V-Groove Shear-Mode Acoustic Sensor for Low-Damping Liquid Sensing
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Solution Overview
Problem
Existing microbalances for physical and chemical sensing in liquid environments, such as SAW and BAW resonators, suffer from dramatic viscous damping, leading to low Q factor and sensitivity, and known shear-mode sensors face challenges in mass production and repeatability.
Innovation Solution
A shear-mode chemical/physical sensor is formed on V-shaped grooves of a [100] crystal orientation Si layer over a substrate, featuring an acoustic resonator with a first metal layer, a thin-film piezoelectric layer, and a second metal layer in an interdigitated pattern, along with a functional layer along the grooves, enhancing sensitivity and Q factor while allowing for customizable sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SAW and BAW resonators are used for sensing in liquid environments, then physical and chemical sensing capability is provided, but viscous damping dramatically reduces Q factor and sensitivity
Solution Approach 1:
The patent changes the operational mode from longitudinal acoustic waves (SAW/BAW) to shear-mode acoustic waves. This parameter change in wave mode fundamentally alters the interaction with liquid, reducing viscous damping effects and improving Q factor and sensitivity for chemical/physical sensing in liquid environments
Solution Approach 2:
The patent employs a composite structure combining piezoelectric material layers with specific crystal orientations and acoustic resonator geometries. This composite approach creates a shear-mode resonator that inherently resists viscous damping while maintaining high sensitivity for detecting analytes in liquid
2Reliability
If tilted-substrate deposition is used to form shear-mode sensors, then Q factor is improved, but mass production and repeatability are hindered
Solution Approach 1:
Instead of tilting the substrate during deposition to create shear-mode sensors, the patent inverts the approach by using standard planar substrate deposition combined with piezoelectric material stacking and acoustic resonator structure design. This reversal enables conventional manufacturing processes while achieving the desired shear-mode operation and high Q factor
Solution Approach 2:
The patent replaces the mechanical tilted-substrate deposition system with a standard planar deposition system combined with layered piezoelectric structure fabrication. This substitution maintains manufacturing simplicity and repeatability while achieving shear-mode sensor performance through material and structural design rather than mechanical substrate orientation
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 shear-mode sensor with improved sensitivity and Q factor in liquid environments, overcoming viscous damping issues and enabling mass production, with customizable sensitivity for various applications.
Implementation Method 1
forming an acoustic resonator over and along the V-shaped grooves, the acoustic resonator including a first metal layer, a thin-film piezoelectric layer, and a second metal layer
Implementation Method 2
A shear-mode chemical/physical sensor is formed on V-shaped grooves of a [100] crystal orientation Si layer over a substrate, featuring an acoustic resonator
Data Source
AI summary
Methods of forming a shear-mode chemical/physical sensor for liquid environment sensing on V-shaped grooves of a [100] crystal orientation Si layer and the resulting devices are provided. Embodiments include forming a set of V-shaped grooves in a [100] Si layer over a substrate; forming an acoustic resonator over and along the V-shaped grooves, the acoustic resonator including a first metal layer, a thin-film piezoelectric layer, and a second metal layer in an IDT pattern or a sheet; and forming at least one functional layer along a slope of the acoustic resonator.