Implantable Microfluidic Pressure Sensor with Optical Telemetry
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Solution Overview
Problem
Current methods for monitoring intracranial pressure in patients with conditions like hydrocephalus require frequent surgeries and radiation-exposing CT scans due to the inability to test shunt functionality post-implantation, leading to unnecessary tests and potential complications.
Innovation Solution
Implantable micro-fluidic pressure sensors with a telemetric measurement system, utilizing a sensing channel and gas chamber to establish a fluid-gas equilibrium interface, allowing for real-time pressure monitoring through bodily tissues, and using IR fluorescent molecules for imaging to quantify pressure levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If implantable pressure sensors with telemetric measurements are used, then the ability to monitor pressure levels in real-time is improved, but the device complexity increases
Solution Approach 1:
The patent extracts the pressure sensing function from complex electronic systems and implements it through a simple microfluidic chamber with a liquid-gas interface. The pressure measurement capability is achieved by observing the position of the liquid meniscus in the channel, eliminating the need for complex electronics while maintaining real-time monitoring capability.
Solution Approach 2:
The patent introduces an optical intermediary (the liquid meniscus) that translates pressure changes into visible position changes. This intermediary allows pressure information to be transmitted through bodily tissues to an external camera without requiring direct electrical or electronic contact, simplifying the implanted device while enabling telemetric measurement.
2Reliability
If frequent surgeries and CT scans are performed to check shunt functionality, then the reliability of pressure monitoring is improved, but the harmful radiation exposure and patient burden increase
Solution Approach 1:
The sensor system enables continuous self-monitoring of pressure levels through the simple act of imaging the liquid-gas interface position. This eliminates the need for external medical interventions like CT scans or repeated surgeries to verify shunt functionality, as the system automatically provides reliability data through routine imaging.
Solution Approach 2:
The patent replaces the mechanical/radiological verification system (CT scans and surgical interventions) with an optical imaging system that uses a smartphone camera or similar device to capture the liquid meniscus position. This substitution eliminates harmful radiation exposure while maintaining reliable pressure monitoring capability.
3Volume of moving object
If the sensing channel inner diameter is reduced to hold fluid through capillary forces, then the device miniaturization is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs capillary forces in a microchannel to hold and position the liquid column without requiring complex retention mechanisms. The capillary action naturally confines the liquid within the channel dimensions, enabling miniaturization while the required precision is achieved through standard micromachining techniques for creating the channel geometry.
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
Reduces the need for unnecessary tests and surgeries by enabling real-time monitoring of pressure levels, decreasing radiation exposure, and providing a direct, linear pressure measurement using a smartphone camera or ultrasound imaging.
Implementation Method 1
the inner diameter of the sensing channel is sized capable of holding the fluid within the sensing channel according to capillary forces
Implementation Method 2
The fluid inside the sensing channel is mixed with IR fluorescent molecules and fluorescence imaging for detection of the gas liquid interface is realized by an IR sensitive camera through a skin tissue
Data Source
AI summary
Continuous pressure sensing is important for patients with several different conditions. We provide an implantable sensor, based on microfluidic principles, which in one example has 1 mmHg limit of detection, high sensitivity and excellent reproducibility. This sensor has an optical interface, which enables pressure to be read with, for example, a cell phone camera. The design and fabrication, along with the option of self-monitoring are promising steps toward better patient care and treatment.