Capacitive Pressure Sensor for Mouse Eye IOP Monitoring
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Solution Overview
Problem
Current pressure sensors for monitoring intraocular pressure (IOP) are not suitable for mouse eyes due to their size and lack of sensitivity, and existing implantable devices face challenges with power sourcing, including battery replacement and alignment requirements for inductive coupling.
Innovation Solution
A capacitive pressure sensor with a flexible substrate and membrane design that can conform to curved surfaces, integrated with a wireless telemetry system for remote monitoring, and powered by wireless RF signals, allowing for continuous and sensitive IOP measurement within the small anterior chamber of a mouse eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current pressure sensors are used for monitoring intraocular pressure, then measurement capability is provided, but the sensor size is too large to fit within the mouse eye anterior chamber
Solution Approach 1:
The sensor is divided into separate functional layers (sensing element, flexible substrate, encapsulation layers) that can be independently optimized and assembled, enabling miniaturization while maintaining measurement capability
Solution Approach 2:
The sensor incorporates flexible substrates and thin film structures that reduce overall sensor thickness and allow conformal mounting on curved surfaces within the limited space of the mouse eye anterior chamber
2Measurement precision
If current pressure sensors are used for monitoring intraocular pressure, then measurement capability is provided, but the sensitivity is insufficient for detecting small pressure changes in mouse eyes
Solution Approach 1:
The sensing element is designed with optimized local properties including specific diaphragm thickness and electrode configuration in the active sensing region to maximize sensitivity to small pressure changes while keeping overall sensor size small
Solution Approach 2:
The sensor utilizes changes in capacitance parameters in response to pressure-induced diaphragm deflection, providing high sensitivity for detecting small pressure variations in the mouse eye environment
3Duration of action of moving object
If implantable pressure sensors are used for continuous monitoring, then continuous data collection is achieved, but power sourcing becomes problematic due to battery replacement requirements
Solution Approach 1:
The battery is extracted from the implantable sensor system, replacing it with a wireless power transfer mechanism that delivers power through the skin without requiring implanted power sources or surgical battery replacements
Solution Approach 2:
An external power transmission device serves as an intermediary, wirelessly transferring electrical energy to the implanted sensor through electromagnetic coupling, eliminating the need for internal batteries and their associated replacement complexities
4Use of energy by moving object
If inductive coupling is used for wireless power transfer, then power delivery is achieved, but precise alignment between transmitter and receiver is required
Solution Approach 1:
The magnetic coupling system is designed with dynamic characteristics that allow for self-alignment and tolerance of positional variations, reducing the need for precise manual alignment during operation
Solution Approach 2:
The magnetic coupling design incorporates features that counteract misalignment effects, such as distributed winding patterns or magnetic shielding that maintain coupling efficiency across a range of positions
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 provides a compact, sensitive, and continuously monitoring capacitive pressure sensor system that fits within the mouse eye, offering reliable IOP data and eliminating the need for frequent battery replacements or precise alignment, enhancing glaucoma research and other implantable device applications.
Implementation Method 1
a capacitive pressure sensor with a flexible substrate and membrane design that can conform to curved surfaces
Implementation Method 2
powered by wireless RF signals, allowing for continuous and sensitive IOP measurement
Data Source
AI summary
Certain pressure sensor devices are much smaller than prior art devices, yet are at least as sensitive as the prior art devices. A capacitive pressure sensor can include a flexible substrate that permits bending of a pressure sensing region without significantly affecting operation thereof. The pressure sensor can include a flexible membrane in which an electrode is sandwiched between two layers of polymeric material. The sandwiched electrode can be extremely close to a reference electrode so as to provide for highly sensitive capacitance readings, yet the membrane can be restricted from contacting the reference electrode under high pressure conditions.