Wearable Bioimpedance Sensor Signal Processing Circuit
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Solution Overview
Problem
Existing bioimpedance sensors face challenges in being truly wearable due to high power consumption and lack of broadband flexibility, making them unsuitable for long-term, non-invasive monitoring of biological characteristics.
Innovation Solution
A low-power, wearable bioimpedance sensor with a signal processing circuit that undersamples a detected voltage response signal, downshifts the carrier frequency to an intermediate frequency, and uses a bandpass filter with a fixed passband, enabling continuous monitoring of biological characteristics like heart rate and blood pressure without the need for frequent recharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional bioimpedance sensors use high-power signal processing circuits, then measurement precision is improved, but power consumption increases making them unsuitable for long-term wearable use
Solution Approach 1:
The patent implements periodic sampling of the bioimpedance signal at specific intervals rather than continuous monitoring. The sampler captures voltage responses at predetermined time points, reducing overall power consumption while maintaining sufficient measurement precision for detecting physiological changes over time.
Solution Approach 2:
The patent extracts only the essential information from the bioimpedance signal by sampling at specific intervals and frequencies, rather than processing the entire continuous signal. This extraction approach maintains measurement precision for detecting physiological changes while significantly reducing power consumption.
2Adaptability or versatility
If traditional bioimpedance sensors use fixed-frequency circuits, then device complexity is reduced, but adaptability to different biological characteristics decreases
Solution Approach 1:
The patent implements dynamic frequency selection where the excitation signal frequency can be varied to match different physiological parameters of interest. The system can adapt the carrier frequency and sampling frequency based on the specific biological characteristic being measured, providing broadband flexibility without requiring completely separate circuits for each measurement type.
Solution Approach 2:
The patent designs a universal signal processing circuit that can measure multiple different biological characteristics (impedance, blood pressure, heart rate, respiration rate) using the same basic hardware components. By programmably adjusting frequencies and sampling rates, a single device performs multiple functions that would traditionally require separate specialized circuits.
3Reliability
If traditional bioimpedance sensors continuously monitor biological characteristics, then reliability of health monitoring is improved, but power consumption increases requiring frequent recharging
Solution Approach 1:
The patent implements periodic monitoring where the sampler captures voltage responses at predetermined time intervals rather than continuously. This periodic sampling maintains reliability for detecting physiological changes and trends over time while dramatically reducing power consumption to enable long-term wearable use without frequent recharging.
Solution Approach 2:
The patent maintains continuous useful monitoring capability through periodic sampling that captures sufficient data points to track physiological changes over time. The system provides continuous health monitoring reliability by accumulating measurements across multiple sampling intervals, ensuring no critical changes are missed while consuming minimal power.
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
Enables continuous, long-term, non-invasive monitoring of biological characteristics with low power consumption and broadband flexibility, allowing for accurate and reliable measurements of cardiovascular traits and other health indicators.
Implementation Method 1
a mixer operable to mix the amplitude-modulated signal with a mixing signal having a mixing frequency to provide a frequency-downshifted signal having an intermediate frequency less than the carrier frequency
Implementation Method 2
a filter operable to filter the frequency-downshifted signal to provide a filtered signal
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
This disclosure provides systems, methods and apparatus for performing signal processing in impedance sensing applications, and more specifically, for recovering data from an amplitude-modulated signal. In one aspect, a device includes a sensing circuit operable to sense an amplitude-modulated signal having a carrier frequency. The device also includes a mixer operable to mix the amplitude-modulated signal with a mixing signal having a mixing frequency to provide a frequency-downshifted signal having an intermediate frequency less than the carrier frequency. The device also includes a filter operable to filter the frequency-downshifted signal to provide a filtered signal. The device further includes a sampler operable to undersample the filtered signal at an undersampling frequency to provide a digital signal, the digital signal being representative of a modulating signal.