Microdosing Device Using Shape Memory Alloy Actuators
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Solution Overview
Problem
Conventional pipetting devices are inefficient in accurately dispensing microvolumes due to systematic and random errors, particularly when dealing with microfluids, as they are affected by factors like satellite droplet formation, surface tension, and geometric conditions, leading to unreliable delivery of volumes in the sub-microliter range.
Innovation Solution
A micro-dosing device utilizing shape memory alloy (SMA) actuators to generate a micro-free jet by abruptly displacing a predetermined micro-volume, with SMA actuators providing high energy density and operating at low voltages, enabling precise and efficient delivery of microfluids through a microdosing chamber with a stop device and SMA actuator arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional piston-operated pipettes are used to dose small volumes, then the device structure is simple and easy to manufacture, but the dosing precision and reliability deteriorate due to systematic and random errors
Solution Approach 1:
The patent replaces the conventional mechanical piston-operated system with a piezoelectric actuator that uses ultrasonic vibrations to generate acoustic pressure waves. This substitution eliminates the systematic errors associated with mechanical displacement and surface tension effects, achieving reliable dosing of microvolumes (0.1-1.0 μl) through acoustic field control rather than direct mechanical contact.
Solution Approach 2:
The piezoelectric actuator generates periodic ultrasonic vibrations at specific frequencies to create acoustic pressure waves that propel fluid samples. This periodic action allows precise control of fluid ejection timing and velocity, enabling accurate dosing of small volumes by controlling the number and size of droplets ejected during each vibration cycle.
2Reliability
If free jet method is used to dispense microvolumes, then the delivery speed is improved, but the reliability deteriorates due to satellite droplet formation and incomplete ejection
Solution Approach 1:
The piezoelectric actuator generates ultrasonic mechanical vibrations that create controlled acoustic pressure waves within the pipette tip. These vibrations provide the kinetic energy needed to eject fluid as a free jet while maintaining precise control over droplet formation, preventing satellite droplet formation by ensuring complete and controlled ejection of the intended volume.
Solution Approach 2:
The patent changes the physical parameters of fluid ejection by using acoustic pressure waves instead of simple mechanical pressure. By controlling the frequency, amplitude, and duration of ultrasonic vibrations, the system can precisely control droplet size, ejection velocity, and timing, thereby eliminating the harmful effects of incomplete ejection and satellite droplet formation while maintaining free jet delivery reliability.
3Use of energy by moving object
If conventional actuators are used in microdosing devices, then the device complexity is low, but the energy density and precision deteriorate
Solution Approach 1:
The patent replaces conventional mechanical actuators with a piezoelectric actuator that converts electrical energy directly into mechanical vibrations through the piezoelectric effect. This substitution provides high energy density and precise control of microfluid ejection, as the piezoelectric material can generate rapid, high-frequency vibrations with controlled amplitude and duration, enabling accurate dosing of microvolumes.
Solution Approach 2:
The piezoelectric actuator utilizes the phase transition properties of piezoelectric materials, which can rapidly change their physical state between polarized and depolarized conditions in response to electrical fields. This allows the actuator to generate rapid, high-frequency vibrations with precise control over energy output, achieving high energy density in a compact form factor suitable for portable microdosing devices.
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 micro-dosing device achieves precise and reliable generation of micro-free jets in the sub-microliter range, overcoming the limitations of conventional devices by ensuring accurate and efficient delivery of microfluids with reduced systematic and random errors.
Implementation Method 1
A micro-dosing device for generating a micro-dosing volume of a fluid sample in the form of a micro-free jet by abruptly displacing a predetermined micro-volume with a stop device and/or shape memory material actuator
Implementation Method 2
a displacement element which is set up for deflection between a first position and a second position and for displacing a micro-volume of the microdosing chamber
Data Source
Figure 1a~4b
Figure 5a~7c
Figure 8a~10
AI summary
The invention relates in particular to a microdosing device for generating a microdosing volume of a fluid sample in the form of a micro free jet by abruptly displacing a predetermined micro volume.