In-Plane Electromagnetic MEMS Pump for Transdermal Drug Delivery
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Solution Overview
Problem
Existing microelectromechanical systems (MEMS) piezoelectric micropumps face limitations such as limited throw, high actuation voltages, low resonant frequency, and difficulty in passing large particles due to complex structures and vertical fabrication challenges, making them expensive and difficult to manufacture.
Innovation Solution
A MEMS electromagnetic pump is developed that operates in-plane, using electromagnetic actuation to generate sufficient pumping force and displacement, allowing for the passage of particles up to 15 μm, and is fabricated using surface micromachining techniques, enabling the delivery of small volumes of fluids and particulate matter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric materials are used to generate pumping force, then the pump can achieve precise fluid pumping, but the actuation voltage becomes excessively high and the resonant frequency becomes low
Solution Approach 1:
The patent replaces the piezoelectric actuation system with an electromagnetic actuation system. The electromagnetic pump uses coil windings and permanent magnets to generate the pumping force, eliminating the need for high-voltage piezoelectric materials. This substitution maintains precise fluid pumping capability while significantly reducing the actuation voltage requirement and enabling higher resonant frequency operation.
2Volume of moving object
If vertical pump structure is used, then the pump can achieve compact design, but the fabrication becomes complex and expensive
Solution Approach 1:
The patent inverts the conventional vertical pump structure by implementing an in-plane pump design. Instead of moving the pumping element perpendicular to the substrate, the pumping action occurs within the plane of the substrate. This inversion simplifies the fabrication process by eliminating complex vertical interlocking structures and allows for easier integration with microfluidic channels, while still achieving compact packaging.
Solution Approach 2:
The patent transitions from vertical (3D) pumping motion to in-plane (2D) pumping motion. By changing the dimension of the pumping action to occur within the substrate plane rather than perpendicular to it, the design achieves compactness while simplifying manufacturing. The in-plane motion allows for straightforward integration with planar microfluidic channels and avoids the fabrication complexities of vertical valve structures.
3Reliability
If complex valve structures are used, then the pump can achieve reliable fluid control, but the manufacturing cost increases
Solution Approach 1:
The patent employs passive valve structures that automatically open and close based on pressure differentials generated during the pumping cycle. The valves utilize the natural pressure changes created by the pumping element's motion to control fluid flow, eliminating the need for complex active valve mechanisms with motors or solenoids. This self-service approach maintains reliable fluid control while significantly reducing manufacturing complexity and cost.
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 in-plane electromagnetic MEMS pump achieves a pumping force of at least 3 mN and 0.5 nl displacement, capable of delivering 60 μL/min of fluid, including particle-based drugs, and is inexpensive and easy to fabricate, suitable for drug delivery systems like insulin administration in diabetic patients.
Implementation Method 1
The actuation mechanism may be electromagnetic, wherein magnetic flux generated by a flux-generating mechanism which interacts with a magnetically permeable member. This interaction may retract a pumping element such as a piston or diaphragm.
Implementation Method 2
When the circuit is energized, magnetic flux circulating in the circuit jumps across the gap, interacting with the permeable member and drawing it further into the gap.
Data Source
AI summary
A micromechanical pumping system is formed on a substrate surface. The pumping system uses a pumping element which pumps a fluid through valves which move in a plane substantially parallel to the substrate surface. An electromagnetic actuating mechanism may also be fabricated on the surface of the substrate. Magnetic flux produced by a coil around a permeable core may be coupled to a permeable member affixed to a pumping element. The permeable member and pumping element may be configured to move in a plane parallel to the substrate. The electromagnetic actuating mechanism gives the pumping system a large throw and substantial force, such that the fluid pumped by the pumping system may be pumped through a transdermal cannula to deliver a therapeutic substance to the tissue underlying the skin of a patient.