Portable Level Sensor for Flexible Medical Bags
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Solution Overview
Problem
Stoma and urine bag users lack a means to monitor the bag's filling level accurately between empty and full, leading to potential overfilling, bursting, or detachment, as existing sensors provide only a single alarm level without progressive filling information.
Innovation Solution
A portable level sensor with a flexible resistor element that changes resistance with flexing, attached to the bag, periodically polls its resistance and transmits signals wirelessly to a receiver, allowing for continuous monitoring of the bag's fullness level, using a microprocessor and Bluetooth module, and optionally an accelerometer for orientation correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a single alarm level sensor is used, then the device complexity is reduced, but the information provided to the user about bag fullness is insufficient
Solution Approach 1:
The sensing range is divided into multiple discrete levels (e.g., 25%, 50%, 75%, 100% fullness) by positioning multiple resistive elements at different locations on the bag surface. Each element monitors a specific fill level, and the system reports which level is currently reached, providing progressive information without requiring a continuous complex measurement system.
2Reliability
If the bag is monitored continuously for fullness, then user safety is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous monitoring, the system periodically polls the resistance values of the sensor elements at predetermined intervals. The microcontroller activates the ADC converter only at these periodic intervals to read resistance values, significantly reducing power consumption while still providing reliable monitoring and timely alarm notifications when fill levels are reached.
3Ease of operation
If the sensor system is made portable with wireless transmission, then user convenience is improved, but device complexity increases
Solution Approach 1:
The mechanical/wired connection system is replaced with a wireless communication system. The microcontroller reads resistance values via ADC and transmits the fullness level data wirelessly to a remote receiver or display device, eliminating the need for complex wired connections and making the system portable and easier to operate.
4Measurement precision
If multiple resistive elements are used to provide progressive fullness levels, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Different regions of the bag surface are equipped with resistive elements having different resistance characteristics. Elements positioned at different locations have resistance values calibrated to correspond to specific fill levels (25%, 50%, 75%, 100%). This local differentiation provides precise measurement of bag fullness at multiple discrete levels without requiring a single complex continuous measurement system.
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
Enables users to track the progressive filling of the bag, providing timely alerts and accurate volume measurements, even when the bag is not in the upright position, thus preventing overfilling and improving user safety.
Implementation Method 1
a flexible resistor element, having an electrical resistance that changes in dependence upon its degree of flexing
Data Source
AI summary
A portable level sensor for a flexible bag for collecting a fluid and/or a solid, and a system and method for sensing the content level of a flexible bag using the portable level sensor. The sensor comprises a flexible resistor element with an electrical resistance that changes in dependence upon its degree of flexing, means for attaching the resistor element to an outside surface of the flexible bag and means for periodically polling the electrical resistance of the resistor element and transmitting to a receiver a signal which varies in dependence on the said electrical resistance.