Implantable Resonant Circuit for Wireless Suture Tension Sensing

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Solution Overview

Problem

Current rehabilitation processes for tendon and ligament injuries rely on qualitative factors like patient pain tolerance, leading to inconsistent and potentially suboptimal healing outcomes due to patient variability, lacking a non-intrusive, patient-specific, and quantitative biofeedback for monitoring suture tension.

Innovation Solution

An implantable sensor with a resonant circuit, comprising an inductor and capacitor, that deforms in response to suture tension, changing its resonant frequency, allowing for wireless detection of suture tension through electromagnetic coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If qualitative factors like patient pain tolerance are used to evaluate rehabilitation progress, then the evaluation process is simple and non-intrusive, but the measurement precision and consistency are poor due to patient variability

Engineering Contradiction:

Improvesuture tension measurement precisionVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical strain gauge systems with a simplified resonant circuit system. The resonant frequency of the circuit directly correlates with suture tension, eliminating the need for complex mechanical transduction while achieving high measurement precision through wireless electromagnetic detection

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from electrical resistance (in strain gauges) to resonant frequency. This parameter change simplifies the overall system while improving measurement precision, as resonant frequency measurements are inherently more accurate and less susceptible to environmental interference

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If traditional strain gauge sensors are used to measure suture tension, then quantitative data can be obtained, but the device complexity and potential for tissue irritation increase

Engineering Contradiction:

Improvesuture tension quantitative measurementVSAvoidtissue irritation from intrusive sensors

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent substitutes mechanical strain gauge sensors that require direct physical contact with tissue with a resonant circuit system that measures tension through electromagnetic resonance. This eliminates intrusive mechanical elements while maintaining quantitative measurement capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an enclosure as an intermediary between the suture and the resonant circuit. The enclosure deforms in response to suture tension and transmits this deformation to the resonant circuit, allowing indirect measurement that avoids direct tissue contact and reduces irritation

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If real-time monitoring of suture tension is implemented, then rehabilitation therapy can be personalized and optimized, but the device complexity and energy consumption increase

Engineering Contradiction:

Improverehabilitation therapy optimization efficiencyVSAvoidsensor energy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic electromagnetic excitation to induce resonance in the circuit only when measurement data is needed. The resonant circuit naturally oscillates at its resonant frequency when excited, allowing for energy-efficient periodic measurements rather than continuous energy consumption

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The resonant circuit is designed to be passively detected by external electromagnetic fields. The circuit itself generates the resonant signal without requiring active power consumption, as the resonance is excited by external fields and the system harvests energy from the measurement process itself

Inventive Principle:

Principle #25Self-service

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

Provides real-time, quantitative data on suture tension, enabling personalized rehabilitation therapy, reducing the risk of reinjury and optimizing healing outcomes by accurately monitoring tissue loading during rehabilitation.

Implementation Method 1

The resonant circuit is configured to electrically resonate at a resonant frequency when exposed to a first electromagnetic field

Methodology Applied

Scientific EffectElectromagnetic resonance: Resonance

Implementation Method 2

The substrate is configured to deform in response to a tensile force applied by the suture and to change a resonant parameter of the resonant circuit in response to the deformation

Methodology Applied

Scientific EffectDeformation: Deformation

Data Source

PatentUS20250387084A1Wireless measurement of suture tension

Publication Date: 2025.12.25 UNIVERSITY OF OREGON

AI summary

Certain examples of the disclosure concern an implantable sensor. The implantable sensor includes a sensor assembly configured to comlect to a suture. The sensor assembly also includes a substrate and a resonant circuit coupled to the substrate. The resonant circuit is configured to electrically resonate at a resonant frequency when exposed to a first electromagnetic field and to emit a second remotely detectable electromagnetic field. The substrate is configured to deform in response to a tensile force applied by the suture and to change a resonant parameter of the resonant circuit in response to the deformation.