Modulated Physiological Sensor for Variable Skin Coupling
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Solution Overview
Problem
Existing physiological sensors face challenges in achieving optimal coupling with the skin surface, leading to inefficient detection of physiological signals due to variations in skin characteristics, particularly in terms of shape, texture, and elasticity, which affects signal amplitude and frequency detection.
Innovation Solution
A modulated physiological sensor system that utilizes a modulator, such as a vibration element, to vary the coupling of detectors to the skin surface, ensuring maximal and minimal coupling during each modulation cycle, with modulation frequencies set above detector low-frequency cutoffs, thereby amplifying detector signals using AM demodulation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a physiological sensor is applied to the skin surface to detect physiological signals, then physiological parameters can be measured, but the detection efficiency is reduced due to variations in skin characteristics (shape, texture, elasticity) that affect signal coupling
Solution Approach 1:
The patent applies a vibration element that dynamically modulates the coupling between the detector and skin surface at a specific frequency (e.g., 120 Hz). This dynamic modulation overcomes the static coupling variations caused by skin characteristics, allowing the detector to maintain optimal signal reception despite changes in skin shape, texture, or elasticity. The vibration creates periodic contact variations that amplify the physiological signal detection while filtering out noise from inconsistent coupling.
2Measurement precision
If the detector is directly coupled to the skin surface, then physiological signals can be detected, but low-frequency and low-amplitude signals are difficult to distinguish from noise
Solution Approach 1:
The patent employs a vibration element that mechanically oscillates the detector-skin interface at a predetermined frequency (e.g., 120 Hz). This mechanical vibration modulates the physiological signals (such as respiration-induced skin movements) onto a higher frequency carrier, effectively shifting them away from the low-frequency noise region. The modulation frequency is specifically chosen to be above the typical range of physiological noise, enabling easier signal extraction through demodulation techniques.
Solution Approach 2:
The vibration element applies periodic mechanical oscillations to the detector-skin coupling at a consistent frequency. This periodic action creates a modulated signal envelope that corresponds to the physiological parameters of interest. By using periodic modulation rather than continuous coupling, the system can distinguish between the modulated physiological signals and random noise through frequency-domain analysis or envelope detection, significantly improving signal-to-noise ratio.
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 system effectively amplifies low-amplitude and low-frequency physiological signals, enhancing the detection and measurement of parameters like respiration rate and blood composition by optimizing the detector-skin interface through dynamic coupling modulation.
Implementation Method 1
A modulated physiological sensor has a detector that communicates with a surface area of a living being so as to generate a signal responsive to a physiological reaction of the living being to the perturbation. A modulator varies the coupling of the detector to the surface area so as to at least intermittently maximize the detector signal.
Implementation Method 2
An acoustic sensor utilizing a piezoelectric device attached to the neck is capable of detecting these sound waves and outputting a modulated sound wave envelope that can be demodulated so as to derive respiration rate.
Data Source
AI summary
A modulated physiological sensor is a noninvasive device responsive to a physiological reaction of a living being to an internal or external perturbation that propagates to a skin surface area. The modulated physiological sensor has a detector configured to generate a signal responsive to the physiological reaction. A modulator varies the coupling of the detector to the skin so as to at least intermittently maximize the detector signal. A monitor controls the modulator and receives an effectively amplified detector signal, which is processed to calculate a physiological parameter indicative of the physiological reaction.