Bathroom Scale Heart Rate Detection via Strain Gauge and Impedance Fusion
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Solution Overview
Problem
Existing electronic bathroom scales struggle to accurately measure heart rate for a significant portion of the population, and impedance measurement methods require users to be barefoot, limiting their effectiveness.
Innovation Solution
The electronic bathroom scale incorporates four conductive portions and strain gauges connected to an electronic unit that measures weight and impedance variations, using pulsed current injection and inter-correlation calculations to enhance signal quality and reliability, allowing heart rate measurement for most individuals without the need for barefoot usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strain gauge measurement is used to evaluate heart rate, then heart rate measurement is possible for some users, but measurement reliability deteriorates for a significant portion of the population
Solution Approach 1:
The patent combines strain gauge measurements with impedance measurements to create a hybrid system. The electronic unit processes both signals and determines heart rate from either measurement method depending on which provides reliable results, thereby resolving the contradiction between reliability for individual users and overall adaptability across the population.
Solution Approach 2:
The system dynamically switches between measurement methods based on signal quality assessment. The electronic unit evaluates the reliability of strain gauge signals and impedance signals in real-time, selecting the most reliable method for each user, thus adapting the measurement approach to individual physiological characteristics.
2Reliability
If impedance measurement is used to evaluate heart rate, then heart rate can be measured for some users, but the method requires barefoot usage which limits ease of operation
Solution Approach 1:
The scale is designed to perform multiple measurement functions: it can measure heart rate through strain gauges (works with shoes on), through impedance (works barefoot), or through a combination of both. This multi-functionality allows the system to adapt to different user conditions and eliminates the strict barefoot requirement while maintaining measurement reliability.
Solution Approach 2:
The electronic unit acts as an intermediary that processes both strain gauge and impedance signals, selecting the most reliable measurement source. This intermediary processing allows the system to overcome the limitations of each individual method and provide reliable heart rate measurement regardless of whether the user is barefoot or wearing shoes.
3Reliability
If pulsed current is used for impedance measurement, then measurement reliability improves, but energy consumption increases
Solution Approach 1:
The system uses pulsed current instead of continuous current for impedance measurement. The current is applied in periodic pulses, allowing the measurement to be performed with intermittent energy input rather than continuous energy consumption, thereby reducing overall energy usage while maintaining measurement reliability during the pulse periods.
Solution Approach 2:
The system applies current pulses only when impedance measurement is needed and only at the level necessary to obtain reliable measurements. The electronic unit manages the pulsing strategy to achieve sufficient signal quality without excessive energy consumption, using partial action rather than continuous full-power current application.
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
This solution provides a reliable heart rate measurement for a broader range of individuals by combining weight and impedance signals, improving accuracy and coverage, and reducing measurement errors.
Implementation Method 1
each foot comprising measuring means, in this case a strain gauge
Implementation Method 2
measuring a second signal representative of the periodic impedance variations generated by the user's heartbeat
Data Source
Figure 1~2
Figure 3~9
Figure 4~5
AI summary
Weighing device of the electronic bathroom scales type (1) comprising four feet (41-44) each having a strain gauge, four conducting portions (61-64) on the top surface and one electronic control unit (4), the electronic unit being configured to measure first signals indicative of the periodic variations in weight and second signals indicative of periodic variations in impedance caused by the beating of the heart of the user, the electronic unit being configured to determine the heart rate of the user from the first and second signals. Method for determining the heart rate of the user from the first and second signals.