Tissue Impedance Measurement Using Pulsed Excitation Feedback

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Solution Overview

Problem

Existing medical treatments often lack real-time, quantitative sensor data for tissue monitoring, particularly in wound care, orthopedic treatments, and internal tissue repair, relying on visual inspection or limited means, which can obscure underlying tissue damage.

Innovation Solution

Incorporation of sensor-enabled substrates into treatment regimes, including garments, cushions, and surgical drapes, to collect and transmit tissue impedance data, utilizing energy harvesting and communication with external devices for improved monitoring and treatment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional electrical cardioversion is used, then cardiac arrhythmia can be treated, but patient movement during the procedure causes measurement errors and reduces treatment accuracy

Engineering Contradiction:
Improveimpedance measurement accuracyVSAvoidpatient movement control
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system applies electrical energy in periodic pulses rather than continuous waves, allowing measurement windows between pulses when tissue impedance is stable. This periodic pulsing enables accurate impedance measurements to be taken during intervals when the patient is less likely to move, resolving the contradiction between measurement precision and ease of operation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system continuously monitors tissue impedance and uses this feedback to adjust the timing and delivery of electrical energy. When impedance changes indicate patient movement, the system can pause energy delivery and retry measurements, maintaining accuracy without requiring the operator to physically restrain the patient.

Inventive Principle:
Principle #23Feedback

2Reliability

If electrical energy is delivered to defibrillate or cardiovert, then cardiac arrhythmia is treated, but tissue heating and burns may occur

Engineering Contradiction:
Improvecardiac arrhythmia treatment efficacyVSAvoidtissue heating and burns
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

By delivering electrical energy in periodic pulses with controlled duty cycles rather than continuous delivery, the system achieves effective cardioversion while allowing tissue to cool between pulses. This reduces cumulative heating and burn risk while maintaining treatment efficacy through repeated sub-threshold stimulations.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system delivers partial energy in multiple smaller pulses rather than one excessive high-energy shock. This distributed energy delivery achieves the same therapeutic effect with lower peak power, reducing tissue heating and burn hazards while maintaining reliability of arrhythmia treatment.

Inventive Principle:
Principle #16Partial or excessive action

3Measurement precision

If impedance measurements are taken continuously, then patient movement can be detected, but energy delivery interruptions reduce treatment efficiency

Engineering Contradiction:
Improvemovement detection accuracyVSAvoidtreatment efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system uses periodic impedance measurements at strategically timed intervals rather than continuous monitoring. Measurements are taken during natural pauses in energy delivery when patient movement is less likely, providing sufficient movement detection accuracy without requiring frequent interruptions that would reduce treatment efficiency.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs preliminary impedance measurements before each energy delivery sequence to establish baseline values. This allows movement detection without interrupting the main treatment protocol, as the baseline is already established and can be used for comparison during continuous monitoring.

Inventive Principle:
Principle #10Preliminary action

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

Enhances real-time monitoring of tissue health, enabling better diagnostic and patient management decisions, and providing continuous data collection for wound healing and surgical precision.

Implementation Method 1

measuring an impedance of the tissue using the impedance data and the model

Methodology Applied
Scientific EffectElectrical Impedance: Electrical Resistance

Data Source

PatentEP3941346B1Systems and methods for measuring tissue impedance
Publication Date: 2026.05.06 SMITH & NEPHEW PLC
  • EP3941346B1 patent drawingFigure 1A~1B
  • EP3941346B1 patent drawingFigure 1C
  • EP3941346B1 patent drawingFigure 1D

AI summary

A system can include excitation pads that can apply an excitation signal to tissue of a patient. The excitation pads can be connected to an electronic circuit that communicates the excitation signal to the excitation pads. The system can include a measurement sensor that can measure voltage of the tissue. The system can include a controller that can determine impedance of the tissue. The controller can be in communication with the excitation pads, the electronic circuit, and the measurement sensor. The controller can generate the excitation signal. The controller can obtain a current measurement of the excitation signal after it has been communicated through at least a portion of the electronic circuit. The current measurement can correspond to the excitation signal before it is applied to the tissue. The controller can determine impedance of the tissue based on the voltage measurement and the current measurement of the excitation signal.