Pixelated Vital Sensor Selective Illumination for Accuracy
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Solution Overview
Problem
Conventional vital sensors, such as pulse oximeters, face challenges in achieving high measurement accuracy and reliability while maintaining low energy consumption, particularly in wearable devices, due to the low amplitude of the pulsating signal compared to the DC signal and sensitivity to skin type variations and positioning.
Innovation Solution
A vital sensor with a pixelated emitter array and optical elements that direct light to specific areas of high arterial density on the skin, using an evaluation unit to control pixels based on reference values for AC/DC signal ratio and adapt to skin conditions, reducing energy consumption and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional vital sensors illuminate the entire skin area, then measurement coverage is complete, but energy consumption increases and AC/DC signal ratio decreases
Solution Approach 1:
The emitter array is divided into multiple independently controllable pixels that can be selectively activated. The evaluation unit determines reference values for each pixel and selectively activates only those pixels corresponding to areas with high arterial density, thereby reducing overall energy consumption while maintaining measurement precision in the most relevant areas.
Solution Approach 2:
Different areas of the skin are treated differently based on their arterial density characteristics. The system identifies and prioritizes illumination of areas with high arterial density where the AC signal is most prominent, while reducing or eliminating illumination of areas with low arterial density, thus optimizing the AC/DC signal ratio and energy efficiency.
2Reliability
If all pixels are activated for measurement, then complete skin area coverage is achieved, but energy consumption increases
Solution Approach 1:
Before actual vital parameter measurement, the system performs a preliminary reference value determination for each pixel by illuminating the skin and evaluating the AC/DC signal ratio. Based on these preliminary results, the evaluation unit creates a selective activation map that identifies which pixels will contribute most effectively to accurate measurement, allowing full measurement accuracy to be achieved with reduced energy consumption.
Solution Approach 2:
The system continuously monitors the AC/DC signal ratio for each pixel during reference value determination and uses this feedback information to guide subsequent pixel activation decisions. Pixels with high AC/DC ratios are selected for active measurement, while those with low ratios are deactivated, creating a closed-loop system that optimizes both accuracy and energy efficiency.
3Measurement precision
If light is directed to areas with low arterial density, then complete coverage is achieved, but measurement accuracy decreases
Solution Approach 1:
The system extracts and isolates the most informative pixels for measurement based on their AC/DC signal ratio characteristics. By removing or deactivating pixels corresponding to areas with low arterial density that contribute minimally to measurement accuracy, the system achieves high measurement precision with reduced illuminated area, focusing resources only on the most effective measurement locations.
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 enhances the AC/DC signal ratio and reduces energy consumption by selectively illuminating areas with high arterial density, leading to more accurate vital parameter measurements and extended battery life in wearable devices.
Implementation Method 1
at least one pixelated emitter array (3) with a first pixel (3.1) and at least one second pixel (3.2), each of which is configured to emit light of a wavelength range
Implementation Method 2
at least one optical element (5) which is arranged between the at least one pixelated emitter array (3) and the projection surface and which is configured to direct light from the first pixel (3.1) onto a first region (11.1) of the projection surface
Implementation Method 3
at least one photodetector (2), which is configured to detect the light emitted by the pixels and reflected on the projection surface
Implementation Method 4
measures changes in light absorption based on the light reflected back from the skin
Data Source
AI summary
A vital sensor includes at least one pixelated emitter array with first and second pixels. The pixels are configured to emit light of a wavelength range in the direction of a projection surface. The vital sensor also includes an optical element, arranged between the at least one pixelated emitter array and the projection surface, and which is configured to direct light of the first pixel onto a first region of the projection surface and light of the second pixel onto a second region of the projection surface which differs from the first region. The vital sensor further includes a photodetector configured to detect the light emitted by the pixels and reflected on the projection surface. The vital sensor additionally includes an evaluation unit configured to control the first pixel and the at least one second pixel in a pulsed and time-sequential manner to determine a first reference value.