Optical Contact Pressure Sensor Using Total Internal Reflection
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Solution Overview
Problem
Existing contact pressure measurement methods for living subjects are unreliable due to subject movement during diagnosis, which affects the accuracy of the measured data.
Innovation Solution
An optical contact pressure measuring apparatus that includes a material layer for light path, a spectrum analyzer to detect light absorption, and a pressure calculator to determine contact pressure based on light intensity, utilizing an attenuated total reflectance (ATR) crystalline layer and a light source with an incidence angle greater than the critical angle for total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical measurement methods are used for contact pressure, then the measurement process is simple, but the measurement accuracy deteriorates due to subject movement during diagnosis
Solution Approach 1:
The patent replaces mechanical measurement methods with an optical measurement system. A light source emits light through a material layer to the subject, and a spectrum analyzer detects the reflected light to determine contact pressure based on light absorption characteristics. This substitution eliminates the need for direct mechanical contact and physical sensors on the subject, thereby preventing measurement errors caused by subject movement while maintaining ease of operation.
Solution Approach 2:
The patent changes the measurement parameter from direct mechanical force detection to optical absorption spectrum analysis. By measuring the absorption characteristics of light at different wavelengths and comparing them to reference spectra obtained at known pressure levels, the system indirectly determines contact pressure. This parameter transformation allows accurate measurement without physical contact with the moving subject.
2Measurement precision
If optical measurement methods are implemented, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent employs a spectrum analyzer that serves multiple functions: it analyzes light absorption spectra, compares measured spectra with reference spectra, and calculates contact pressure values. This multi-functional component consolidates what could be multiple separate systems into one device, reducing overall complexity while maintaining high measurement accuracy.
Solution Approach 2:
The patent creates reference absorption spectra at predetermined pressure levels and stores them as reference data. During measurement, the system compares the actual absorption spectrum with these reference copies to determine the contact pressure. This copying approach simplifies the measurement process by avoiding complex real-time calculations and enabling straightforward spectral comparison.
3Reliability
If light absorption spectrum analysis is used, then data reliability increases, but measurement time increases
Solution Approach 1:
The patent performs preliminary measurements to obtain reference absorption spectra at various predetermined contact pressure levels before actual measurements. These reference spectra are stored and used for comparison during subsequent measurements. This preliminary action creates a lookup database that enables rapid determination of contact pressure through simple spectral comparison, reducing measurement time while maintaining high reliability.
Solution Approach 2:
The system uses feedback by comparing the measured absorption spectrum with reference spectra to iteratively determine the contact pressure level. The spectrum analyzer continuously monitors the light absorption characteristics and adjusts the pressure determination based on the degree of spectral matching, enabling reliable and efficient measurement.
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 apparatus provides a reliable and accurate measurement of contact pressure by analyzing light absorption spectra, enhancing data reliability and simplifying the measurement process compared to mechanical methods.
Implementation Method 1
a light source configured to emit the incident light to the material layer with an incidence angle and adjust the incidence angle to be greater than a critical angle to occur total internal reflection
Implementation Method 2
a spectrum analyzer configured to detect light emitted from the material layer and perform a light absorption spectrum analysis on the detected light to determine an intensity of the detected light
Data Source
AI summary
An apparatus and method for measuring a contact pressure and a method of manufacturing the apparatus. The apparatus includes: a material layer configured to provide a light path along which incident light travels to a subject being in contact with the material layer; a spectrum analyzer configured to detect light emitted from the material layer and perform a light absorption spectrum analysis on the detected light to determine an intensity of the detected light; and a pressure calculator configured to determine the contact pressure of the subject based on the determined intensity.