Implantable Strain Sensor with Inductive Power
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Solution Overview
Problem
Current methods for monitoring spinal fusion after lumbar surgery are inefficient, requiring prolonged use of spinal braces due to reliance on radiographic verification, which can be delayed, and lack effective means for monitoring strain in other medical conditions.
Innovation Solution
A system incorporating an implantable inter-digitated capacitor-based strain sensor with RF signal transmission and inductive power supply, allowing for miniaturized strain sensing and data collection without internal batteries, enabling early detection of spinal fusion and monitoring of other medical conditions like glucose levels and heart rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radiographic verification is used to monitor spinal fusion, then fusion progress can be detected, but the monitoring is delayed and requires prolonged brace usage
Solution Approach 1:
The patent replaces the mechanical/radiographic verification system with an electrical sensing system. Strain sensors attached to the spinal instrumentation continuously measure strain levels, providing real-time feedback on fusion progress without requiring delayed radiographic imaging. This substitution enables earlier and more accurate detection of fusion milestones.
Solution Approach 2:
The strain sensing system provides self-monitoring capability that continuously tracks fusion progress without external intervention. The system automatically detects when fusion milestones are achieved through continuous strain measurement, eliminating the need for periodic radiographic checks and enabling timely brace removal.
2Measurement precision
If traditional strain monitoring methods are used, then strain measurement is possible, but the devices are too large for implantation and require internal batteries
Solution Approach 1:
The patent extracts the power supply function from the implantable sensor itself and relocates it to an external source. The implantable strain sensors are designed without internal batteries, instead receiving power inductively from an external coil positioned over the implant site. This extraction eliminates the size and complexity constraints imposed by internal power sources.
Solution Approach 2:
The patent introduces an inductive coupling mechanism as an intermediary between the external power source and the implantable sensors. The external coil acts as a mediator that wirelessly transfers energy to the implant through electromagnetic induction, enabling power delivery without physical connections or internal batteries.
3Stability of the object's composition
If prolonged immobilization with braces is used after lumbar fusion, then spinal stability is maintained, but muscle atrophy and stress shielding occur
Solution Approach 1:
The patent implements a feedback system where strain sensor data is continuously monitored and used to determine when fusion milestones are achieved. This feedback enables dynamic adjustment of brace removal timing based on actual fusion progress rather than fixed schedules, allowing earlier brace removal when fusion is confirmed while maintaining stability when needed.
Solution Approach 2:
The patent transitions from a static, fixed-duration brace protocol to a dynamic, adaptive protocol. The brace wear duration is adjusted based on real-time strain measurement feedback, enabling the treatment regimen to evolve as fusion progresses. This dynamic approach optimizes the balance between maintaining stability and preventing harmful effects of prolonged immobilization.
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
Enables rapid detection of spinal fusion, reducing brace duration by up to 50% and facilitating monitoring of various medical conditions through accurate strain measurement and data transmission, improving patient recovery and outcome.
Implementation Method 1
The sensor comprises an inter-digitated capacitor
Implementation Method 2
The system includes an inductively coupled power supply
Data Source
AI summary
A system for monitoring strain as an indicator of biological conditions, such as spinal fusion, glucose levels, spinal loading, and heart rate. The system includes an inter-digitated capacitor sensor, and RF transmitter, and an associated antenna, all of which are microminiature or microscopic in size and can be implanted in a biological host such as a human or animal. An inductively coupled power supply is also employed to avoid the need for implantation of chemical batteries. Power is provided to the sensor and transmitter, and data is transmitted from the sensor, when an external receiving device, such as a handheld RF ID type receiver, is placed proximate the location of the implanted sensor, transmitter and inductively coupled power supply. The implanted sensor, transmitter and inductively coupled power supply can be left in place permanently or removed when desired.