Inductive Micro Tactile Sensor Structure Without MEMS Stiction
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Solution Overview
Problem
Micro tactility-simulating sensing devices produced using MEMS technology face issues such as stiction, residual stress, low yield, and custom-made manufacturing processes, which affect their reliability and integration into systems.
Innovation Solution
A micro tactility-simulating sensing device is developed using an inductive coil produced through standard integrated circuit processes, eliminating suspended movable elements and incorporating a polymer molding technology for enhanced signal reading and mass production capabilities, allowing for dual-coil measurement and various force range sensing without custom manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MEMS technology with suspended thin film structures is used for sensing, then the device can achieve micro-scale sensing capability, but the sensing structures are damaged under larger load and stiction problem appears
Solution Approach 1:
The patent replaces the mechanical suspended thin film structure with an inductive sensing structure consisting of a rigid substrate, magnetic layer, and inductive coil. The tactile load is converted to magnetic flux changes rather than mechanical displacement, eliminating the stiction and structural damage problems inherent in MEMS suspended films while maintaining micro-scale sensing capability
Solution Approach 2:
The patent employs a composite structure combining rigid substrate material, magnetic layer material, and inductive coil material. This composite approach provides both mechanical robustness for larger loads and the necessary magnetic sensing properties, resolving the contradiction between structural integrity and sensing functionality
2Ease of manufacture
If MEMS technology is used with sacrificial layer removal, then the suspended thin film can be formed, but the stiction problem appears due to Van der Waals force
Solution Approach 1:
The patent extracts and eliminates the sacrificial layer entirely from the manufacturing process. Instead of forming a suspended structure that requires sacrificial layer removal, the design uses a rigid substrate that maintains structural integrity without needing any sacrificial layer, thereby preventing stiction problems from occurring
Solution Approach 2:
The patent creates a functional copy of the suspended membrane sensing capability using electromagnetic induction rather than physical suspension. The inductive coil and magnetic layer replicate the sensing function of suspended films without the mechanical vulnerabilities, achieving the same sensing purpose through a different physical mechanism
3Volume of moving object
If standard integrated circuit process is used for inductive coil production, then the sensing coil size is reduced to within 1 mm, but the inductance needs to be increased to enhance the signal
Solution Approach 1:
The patent uses a composite magnetic circuit structure combining soft magnetic material, magnetic layer, and magnetic flux concentration structures. This composite approach enables high inductance in a compact coil by enhancing magnetic flux density and confinement, allowing standard IC process coils of within 1 mm to achieve sufficient signal strength
Solution Approach 2:
The patent introduces vertical stacking of magnetic layers and multi-layer coil structures to increase inductance without increasing planar footprint. By utilizing the third dimension (vertical stacking), the design achieves high inductance in a compact form factor suitable for standard IC processes
4Productivity
If polymer molding technology is used to integrate sensing interface and chip, then mass production is enabled, but the process complexity increases
Solution Approach 1:
The patent merges the sensing interface, magnetic layer, and chip into a single integrated structure using polymer molding technology. This consolidation enables mass production through standard molding processes while the modular design keeps the integration complexity manageable by combining components that work together synergistically
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 robust, high-yield, and reliable sensing device with improved signal reading and spatial resolution, enabling commercial mass production and integration into smart devices with flexible force range measurement capabilities.
Implementation Method 1
a magnetic rigid body coupled with the first inductor to allow the first inductor to sense a magnetic flux passing therethrough
Implementation Method 2
a polymer configured between the chip and the magnetic rigid body to have a characteristic distance therebetween
Data Source
AI summary
The present invention provides a micro tactility-simulating sensing device, including: a chip including a first top surface and a first inductor, wherein the first top surface has wiring through holes configured to allow an external circuit to connect to the first inductor, and the first top surface is a flat surface except the wiring through holes; a magnetic rigid body coupled with the first inductor to allow the first inductor to sense a magnetic flux passing therethrough, and configured to receive a tactile load; and a polymer configured between the chip and the magnetic rigid body to have a characteristic distance therebetween, wherein the characteristic distance and the magnetic flux have a functional relationship. The micro tactility-simulating sensing device of the present invention can effectively increase the magnitude of the measured signal and provide two different ways to read the signal.