Physiological Sensor Booster Circuit for Low-Loss Signal Buffering
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Solution Overview
Problem
Physiological sensors employing near-infrared spectroscopy face challenges with weak signals due to light absorption or dispersion by body tissues and short sampling times, as well as signal losses through cables, which affect data reliability and require complex amplifier configurations to mitigate noise and oscillations.
Innovation Solution
A booster circuit is integrated into the connector of physiological sensors, reducing input capacitance and buffering signals to enhance data reliability, allowing longer cables and compatible with existing equipment, comprising an operational amplifier, capacitor, and optionally a field effect transistor to maintain signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple sensors are placed in multiple locations and configured to sequentially operate, then different wavelengths of light can be detected at multiple locations, but the sampling time becomes too long to be reliable
Solution Approach 1:
The system divides the detection function across multiple sensors positioned at different locations, each capable of independent operation. This segmentation allows parallel detection at multiple locations rather than sequential measurement, reducing total sampling time while maintaining multi-location capability
2Productivity
If the sampling time is shortened to improve productivity, then the signal becomes too weak to be reliable when light is absorbed or dispersed by body tissue
Solution Approach 1:
The amplifier circuit provides signal amplification that counteracts the weakness caused by short sampling times and light absorption. The feedback resistor and capacitor network compensates for signal losses, maintaining reliable detection even when sampling time is reduced for higher productivity
3Reliability
If an amplifier with high feedback resistor value is used to minimize noise, then the amplifier performance is severely degraded and oscillations occur
Solution Approach 1:
The feedback resistor value is optimized to balance noise minimization with amplifier stability. The addition of a feedback capacitor modifies the frequency response to dampen oscillations while maintaining low-noise performance. This parameter optimization resolves the contradiction between noise reduction and amplifier performance
4Stability of the object's composition
If a capacitor is connected in parallel with the feedback resistor to dampen oscillations, then the bandwidth of the amplifier is reduced
Solution Approach 1:
The feedback capacitor value is carefully selected to provide sufficient oscillation damping while minimizing bandwidth reduction. The capacitor creates a frequency-dependent feedback network that stabilizes the amplifier at oscillation-prone frequencies while maintaining wide bandwidth for signal detection
5Ease of operation
If cables of any length are used to connect the light detector to the controller, then signal losses occur that affect data reliability
Solution Approach 1:
The amplifier circuit acts as an intermediary between the light detector and controller, compensating for signal losses in cables of various lengths. The active buffering and signal regeneration at the amplifier stage maintains signal integrity regardless of cable length, providing operational flexibility without sacrificing reliability
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 booster circuit significantly improves signal reliability and allows for longer cable lengths without significant signal loss, providing more accurate data and maintaining compatibility with existing medical sensor systems, thus enhancing diagnostic and monitoring capabilities.
Implementation Method 1
a booster circuit configured to buffer the signal and reduce input capacitance on either the controller or the connector
Implementation Method 2
A physiological sensor employing near-infrared spectroscopy may be used to detect characteristics of various body tissues by transmitting and receiving near-infrared light through the body tissue
Implementation Method 3
The sensors use spectroscopy to provide valuable information about the body tissue
Data Source
AI summary
A physiological sensor includes a light source in optical communication with a light detector. A controller is in communication with the light detector via a connector. A booster circuit is in communication with the light detector and the connector. The booster circuit may be configured to buffer signals generated by the light detector and reduce an input capacitance on either the controller or terminals of the connector. In various embodiments, the booster circuit may be disposed on the connector for a reusable cable or a disposable sensor pad.