Portable Micro-Flow Measurement Bench for Medical Pump Testing
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Solution Overview
Problem
Existing methods for measuring micro-flows, particularly in medical insulin pumps, are inadequate for real-time detection of flow irregularities under variable atmospheric conditions and require lengthy measurement times, often taking up to 150 hours for low flow rates, which is impractical for pediatric insulin delivery and other applications.
Innovation Solution
A portable measuring bench that combines two measurement methods for quasi-instantaneous and average flow detection using continuous bubble visualization in a micro-capillary, with adjustable back pressure and temperature control, allowing for real-time monitoring and automatic safety stops to prevent occlusion, and includes a Peltier effect module for thermal regulation and a micropipette for precise flow measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing thermal flow meter methods are used, then measurement precision can be achieved, but measurement time becomes excessively long (up to 150 hours for low flow rates)
Solution Approach 1:
The measurement process is segmented into two complementary methods: (1) thermal flow measurement for average flow rate over long periods, and (2) optical bubble tracking for instantaneous flow rate. This segmentation allows each method to be used for its optimal purpose, resolving the contradiction between precision and time by providing both long-term accurate measurements and quick instantaneous readings.
Solution Approach 2:
A bubble is introduced as an intermediary element in the liquid flow to enable optical measurement. The bubble acts as a visual marker that can be tracked by optical sensors to determine instantaneous flow rate, providing a bridge between thermal measurement precision and optical measurement speed.
2Adaptability or versatility
If thermal flow measurement is used under variable atmospheric conditions, then measurement can be performed, but thermal stability requirements cause long waiting periods between measurements
Solution Approach 1:
The optical bubble tracking method enables continuous instantaneous measurement without requiring thermal stability waiting periods. While thermal measurements continue periodically for average flow rate, the optical system operates continuously, eliminating dead time and allowing measurements under variable atmospheric conditions without thermal stability constraints.
3Reliability
If micro-pump operates under high back pressure, then pump performance can be tested, but occlusion problems may occur requiring safety shutdown
Solution Approach 1:
The system implements feedback through continuous instantaneous flow rate monitoring using optical bubble tracking. When flow rate drops below a threshold indicating potential occlusion, the system provides immediate feedback to trigger safety shutdown, allowing reliable high-pressure testing while preventing harmful occlusion events.
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 instantaneous detection of micro-pump irregularities, allows for testing under controlled temperature and pressure conditions, and ensures precise and reliable measurements, facilitating automated analysis and use outside specialized laboratories.
Implementation Method 1
The bench is arranged in a sealed and thermally insulated box, including means for temperature and pressure control; the temperature control means is a Peltier effect module, located in the box, which is capable of regulating the temperature
Implementation Method 2
The measurement principle is based on detecting the passage of bubbles in calibration pipettes, using optical sensors
Data Source
Figure 1
Figure 2~3
AI summary
The purpose of the invention is to provide reliable and precise values for liquid micro-flows supplied by a pump (30) using a customised follow-up for detecting operational irregularities in a quasi-instantaneous manner and under variable temperature and/or atmospheric pressure conditions. Accordingly, the invention provides (10) coupling two complementary measurement means, i.e. an average measurement and an instantaneous measurement of the flow. In one embodiment, the micro-pump (30) to be tested is arranged in a housing (20) and comprises temperature and pressure control means (22, 24) for making at least two complementary measurements of the flows, i.e. average and instant flows, following a gas micro-bubble (119) in a micro-pipette (120). The bubble is inserted into the liquid by an injection pad (110) provided with a pressure sensor (112) dedicated to the measurement of the counter-pressure of the pump (30). The flow measurements are respectively made by two optical sensors (124a, 124b) and a camera (126) that transmit the data to a data processing unit (129). The pump (30) is connected on a connection pad (100, 102, 104) of a specific sensor (106) for measuring the clogging pressure. The counter-pressure is adjusted at the outlet of the micro-pipette (120) by a variable opening (130) controlled by the processing unit (129).