FTIR Optical Pressure Sensor for Miniaturized Force Detection
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Solution Overview
Problem
Existing optical pressure sensors are limited in miniaturization and are primarily designed for measuring pressures on large surfaces, lacking the capability for miniaturized applications.
Innovation Solution
An optical pressure sensor based on frustrated total internal reflection (FTIR) technology, utilizing an optical guide, elastically deformable elements, and photoresistors to detect pressure changes, enabling miniaturization and precise pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical pressure sensors are designed for measuring pressures on large surfaces, then measurement accuracy is improved, but device size and miniaturization capability deteriorate
Solution Approach 1:
The sensor divides the optical guide into multiple segments with different refractive indices along the light propagation path. This segmentation allows the sensor to maintain accurate pressure measurement capability while reducing the overall sensor volume, as each segment contributes differently to the total optical path length and measurement precision.
Solution Approach 2:
The patent transitions from measuring pressure over large surface areas to measuring pressure along the length of the optical guide. By utilizing the longitudinal dimension of the optical guide rather than relying on large transverse measurement areas, the sensor achieves accurate pressure measurement in a compact form factor.
2Volume of moving object
If optical pressure sensors are miniaturized, then device compactness is improved, but versatility for different applications deteriorates
Solution Approach 1:
The sensor design with multiple optical guide segments having different refractive indices creates a universal measurement platform that can adapt to various pressure measurement applications. The segmented structure allows the same compact sensor to be configured for different measurement ranges and applications by adjusting the refractive index distribution along the optical path.
Solution Approach 2:
By varying the refractive indices of different optical guide segments, the sensor can adjust its measurement characteristics to suit different applications. This parameter change approach allows a single compact sensor design to serve multiple purposes, from low-pressure to high-pressure measurements, enhancing versatility without increasing size.
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 sensor allows for miniaturized pressure detection, providing accurate and real-time data on pressure, force, and direction without interfering with user experience, and can distinguish between intentional and unintentional hand actions.
Implementation Method 1
an optical guide 2, rigid and transparent, having a critical angle and configured to generate an output optical radiation along an optical path from an input optical radiation supplied to the optical guide 2 through a total internal reflection at an outer wall of the optical guide 2
Implementation Method 2
at least one load cell 11... in contact with said outer wall 7... configured to modify a contact area with said outer wall 7... through a frustrated total internal reflection
Data Source
AI summary
An optical pressure sensor including an optical radiation source and an optical guide that may be optically coupled to the radiation source and may be configured to obtain a total internal reflection condition. The optical guide may define an interface wall. The sensor may also include an element elastically deformable and transparent to optical radiation that has a face facing said interface wall and configured so that a pressure exerted on the deformable element changes a contact area with the interface wall so that the optical guide assumes a frustrated total internal reflection condition with emission of an output optical radiation towards the first face of the deformable element dependent on the exerted pressure. The sensor may further include a photoresistor optically coupled to the second face of the deformable element and configured to provide an electrical signal dependent on the output optical radiation.