Self-Injection-Locked Radar Sensor for Vital Sign Detection
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Solution Overview
Problem
Conventional wearable vital sign sensors are limited by sensitivity to environmental light, require firm adhesion to the skin, and have complex, costly structures that hinder miniaturization and versatility, leading to discomfort and reduced measurement accuracy due to body vibrations.
Innovation Solution
A non-contact phase-locked and self-injection-locked vital sign sensor utilizing a self-oscillating voltage-controlled frequency-adjustable radiating element and a phase-locked loop for transmitting and receiving oscillation signals, allowing for frequency tuning and stabilization, and incorporating a base-band amplifier, analog-to-digital converter, and signal-processing device for enhanced sensitivity and reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoelectric sensing method is used, then vital signals can be detected, but sensitivity to environmental light causes measurement errors
Solution Approach 1:
The patent replaces the photoelectric sensing method with a radar-based electromagnetic wave sensing system. The radar sensor transmits electromagnetic waves that reflect off the body surface, and motion detection is achieved through phase modulation of these reflected waves. This substitution eliminates sensitivity to environmental light while maintaining vital signal detection capability through non-contact electromagnetic interaction.
2Measurement precision
If sensor is firmly adhered to skin, then accurate vital signals can be obtained, but long-term usage causes user discomfort
Solution Approach 1:
The patent extracts the sensor from direct contact with the skin by implementing a non-contact radar measurement system. The electromagnetic waves penetrate through air space to detect body surface motion, eliminating the need for adhesive attachment. This allows accurate vital signal acquisition while ensuring user comfort during long-term wear.
3Measurement precision
If two antennas and oscillator are used for non-contact sensing, then vital signs can be detected, but device complexity and cost increase
Solution Approach 1:
The patent merges the transmitting and receiving antenna functions into a single integrated radar sensor element. The single antenna simultaneously transmits electromagnetic waves and receives reflected signals, eliminating the need for separate transmitting and receiving antennas. This integration significantly reduces device complexity and cost while maintaining non-contact vital sign detection capability.
4Ease of operation
If delay line and frequency discriminator are used, then demodulation can be achieved, but occupation space and cost increase
Solution Approach 1:
The patent replaces traditional analog demodulation components (delay line and frequency discriminator) with a digital signal processing approach. The phase-modulated reflected signals are processed through digital algorithms that extract vital sign information, eliminating the need for bulky analog circuitry. This substitution reduces occupation space while maintaining demodulation functionality.
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 high measurement sensitivity, reduced noise, and adjustable frequency stabilization, enabling accurate detection of vital signs like heartbeats and breathing without the need for firm adhesion, while minimizing size and cost.
Implementation Method 1
a self-oscillating voltage-controlled frequency-adjustable radiating element, used for transmitting an oscillation signal to an organism and for receiving a corresponding reflected signal from the organism to be posed at a self-injection-locked state
Implementation Method 2
The oscillation signal is tuned by a vital sign of the organism to form a frequency-tuned signal
Implementation Method 3
a phase-locked loop, used for demodulating the frequency-tuned signal to obtain a corresponding vital signal of the organism; wherein, by comparing the oscillation signal frequency-divided and outputted from the self-oscillating voltage-controlled frequency-adjustable radiating element with a reference signal, a corresponding comparison result is used to vary a phase of the frequency-divided oscillation signal for maintaining the same phase of the reference signal
Data Source
AI summary
A non-contact phase-locked and self-injection-locked vital sign sensor includes a self-oscillating voltage-controlled frequency-adjustable radiating element and a phase-locked loop. The self-oscillating voltage-controlled frequency-adjustable radiating element is used for transmitting an oscillation signal to an organism and for receiving a corresponding reflected signal from the organism to be posed at a self-injection-locked state, the oscillation signal being tuned by a vital sign of the organism to form a frequency-tuned signal. The phase-locked loop is used for demodulating the frequency-tuned signal to obtain a corresponding vital signal of the organism. By comparing the oscillation signal frequency-eliminated and outputted from the self-oscillating voltage-controlled frequency-adjustable radiating element with a reference signal, a corresponding comparison result is used to vary a phase of the frequency-divided oscillation signal for maintaining the same phase of the reference signal. Thereupon, the oscillation frequency can be stabilized, and the measurement sensitivity can be enhanced.