Implantable Pressure Sensor With Wired Transponder Link
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Solution Overview
Problem
Current blood pressure sensing methods for rodents in medical studies using catheters and transponders are inaccurate due to mechanical interference and cause stress, with limited animal lifespan and high maintenance costs.
Innovation Solution
An implantable sensor device with a wired connection between a sensor unit and a transponder unit, utilizing a comparator and digital-to-analogue conversion to enhance signal transmission reliability and reduce circuit size, allowing for accurate and low-energy blood pressure monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a catheter with fluid-filled tube is used to transfer pressure, then pressure can be transmitted to the sensor, but the measurement becomes inaccurate due to mechanical low pass filtering and fluid pillar effects
Solution Approach 1:
The patent extracts and removes the fluid-filled tube from the measurement system, replacing it with a direct mechanical connection between the pressure sensor and the blood vessel. This eliminates the fluid pillar and mechanical low pass filter that were causing measurement inaccuracies and limited signal dynamics.
Solution Approach 2:
The patent replaces the hydraulic transmission system (fluid-filled tube) with a direct mechanical coupling system. The pressure sensor is mechanically coupled to the vessel wall or a balloon element that is directly inflated with blood, eliminating the need for fluid transmission and associated filtering effects.
2Measurement precision
If an external catheter is connected to the animal, then pressure measurement is possible, but the animal experiences massive stress and cannot move freely
Solution Approach 1:
The patent segments the measurement system into an implantable pressure sensor unit that remains inside the animal and an external data acquisition unit. The sensor unit is small enough to be implanted without causing excessive stress, while the external unit handles data processing, eliminating the need for long external catheter connections.
Solution Approach 2:
The patent nests the pressure sensor within a small implantable unit that is inserted into the animal's body cavity or bloodstream. This nested structure allows the sensor to be positioned close to the measurement site while keeping the overall implantable unit compact and minimally invasive.
3Ease of operation
If a transponder with volume of 1 cm3 is implanted, then wireless data transmission is achieved, but the volume occupies space in the small animal and impacts normal anatomy
Solution Approach 1:
The patent extracts the wireless communication and power management functions from the implantable sensor unit and places them in an external data acquisition unit. This allows the implantable unit to be made extremely small (much less than 1 cm3) while still achieving wireless data transmission through the external reader/writer system.
Solution Approach 2:
The external reader/writer unit serves multiple functions: it provides wireless power transmission to the implantable sensor, retrieves measurement data, and communicates with the external system. This multi-functional external unit eliminates the need for a large battery and complex electronics in the implantable unit.
4Ease of operation
If a battery-powered RF transponder is used, then wireless communication is possible, but the lifetime is severely limited and refurbishment is required
Solution Approach 1:
The patent replaces the battery-powered RF transponder with a passive or inductively powered sensor unit. The implantable sensor draws power from an external source through inductive coupling or capacitive coupling when near the external reader/writer, eliminating the need for an internal battery and associated lifetime limitations.
Solution Approach 2:
The implantable sensor unit harvests power during data transmission intervals from the external reader/writer's electromagnetic field. This self-powered operation during measurement intervals eliminates the need for battery replacement or refurbishment, extending the device lifetime to match the animal's lifespan.
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 accurate, low-stress, and long-term blood pressure monitoring for rodents with reduced energy consumption and minimal impact on the animal's anatomy, overcoming the limitations of existing methods.
Implementation Method 1
The sensor unit includes a sensor adapted to sense a characteristic of the body in vivo
Data Source
AI summary
A sensor device includes an implantable sensor unit, a transponder unit, and a wired connection flexibly and electrically connecting the implantable sensor unit and the transponder unit. The implantable sensor unit is adapted to be implanted into a body. The implantable sensor unit includes a comparator and a sensor adapted to sense a characteristic of the body in vivo. The sensor is adapted to supply an analog signal to a first input of the comparator. The transponder unit is adapted to supply a control signal to the implantable sensor unit and to receive an output signal of the comparator. The implantable sensor unit is adapted to supply an analog approximation signal to a second input of the comparator in response to the control signal. The wired connection is adapted to transmit the control signal and the output signal of the comparator.