Optical Sensor Contact State Detection via Impedance Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Bio-signal measuring techniques, particularly using optical sensors, face challenges in maintaining accuracy and reproducibility due to varying contact states between the sensor and the object, leading to noise in measured signals.
Innovation Solution
A bio-signal measuring apparatus with a photodetector and a light source array, including concentric ring-shaped electrodes, measures impedance to determine contact state and location of contact failure, allowing for adjustment of measurement and estimation of bio-information such as blood pressure and vascular age.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical sensor is used to measure bio-signal, then measurement capability is provided, but measurement accuracy deteriorates due to noise from varying contact states
Solution Approach 1:
The patent introduces impedance measurement as an intermediary indicator to assess contact state. The impedance measurer measures impedance between electrodes and object, and the processor uses this impedance information to determine contact state quality, thereby indirectly detecting and compensating for contact-related noise in optical signals without directly interfering with the optical measurement process
Solution Approach 2:
The system implements feedback by continuously monitoring impedance changes and using this information to adjust or correct optical signal measurements. The processor determines contact state based on impedance measurements and uses this feedback to identify when noise is introduced, enabling real-time compensation or rejection of degraded measurements
2Measurement precision
If contact state is not monitored, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent makes the measuring apparatus multi-functional by integrating both optical signal measurement and impedance measurement capabilities into a single device. The same processor handles both types of measurements and coordinates their results, allowing the system to monitor contact state without requiring a completely separate monitoring system
Solution Approach 2:
Impedance measurement serves as an intermediary mechanism that provides contact state information with minimal additional complexity. Rather than implementing complex direct contact detection systems, the patent uses impedance as a simple electrical proxy that correlates with contact quality, enabling precision monitoring through a relatively simple additional measurement channel
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 apparatus ensures accurate bio-signal measurement by determining and adjusting for contact state, enhancing the reliability of bio-information estimation and reducing noise in optical signals.
Implementation Method 1
an impedance measurer configured to measure an impedance of an object, using the first electrode and the second electrode
Implementation Method 2
an optical sensor including a photodetector and a light source array disposed around the photodetector
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A bio-signal measuring apparatus includes an optical sensor including a photodetector and a light source array disposed around the photodetector, a first electrode disposed between the photodetector and the light source array, and a second electrode disposed on an outer periphery of the light source array. The bio-signal measuring apparatus further includes an impedance measurer configured to measure an impedance of an object, using the first electrode and the second electrode, and a processor configured to determine a contact state between the object and the optical sensor, based on the measured impedance.