Piezo Peristaltic Micropump Cycle Volume Control
Solution Overview
Problem
Existing micropumps used for delivering medical fluids face challenges in controlling the flow rate of liquids, which varies with fluid pressure downstream, making precise control of liquid delivery difficult in certain applications.
Innovation Solution
A liquid injection system incorporating a peristaltic pump with a central chamber whose volume is controlled by a deformable membrane actuated by piezoelectric actuators, coupled with a control circuit and sensor to adjust the volume delivered based on real-time feedback, allowing for precise control of the liquid volume per cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a peristaltic pump with piezoelectric actuators is used to deliver liquid, then the pump can operate with compact size and simple structure, but the flow rate varies with downstream fluid pressure making precise control difficult
Solution Approach 1:
A sensor measures the actual liquid volume delivered during each cycle and provides feedback to a control circuit. The control circuit compares the measured volume with a target volume and adjusts the piezoelectric actuator's drive signal accordingly to correct any deviation, thereby achieving precise flow rate control despite variations in downstream pressure
Solution Approach 2:
The system dynamically adjusts the drive parameters (voltage amplitude, pulse width, or frequency) of the piezoelectric actuator based on feedback from the sensor. By changing these parameters in real-time, the system compensates for pressure variations and maintains accurate control of the liquid volume delivered per cycle
2Quantity of substance
If the flow rate is reduced to achieve low flow rate delivery, then the pump can deliver precise small volumes, but the flow rate becomes highly sensitive to downstream pressure variations
Solution Approach 1:
The sensor continuously monitors the actual liquid volume delivered and provides real-time feedback to the control circuit. This feedback mechanism detects even small deviations caused by pressure variations and triggers corrective adjustments to the actuator drive signal, ensuring reliable and consistent low flow rate delivery
Solution Approach 2:
The system transitions from static operation to dynamic control by continuously adjusting the actuator parameters based on real-time feedback. This dynamic adjustment capability allows the system to maintain reliable low flow rate delivery by compensating for pressure variations as they occur during 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
Enables precise control of the liquid volume delivered per cycle, allowing for consistent flow rates even at low flow rates, by modulating the actuation voltage and frequency, thereby addressing the variability in flow rates due to fluid pressure.
Implementation Method 1
a silicon micro-pump comprising one or more membrane(s) deformed by piezoelectric actuators
Data Source
Figure 1A~1D
Figure 1E~2
Figure 3~4
AI summary
The invention relates to a system for delivering a liquid, comprising: - a peristaltic pump (1) operating in cycles so that an elementary volume of liquid is delivered into the pipe during the course of each cycle, - at least one actuator (511, 512, 513) able to cause the pump to deliver a volume of liquid, during the course of a cycle, - a control circuit (55, 56, 58, 62), for applying a control signal to the actuator so that the volume delivered during the course of a cycle is dependent on this signal applied to the actuator, - a sensor (54, 60), able to produce a signal indicative of the quantity of liquid ejected during the course of a cycle, - the control circuit (55, 56, 58, 62) being able to determine a control signal on the basis of said signal from the sensor and of a reference signal (VD, VS).