Voltage-Controlled Oscillator for Low-Power Glucose Measurement
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Solution Overview
Problem
Existing non-invasive glucose measurement devices require careful calibration and operate best under specific conditions to achieve high accuracy, and they often consume high power and require higher supply voltages, which is not ideal for portable devices.
Innovation Solution
The device incorporates a voltage-controlled oscillator with a voltage-controlled amplifier and capacitor, allowing operation at low DC-voltages, and uses a processing circuit with a diode and integrator for signal rectification and smoothing, along with a method that fits a function to measurement values across various frequencies to determine glucose levels accurately, while also using an asymmetric electrode design and biologically inert materials for improved compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage-controlled oscillator is used for generating AC voltage in a given frequency range, then the device can measure glucose levels non-invasively, but the power consumption and supply voltage requirements become high
Solution Approach 1:
The patent implements a dynamic gain control mechanism that automatically adjusts the amplifier gain based on the DC voltage level detected by the microprocessor. When the DC voltage component becomes significant (indicating operation near the loss maximum of the voltage-controlled capacitor), the system increases the amplifier gain to compensate, thereby maintaining measurement accuracy across varying operating conditions while enabling low-voltage operation
Solution Approach 2:
The system performs self-diagnosis and self-adjustment by continuously monitoring the DC voltage component in the output signal and automatically compensating for changes in capacitor loss characteristics. This self-regulating mechanism eliminates the need for external calibration under different voltage conditions, allowing the device to maintain accuracy while operating at low supply voltages
2Measurement precision
If the device operates under well-defined conditions with careful calibration to achieve high accuracy, then measurement precision is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The microprocessor automatically detects the DC voltage component in the output signal and uses this information to dynamically adjust the amplifier gain. This self-calibrating mechanism eliminates the need for manual calibration procedures and external reference measurements, maintaining high measurement accuracy while significantly simplifying the device operation and reducing calibration complexity
3Measurement precision
If the gain of the voltage-controlled amplifier is increased to compensate for high loss in the voltage-controlled capacitor, then measurement accuracy is maintained, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the amplifier gain only when necessary - specifically when the microprocessor detects that the DC voltage component indicates operation near the loss maximum of the voltage-controlled capacitor. This conditional, adaptive gain control maintains signal accuracy only when needed, avoiding continuous high-power consumption and enabling efficient low-voltage operation during normal conditions
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 solution enables accurate glucose measurement with reduced power consumption and compatibility, allowing for efficient data exploitation and improved physiological compatibility by minimizing noise and ensuring reliable signals.
Implementation Method 1
at least one tank circuit with a voltage-controlled capacitor determining a frequency of operation of the VCO
Implementation Method 2
the processing circuitry comprises at least one diode for rectifying an AC input voltage and generating a rectified signal
Implementation Method 3
an integrator for smoothing the same
Data Source
AI summary
A device for measuring the glucose level in living tissue has electrodes (5, 6) for being brought into contact with the specimen and a voltage-controlled oscillator (31) as a signal source for generating an AC voltage in a given frequency range. The AC voltage is applied to the electrodes (5, 6). A voltage over the electrodes is fed to a processing circuitry (37, 38), which converts it to the glucose level using calibration data. The voltage-controlled oscillator (31) has a symmetric design with adjustable gain for generating signals in a large frequency range with low distortions at a low supply voltage. The processing circuit comprises a simple rectifier network with software-based correction. The electrodes (5, 6) are of asymmetric design and optimized for biological compatibility.