Smartphone Biosensor Noise Reduction via Thumb-Centric Switch Layout
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Solution Overview
Problem
Existing mobile apparatuses with biosensors face challenges in minimizing body movement noise when obtaining biosignals, especially during normal operations like using a smartphone, as noise from other body parts interferes with the signal, making it difficult to obtain accurate and continuous data like pulse rate or heart beat.
Innovation Solution
The mobile apparatus rearranges operation switches along a circular arc centered at the carpometacarpal joint of the thumb, suppressing movements of other fingers and palms, and uses photoelectric pulse wave sensors to stabilize the biosignal measurement by changing the switch arrangement based on hand position and operation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a biosensor is provided at a position with which the hand of a user is in contact while the user is operating a mobile apparatus, then biological information can be obtained during normal operations, but body movement noise from portions other than the measuring finger will be superimposed on the sensor output signal
Solution Approach 1:
The operation switches are segmented and arranged along a circular arc path that corresponds to the natural movement trajectory of the thumb. This segmentation isolates the thumb's movement from other fingers, allowing the biosensor to capture signals from only the measuring finger while excluding noise from other body parts.
Solution Approach 2:
The operation switches are arranged along a circular arc rather than a straight line or grid pattern. This curved arrangement matches the spherical/curved path of thumb movement around the carpometacarpal joint, ensuring that only the thumb tip contacts the switches during operation, thereby preventing noise from other fingers.
2Ease of operation
If operation switches are arranged in a conventional layout, then ease of operation is maintained, but body movement noise interferes with biosignal measurement
Solution Approach 1:
The operation switches are arranged along a circular arc that follows the natural curved path of thumb movement. This curved layout maintains ease of operation by matching human ergonomics while simultaneously ensuring that only the thumb tip contacts the switches, preventing noise from other fingers during normal operation.
Solution Approach 2:
The switch arrangement is optimized for the specific local area of thumb contact. By positioning switches along the circular arc corresponding to thumb movement, the design ensures that only the thumb tip (the measuring portion) interacts with the switches, while other fingers remain excluded from the operation area.
3Loss of time
If measurement is performed during continuous operations, then real-time data can be obtained, but the influence of body movement noise increases over time
Solution Approach 1:
By segmenting the operation switches along a circular arc and restricting operation to the thumb only, the system maintains consistent signal quality over extended periods. The segmentation prevents other fingers from introducing noise during continuous operation, allowing real-time data collection without degradation of measurement precision.
Solution Approach 2:
The thumb performs dual functions: it operates the mobile apparatus by pressing the circular arc arranged switches while simultaneously serving as the measuring portion for the biosensor. This self-service arrangement ensures that the measuring finger remains stationary relative to the sensor during operation, preventing noise contamination over time.
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 approach effectively reduces body movement noise, allowing for stable and accurate biosignal measurement during smartphone use by aligning switches with thumb movements, enhancing the reliability of pulse rate and other biosignal data acquisition.
Implementation Method 1
photoelectric pulse wave sensors to stabilize the biosignal measurement
Data Source
Figure 1
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AI summary
A smart phone (1) includes photoelectric pulse wave sensing units (41 and 42) that obtain photoelectric pulse wave signals from hands holding the smart phone, a touch screen (21) on which a plurality of operation switches (31) that accept operations performed by thumbs are displayed, and a switch arrangement changing unit (111) that changes the arrangement of the displayed plurality of operation switches (31). The switch arrangement changing unit (111), when photoelectric pulse wave signals are obtained by the photoelectric pulse wave sensing units (41 and 42), changes the arrangement of the operation switches (31) displayed on the touch screen (21) in such a manner that the operation switches (31) are arranged along a circular arc (510) of a virtual circle whose center is located at a carpometacarpal joint (500) of the thumb of a right hand (501) performing operations and whose radius is the distance from the carpometacarpal joint (500) to the tip of the thumb.