eliminates the need for external triggering circuits or secondary protective networks, simplifying the overall device architecture while maintaining effective protection.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts and eliminates the secondary protective network that was previously required when using gas discharge tubes. The SCR-based circuit provides both voltage limiting and current shunting functions in a single integrated device, removing the need for additional protective components.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If gas discharge tubes are used for defibrillator pulse protection, then voltage protection is achieved, but the bulky form factor makes packaging difficult

Engineering Contradiction:

Improvevoltage protectionVSAvoiddevice thickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent transforms the physical parameters of the protection device by using an SCR-based circuit instead of gas discharge tubes. This enables the device to achieve thin, flexible form factors suitable for modern wearable medical devices while maintaining effective voltage protection capabilities.

Inventive Principle:

Principle #35Parameter changes

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 SCR-based clamp effectively limits voltage to safe levels for ECG monitoring equipment during defibrillation, ensuring protection without the bulkiness and high ON voltage of traditional solutions, and can be applied in various microelectronic industries beyond defibrillator pulse protection.

Implementation Method 1

The basic SCR intrinsically triggers when a voltage of about 10.5 V is applied across its terminals (or electrodes), and then goes into a low voltage state (around 2 V at 100 mA) with an on-state resistance of around 1Ω

Methodology Applied

Scientific EffectSilicon-controlled rectifier (SCR) triggering and latching:

Implementation Method 2

stack of metal layers may be used to provide high current and heat-sink capability with each electrode metal layer fully filled with VIAs

Methodology Applied

Scientific EffectHeat dissipation through metal layers: Heat Sink

Data Source

PatentUS9948091B1Integrated defibrillation pulse protector

Publication Date: 2018.04.17 MAXIM INTEGRATED PROD INC

AI summary

Silicon-controlled rectifier (SCR) based circuit for ECG protection under defibrillator pulse is disclosed. The SCR-based clamp is a symmetric structure for dual-direction voltage tolerance protection based on two anti-series P-well/N-well lateral blocking junctions isolated from P-substrate by the N-buried layer. The injector regions (n+/p+) are substantially lengthened in order to accommodate a larger number of contact rows than typically used for ESD pulses specification. A stack of metal layers may also be used to provide high current and heat-sink capability with each electrode metal layer fully filled with VIAs.