Fluidic-Channel MEMS Actuator for Sealed Pneumatic Force
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Solution Overview
Problem
Existing MEMS actuators, particularly piezoelectric and micro-pneumatic types, suffer from limited actuation force and mechanical reliability issues due to air leaks and exposure to external objects, which hinder their performance in various applications.
Innovation Solution
A MEMS actuator with a strainable structure that expands when fluid is pumped, featuring a pneumatically controllable semiconductor body with a strainable structure that elastically strains along a transverse axis, exerting an actuation force on an external body, and a manufacturing process using MEMS technology to integrate piezoelectric valves and micro-pumps for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If piezoelectric micro-actuators are used to generate displacement, then the actuator can convert electrical quantity to mechanical quantity, but the actuation force is limited to 10-100 mN which is insufficient for many applications
Solution Approach 1:
The patent combines multiple piezoelectric actuators (typically three or more) arranged in a specific geometric configuration to work together and generate amplified actuation forces, transforming the limited output of individual actuators into sufficient force for practical applications
Solution Approach 2:
The patent transitions from one-dimensional linear piezoelectric actuators to multi-dimensional arrangements (such as radial or triangular configurations), where the combined effect of multiple actuators working in different directions produces significantly higher net force and moment output
2Ease of manufacture
If a Pyrex-silicon-Pyrex structure is used for micro-pneumatic actuators, then the structure can be assembled by anodic bonding, but air leakages occur across the Pyrex-silicon interfaces that decrease actuation performances
Solution Approach 1:
The patent uses uniform silicon-based materials throughout the structure, eliminating the heterogeneous Pyrex-silicon-Pyrex interfaces that cause leakage. This homogeneous silicon construction maintains manufacturing simplicity while achieving complete air tightness
Solution Approach 2:
The patent employs silicon-silicon composite structures with integrated membranes and chambers, creating a monolithic sealed system that prevents air leakage while maintaining the ease of fabrication through standard silicon processing techniques
3Ease of operation
If the deformable structure totally extends over the semiconductor substrate, then the actuator can achieve full range of motion, but the structure is exposed to bumps with external objects reducing mechanical reliability
Solution Approach 1:
The patent divides the deformable structure into segmented regions with controlled flexibility zones, allowing motion in specific directions while providing structural reinforcement in areas susceptible to damage from external impacts
Solution Approach 2:
The patent employs carefully designed thin film membranes with controlled thickness and material properties that provide sufficient flexibility for full range of motion while maintaining adequate mechanical strength to resist damage from external bumps and impacts
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 actuator achieves enhanced actuation force and improved mechanical reliability by leveraging a strainable structure that expands to exert force externally while maintaining a sealed internal environment, addressing the limitations of previous designs.
Implementation Method 1
a strainable structure (20) of semiconductor material formed in the semiconductor body (12)... which is controllable to strain elastically
Implementation Method 2
MEMS actuators of piezoelectric type are known, which generate displacements following strains of the same caused by electric fields applied thereto
Implementation Method 3
which allows a fluid to be pumped therewithin, generating a consequent strain of the strainable structure (20)
Data Source
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AI summary
MEMS actuator (10) comprising: a semiconductor body (12) with a first surface (12a), defining a housing cavity (22) facing the first surface (12a) and having a bottom surface (22a), the semiconductor body (12) further defining a fluidic channel (25) in the semiconductor body (12) with a first end (25') across the bottom surface (22a); and a strainable structure (20) which extends into the housing cavity (22), is coupled to the semiconductor body (12) at the bottom surface (22a), and defines an internal space (24) facing the first end (25') of the fluidic channel (25) and comprising at least a first and a second internal subspace (26', 26") connected to each other and to the fluidic channel (25). When a fluid is pumped through the fluidic channel (25) into the internal space (24), the first and second internal subspaces (26', 26") expand straining the strainable structure (20) along the first axis (Z) and generating an actuation force (Fatt) exerted by the strainable structure (20) along the first axis (Z), in the opposite direction with respect to the housing cavity (22).