Implantable Strain Sensor Using Passive RFID and Capacitor Timing
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Solution Overview
Problem
Conventional implantable sensors require high power consumption, necessitating large batteries that are not biocompatible and hinder miniaturization, while achieving sufficient sensitivity and accuracy.
Innovation Solution
Implantable sensors with low power needs, utilizing energy harvesting techniques and passive wireless communication, incorporating strain gauges with semiconductor elements and capacitors to measure anatomical properties, and transmitting data wirelessly through the skin using RFID technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional implantable sensors use large batteries to provide sufficient power, then power consumption requirements are met, but biocompatibility is compromised and device size increases
Solution Approach 1:
The patent removes the battery component entirely from the implantable sensor system. Instead of using conventional battery-powered operation, the sensor utilizes energy harvesting from the body's natural electromagnetic fields and thermal gradients, extracting power from the environment rather than carrying an onboard power source. This extraction principle directly resolves the contradiction by eliminating the biocompatibility issue associated with large batteries while maintaining operational power requirements.
Solution Approach 2:
The sensor system serves itself by harvesting energy from the patient's body through thermoelectric generators that convert body heat into electrical power. The system is self-powered without external battery replacement or recharging, using the body's own thermal energy as the power source. This self-service approach eliminates the need for biocompatible battery containment while ensuring continuous operation.
2Use of energy by moving object
If conventional implantable sensors use large batteries, then sufficient power is available, but device miniaturization is hindered
Solution Approach 1:
The battery is extracted from the device architecture, replacing it with distributed energy harvesting elements that generate power in-situ. Thermoelectric generators and electromagnetic induction coils are integrated directly into the sensor structure, eliminating the need for a separate battery compartment and enabling significant miniaturization of the implantable device.
Solution Approach 2:
The power generation function is merged with the sensing function in a unified integrated structure. The strain gauge elements serve dual purposes as both mechanical sensors and components of the energy harvesting circuitry, eliminating separate power supply components and reducing overall device volume.
3Use of energy by moving object
If passive wireless communication is used, then power consumption is reduced, but communication range and reliability may be limited
Solution Approach 1:
The patent replaces active electronic communication transmitters with passive electromagnetic coupling mechanisms. Instead of using powered radio frequency transmitters that consume battery energy, the system uses inductive coupling between an external reader coil and an internal sensor coil to transfer both power and data, eliminating the need for active transmission while enabling communication through the skin.
Solution Approach 2:
The skin and tissue between the implant and external reader serve as the communication medium rather than requiring direct line-of-sight or high-power transmission. The electromagnetic fields penetrate the tissue to establish communication, using the body itself as the intermediary channel for passive data transfer.
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 solution enables accurate, miniaturized sensors that can track health parameters with low power consumption, using energy harvesting and passive RFID, suitable for implantation without large batteries, and providing reliable health monitoring.
Implementation Method 1
The measurement device includes at least one capacitor. The measurement device is configured to measure a discharge time of the at least one capacitor through the resistor
Implementation Method 2
The at least one sensing element includes a resistor. The measurement device is configured to measure a discharge time of the at least one capacitor through the resistor
Implementation Method 3
The wireless communicator is configured to wirelessly communicate the measurement value through skin of the patient to an external wireless communicator situated outside of the patient's body
Data Source
AI summary
In one example, a sensor is configured to be implanted into a patient's body. The sensor has at least one sensing element, a measurement device in communication with the at least one sensing element, and an internal wireless communicator in communication with the measurement device. The at least one sensing element includes a resistor, and the measurement device includes a capacitor. The measurement device measures a discharge time of the capacitor through the resistor so as to generate a measurement value that is proportional to a value of an anatomical property of the anatomical body, such as strain, that is observed by the sensor. The internal wireless communicator wirelessly communicates the measurement value through skin of the patient to an external wireless communicator situated outside of the patient's body.