MEMS Pressure Sensor Nested Pad for Radial Artery Positioning
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Solution Overview
Problem
MEMS pressure sensors have low signal amplitude and high noise levels due to small pressure sensing cavity holes, resulting in a low signal-to-noise ratio, and face challenges in precise positioning over the small radial artery area.
Innovation Solution
The MEMS pressure sensing apparatus includes a pressure sensor unit with a larger space on the pad that communicates with the pressure detection surface, allowing for precise positioning and improved signal quality by creating a sealed space for pressure detection, even when the sensor deviates slightly from the optimal position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the pressure sensing cavity hole diameter is reduced to 1 mm or smaller, then the sensor can be placed on the small radial artery area, but the signal amplitude decreases and noise increases, resulting in low signal-to-noise ratio
Solution Approach 1:
The patent implements a nested structure with multiple spaces: the pressure sensing cavity hole (space 21) is nested within the pressure sensor unit, which is further nested within the pad (space 22). This nested configuration allows the small sensing area to be contained within a larger support structure, maintaining both small footprint and adequate signal quality.
Solution Approach 2:
The patent divides the pressure sensing system into separate functional components: the pressure sensing cavity hole (space 21) for signal detection and the pad (space 22) for support and positioning. This segmentation allows each component to be optimized independently - the sensing cavity remains small for precision while the pad provides a larger stable base.
2Area of stationary object
If the pressure sensing cavity hole diameter is reduced to 1 mm or smaller, then the sensor fits the radial artery area, but the locational range for placement becomes extremely small
Solution Approach 1:
The nested structure allows the small pressure sensing cavity hole to be positioned within the larger pad area, providing a defined placement zone on the radial artery. The pad acts as a positioning platform that guides the sensor to the correct location while the small sensing cavity ensures precise measurement.
Solution Approach 2:
The pad serves as an intermediary component between the pressure sensing cavity hole and the radial artery. It provides a stable interface that facilitates proper positioning and contact, making the placement process more adaptable and easier to perform correctly.
3Ease of operation
If the sensor is placed with slight deviation from optimal position, then placement flexibility increases, but measurement precision decreases with small sensing cavity
Solution Approach 1:
The nested configuration of the pressure sensing cavity hole within the pad creates a hierarchical structure where the smaller sensing element is supported by a larger platform. This allows for some positional variation while maintaining measurement capability, as the pad provides a stable base that accommodates slight placement deviations.
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
This configuration enhances the signal-to-noise ratio and enables precise positioning of the sensor over the radial artery, allowing for reliable and long-term bloodless blood pressure pulse wave measurement without applying pressure.
Implementation Method 1
a diaphragm (2) provided in a center part of the semiconductor substrate (100) and having a pressure detection surface (2a) facing the sealed space (21, 22, 23)
Data Source
Figure 1(a)~1(b)
Figure 2~3A
Figure 3B
AI summary
An MEMS pressure sensing apparatus includes an MEMS pressure sensor, and first and second film sheets. The MEMS pressure sensor has a first space on a side of a pressure detection surface of a diaphragm, has the diaphragm for detecting a pressure using the pressure detection surface facing the first space, and outputs an electrical signal corresponding to the detected pressure. The first film sheet is placed on and in contact with a part under measurement so as to support the MEMS pressure sensor, and has a second space communicating with the first space and having a size in a direction parallel to the pressure detection surface, where the size of the first film sheet being larger than the first space. The second film sheet has a third space with a size in a direction parallel to the pressure detection surface for positioning the MEMS pressure sensing apparatus on the part under measurement, and is placed such that an area of the part under measurement is located in the third space before the MEMS pressure sensing apparatus is placed on the part under measurement.