Implantable Joint Sensor Capsule With Wireless Charging
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Solution Overview
Problem
Existing implantable devices for monitoring joint environments are complex, expensive, and impractical, requiring additional bone and soft tissue removal, and external tracking devices are cumbersome and provide inaccurate information.
Innovation Solution
An implantable device with a sensor module, communications unit, and rechargeable battery encapsulated in a capsule, which can be releasably mounted within a joint body to monitor mechanical, chemical, and biological properties in real-time, and is powered wirelessly using a charging module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If instrumented implants are used to monitor joint environment, then measurement precision is improved, but device complexity increases and additional bone/soft tissue removal is required
Solution Approach 1:
The implantable device is segmented into three main functional modules: sensor module (with strain gauges, temperature sensor, motion sensor), power supply (rechargeable battery), and communications unit. These modules are contained within a capsule that is releasably mounted within the joint body, allowing independent development and testing of each module while reducing overall system complexity
Solution Approach 2:
The sensor module, power supply, and communications unit are nested within a capsule structure. The capsule itself is mounted within an opening of the joint body (such as within a prosthetic joint component or bone). This nested arrangement consolidates multiple functions into a compact package that fits within existing anatomical or prosthetic spaces without requiring additional bone removal
2Measurement precision
If instrumented implants with larger size are used, then measurement precision is improved, but the implant requires additional bone and soft tissue removal
Solution Approach 1:
The capsule containing the sensor module is designed with a flexible or thin-walled structure that can be releasably mounted within the joint opening. This allows the sensor module to maintain close contact with the joint environment for accurate measurement while occupying minimal volume. The flexible capsule can conform to the available space within the joint body or prosthetic component
Solution Approach 2:
The sensor module is positioned at specific locations within the joint where critical measurements can be obtained (such as near articulating surfaces for wear detection or in synovial fluid for chemical analysis). This localized sensing approach provides high measurement precision without requiring the entire implant to be enlarged, thus avoiding additional bone removal
3Ease of operation
If external tracking devices are used to monitor patient progress, then ease of operation is improved, but measurement precision deteriorates due to improper placement and patient compliance issues
Solution Approach 1:
The implantable device performs self-monitoring of the joint environment without requiring patient action. The sensor module continuously measures parameters such as strain, temperature, motion, and chemical composition automatically. The communications unit autonomously transmits data to external devices, eliminating the need for patients to manually operate or remember to use external tracking devices
Solution Approach 2:
The implantable device acts as an intermediary between the joint environment and external monitoring systems. Instead of relying on external devices that require proper placement and patient compliance, the sensing function is transferred to an internal device that is always present in the joint. This intermediary approach ensures continuous, accurate data collection while maintaining ease of external data retrieval through wireless communications
4Measurement precision
If implantable device with continuous monitoring is used, then measurement precision is improved, but use of energy increases requiring larger battery
Solution Approach 1:
The sensor module and communications unit are designed to operate in periodic cycles rather than continuously. The sensor module continuously monitors joint parameters, but data transmission occurs periodically or event-driven (e.g., when threshold values are exceeded or at scheduled intervals). This periodic operation maintains measurement precision while significantly reducing average power consumption of the communications unit, which is typically the highest energy consumer
Solution Approach 2:
The device includes a rechargeable battery with optimized capacity and voltage characteristics suitable for low-power operation. The power management system dynamically adjusts operating parameters such as sampling frequency, transmission power, and sleep mode duration based on battery charge level and monitoring requirements. This parameter adaptation allows continuous monitoring capability while extending battery life and reducing the physical size of the power supply
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 continuous, accurate monitoring of joint environments, reducing hospital visits, improving patient recovery, and early detection of implant issues, while maintaining the joint's functionality and simplifying manufacturing and regulatory processes.
Implementation Method 1
a charging module for powering an implantable device... a charging coil configured to generate a magnetic field for wirelessly transferring power to the rechargeable battery
Implementation Method 2
a charging coil configured to generate a magnetic field for wirelessly transferring power to the rechargeable battery
Data Source
AI summary
An implantable device for monitoring an intra-articular joint environment corresponding to a joint body, for example a bone or a prosthetic joint component. The implantable device comprises: a sensor module configured to measure data indicative of at least one parameter of an intra-articular joint environment corresponding to a joint body; a communications unit operatively coupled to the sensor module and configured to transmit the measured data to an external device; and a rechargeable battery configured to power the sensor module and the communications unit, wherein the sensor module, the power supply and the communications unit are contained within a capsule, wherein the capsule is releasably mountable within an opening of the joint body, and wherein, when the capsule is releasably mounted within the opening of the joint body, the sensor module is configured to monitor the at least one parameter of the intra-articular joint environment.