SAW Sensor Protective Film for Lower Acoustic Energy Loss
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Solution Overview
Problem
Conventional sensor apparatuses using surface acoustic wave devices face difficulties in detecting analyte constituents with high sensitivity due to energy losses at the boundary between the piezoelectric substrate and constituent components.
Innovation Solution
A sensor apparatus with a protective film covering the IDT electrodes and immobilization film, reducing energy losses by extending between and contacting with the electrodes and the immobilization film, thereby enhancing detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a surface acoustic wave device is used to detect analyte constituents, then simultaneous detection of multiple characteristics is enabled, but energy losses occur at the boundary between the piezoelectric substrate and constituent components, reducing detection sensitivity
Solution Approach 1:
A protective film is introduced as an intermediary component between the piezoelectric substrate and the IDT electrodes/reaction section. This protective film has acoustic impedance matched to reduce boundary reflections and energy losses, allowing the surface acoustic wave to propagate more efficiently through the device while maintaining the multi-detection capability
Solution Approach 2:
The device employs a composite structure combining the piezoelectric substrate, protective film, IDT electrodes, and reaction section materials. By carefully selecting and combining materials with complementary acoustic and electrical properties, the system achieves both versatile detection functionality and reduced energy loss at material interfaces
2Device complexity
If constituent components are disposed directly on the piezoelectric substrate, then device complexity is reduced, but detection sensitivity deteriorates due to energy losses at the boundary
Solution Approach 1:
The protective film serves as a mediating layer that is acoustically transparent or impedance-matched to the piezoelectric substrate. This allows the simple direct-disposition structure to be maintained while the protective film compensates for boundary energy losses, thus preserving structural simplicity while enhancing detection sensitivity
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 protective film significantly reduces surface-acoustic-wave energy losses, allowing for more sensitive detection of analyte constituents by concentrating energy on the uncovered regions of the immobilization film.
Implementation Method 1
a first IDT electrode configured to generate an acoustic wave which propagates toward the reaction section
Implementation Method 2
a reaction section which undergoes reaction with a component contained in a sample of an analyte liquid, is disposed on a piezoelectric substrate
Implementation Method 3
a second IDT electrode configured to receive the acoustic wave which has passed through the reaction section
Data Source
AI summary
A sensor apparatus includes: an element substrate; a detecting section disposed on an upper surface of the element substrate, the detecting section including a reaction section having an immobilization film to detect an analyte; a first IDT electrode configured to generate an acoustic wave which propagates toward the reaction section, and a second IDT electrode configured to receive the acoustic wave which has passed through the reaction section; and a protective film located on the upper surface of the element substrate so as to cover the first IDT electrode, the second IDT electrode, and at least part of the immobilization film, the protective film extending between and contacting with the immobilization film and at least one of the first IDT electrode and the second IDT electrode.