Capacitive Sensor Calibration for Urine Measurement Variability
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Solution Overview
Problem
Conventional uroflowmetry tests conducted in clinical settings face challenges such as premature voiding and measurement errors due to patient discomfort and movement, making it difficult to accurately track urine volume, flow rate, and fluid management at home or remote locations.
Innovation Solution
A portable urine measurement device featuring a capacitive sensor system with multiple trigger points and sensors to accurately measure urine level, volume, and flow rate, integrated with a container and electronics portion for reliable data collection, and a calibration architecture to account for environmental and manufacturing variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive sensors are used in clinical settings, then measurement capability is provided, but sensitivity to manufacturing variability and environmental changes causes measurement errors
Solution Approach 1:
The system continuously monitors capacitance values and compares them against reference ranges to detect deviations caused by manufacturing variability or environmental changes. The feedback mechanism allows real-time compensation and calibration, maintaining measurement accuracy despite variations in sensor characteristics or operating conditions.
Solution Approach 2:
The patent employs multiple capacitance measurement parameters (C1, C2, C3, C4) corresponding to different sensor locations and configurations. By measuring multiple parameters simultaneously and analyzing their relationships, the system can distinguish between actual fluid level changes and spurious variations caused by manufacturing tolerances or environmental factors, thereby improving measurement reliability.
2Measurement precision
If multiple capacitive sensors with trigger points are implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The capacitive sensor system serves multiple functions: it measures urine level, calculates volume, determines flow rate, and provides calibration reference points. The same sensor infrastructure supports both clinical measurement modes and calibration operations, reducing the need for separate dedicated components and minimizing overall device complexity despite the multiple measurement capabilities.
Solution Approach 2:
The measurement range is divided into multiple segments defined by trigger points at known heights. Each trigger point corresponds to a specific capacitance value that marks a known urine level. This segmentation allows the system to use simple threshold-based detection for volume measurement while maintaining high precision across the entire measurement range, avoiding the need for complex continuous measurement algorithms.
3Reliability
If calibration architecture is added to account for environmental variability, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The calibration system uses the device's own capacitive sensors and the container's known geometry to perform self-calibration. By measuring capacitance at known reference volumes (trigger points) and calculating calibration factors from these measurements, the system eliminates the need for external calibration equipment or complex reference standards, achieving reliable environmental compensation through self-contained procedures.
Solution Approach 2:
Calibration is performed before actual urine measurement to establish baseline capacitance values and calibration factors. The system pre-determines the relationship between capacitance and volume for the specific container-sensor configuration, storing these calibration parameters for use during measurement. This preliminary calibration action separates the complexity of environmental compensation from the actual measurement process, simplifying real-time operation.
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 device enables precise and reliable measurement of urine parameters, reducing errors and allowing for effective fluid management at home, thereby improving patient outcomes and reducing hospital readmission rates for heart failure patients.
Implementation Method 1
a first capacitive sensor configured to measure a first capacitance within a contained volume having known dimensions, wherein the first capacitance changes as a substance is received into the contained volume
Implementation Method 2
a second capacitive sensor having a plurality of trigger points at a plurality of corresponding known heights within the contained volume, the second capacitive sensor configured to detect when the substance received into the contained volume has reached each of the corresponding known heights within the contained volume
Data Source
AI summary
A printed circuit board device includes: a first capacitive sensor configured to measure a first capacitance within a contained volume having known dimensions, wherein the first capacitance changes as a substance is received into the contained volume; a second capacitive sensor having a plurality of trigger points at a plurality of corresponding known heights within the contained volume, the second capacitive sensor configured to detect when the substance received into the contained volume has reached each of the corresponding known heights within the contained volume; and wherein at least one of a level of the substance within the contained volume, a volume of the substance within the contained volume, or a flow rate of the substance into the contained volume is determined based on data from the first capacitive sensor and the second capacitive sensor.