Wax Micro Actuator with Semiconductor Heating for Infusion Pumps
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing micro-pumps for therapeutic product infusion systems face challenges in reducing size while maintaining sufficient driving force for efficient, leak-free, and reliable pumping, particularly due to inefficiencies in heating mechanisms and heat distribution in wax actuators.
Innovation Solution
A thermally efficient micro-actuator using a semiconductor element to heat a blend of paraffin waxes within a cavity, positioned adjacent the diaphragm to ensure uniform heating and controlled phase change, with a gearing system to amplify displacement, and valves with differential activation pressures to prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the actuator is reduced for use in micro-fluidic systems, then the device complexity and size are improved, but the driving force becomes substantially reduced
Solution Approach 1:
The patent employs a wax-based phase change material that transitions from solid to liquid state, utilizing the volume expansion during phase transition to generate mechanical displacement and driving force in the actuator, thereby maintaining sufficient force output in a miniaturized configuration
Solution Approach 2:
The wax material undergoes thermal expansion when heated, increasing in volume to push against the diaphragm and generate the necessary driving force for pumping, allowing the small actuator to produce adequate mechanical work despite its reduced size
2Temperature
If conventional heating mechanisms are used in wax actuators, then the actuator can be operated, but thermal runaway occurs and temperature control becomes inaccurate
Solution Approach 1:
The patent incorporates a temperature sensor that provides feedback to the control system, enabling real-time monitoring and adjustment of heating power to maintain the wax material at its precise melting point and prevent thermal runaway
Solution Approach 2:
The control system dynamically adjusts the heating parameters based on temperature feedback, modulating the power delivery to match the thermal requirements of the phase change material and ensuring stable operation
3Temperature
If the heating element is positioned away from the diaphragm, then the actuator structure is simpler, but heat distribution becomes non-uniform and phase change control is reduced
Solution Approach 1:
The heating element is strategically positioned adjacent to the diaphragm to create a localized heat source that directly induces phase change in the wax material at the critical location, ensuring uniform heat distribution where needed most for precise actuation control
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 solution provides a compact, accurately controllable, and scalable actuator that ensures efficient pumping of therapeutic products, preventing thermal runaway and achieving precise temperature control, suitable for micro-infusion systems.
Implementation Method 1
a semiconductor element (6) disposed within the cavity, wherein the semiconductor element is adapted to heat the working medium to cause it to undergo the phase change into the liquid state
Implementation Method 2
a working medium (3) that reversibly expands as it undergoes a phase change from a solid to a liquid state
Implementation Method 3
the specific volume of polymer increases. With further heat input from the heater layer, the HAPP portion undergoes a phase transition. During the phase transition, the specific volume increases dramatically
Data Source
Figure 1~3
Figure 4a~4d
Figure 5~6
AI summary
An actuator comprises a cavity (2) containing a working medium (3) that reversibly expands as it undergoes a phase change from a solid to a liquid state, a diaphragm (4) disposed adjacent the cavity such that expansion and contraction of the expandable working medium causes the diaphragm to deflect, and a semiconductor element (6) disposed in the cavity, wherein the semiconductor element is adapted to heat the working medium to cause it to undergo the phase change into the liquid state. The actuator may be used in a pump for an infusion system.