Pulse Oximeter Signal Processing for Low-Perfusion Accuracy
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Solution Overview
Problem
Existing blood oxygen concentration measurement devices struggle with accuracy when signal intensity is ≤0.3%, leading to incorrect diagnoses due to low perfusion, particularly in peripheral tissues with reduced blood circulation.
Innovation Solution
A blood oxygen concentration measurement device and method that includes a light source unit, light detection unit, signal processing circuit, and control unit, which processes signals to calculate blood oxygen value, pulse rate, and signal strength index, adjusting parameters to enhance accuracy and convenience, especially in low perfusion conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If general oximeter is used for blood oxygen measurement, then device simplicity is maintained, but measurement accuracy deteriorates under low perfusion conditions (signal intensity ≤0.3%)
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting measurement parameters based on perfusion conditions. The system calculates a perfusion index from the PPG signal and adjusts measurement parameters accordingly - when low perfusion is detected (signal intensity ≤0.3%), the system switches to alternative measurement modes or algorithms to maintain accuracy despite poor blood circulation in peripheral tissues
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring the PPG signal quality and perfusion index, then using this information to adjust subsequent measurements. The system evaluates signal strength and characteristics in real-time, and when degradation is detected, it activates compensatory algorithms or alerts the user to reposition the device, ensuring maintained measurement accuracy under varying perfusion conditions
2Measurement precision
If signal processing complexity is increased to handle low perfusion conditions, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies dynamics by implementing adaptive signal processing that adjusts its complexity based on actual measurement conditions. The system starts with standard processing algorithms and dynamically increases processing sophistication only when low perfusion conditions are detected - switching to enhanced algorithms, multiple wavelength analysis, or alternative calculation methods only when necessary, thereby maintaining accuracy while minimizing unnecessary complexity
Solution Approach 2:
The patent applies local quality by applying different levels of signal processing to different segments of the PPG signal or to different measurement channels. Rather than uniformly complex processing across all signals, the system applies enhanced processing only to specific signal portions or channels that exhibit low perfusion characteristics, while using simpler processing for adequate signals, thus optimizing the balance between accuracy and complexity
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
Enhances the accuracy of blood oxygen concentration measurements and convenience by improving signal processing and parameter adjustments, effectively handling low perfusion states.
Implementation Method 1
a light source unit (110), a light detection unit (120), wherein the light source unit is configured to generate a light signal, the light detection unit is configured to receive a penetrating signal generated by the light signal penetrating an object
Data Source
AI summary
A blood oxygen concentration measurement device includes a light source unit, a light detection unit, a signal processing circuit, and a control unit. The light source generates a light signal. The light detection unit receives a penetrating signal generated by the light signal penetrating an object to generate a detection signal. The signal processing circuit receives the detection signal and processes the detection signal to generate a first processing signal. The control unit receives the first processing signal, calculates the blood oxygen value, the pulse rate and the signal strength index according to the first processing signal, and outputs the blood oxygen value, the pulse rate, and the signal strength index, or performs a low perfusion signal measurement process according to the signal strength index and the first predetermined index.