Single-Port SAW Resonator Sensor for Liquid Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing surface acoustic wave (SAW) biosensors face significant signal loss and sensitivity issues when immersed in liquids due to damping and short-circuiting effects, limiting their effectiveness in chemical and biological sensing applications.
Innovation Solution
A single-port SAW resonator sensor design featuring an interdigital transducer (IDT) separated acoustically and electrically from the sample region, utilizing reflective gratings to confine the sample and reduce signal loss, with a fluidic layer preventing sample ingress to the IDT, allowing for reliable measurement of liquid and conductive samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If SAW transducers are placed close to each other for lower-loss transmission, then transmission loss is reduced, but the transducers become susceptible to short-circuiting effect from electrically conductive liquid
Solution Approach 1:
A protective layer is introduced as an intermediary between the SAW transducers and the liquid sample. This layer acts as a barrier that prevents direct electrical contact between the conductive liquid and the transducer electrodes, thereby eliminating the short-circuiting risk while allowing the transducers to remain in close proximity for efficient acoustic wave transmission.
2Productivity
If the delay path between SAW transducers is extended, then more measurement points are available, but SH-SAW damping in the liquid substrate increases causing stronger signal loss
Solution Approach 1:
The patent uses a resonant cavity structure that creates standing waves with multiple nodes and antinodes along the acoustic path. This allows multiple measurement points to be obtained from a single resonant structure, effectively providing multiple measurement locations without extending the physical delay path, thereby avoiding increased damping and signal loss.
3Adaptability or versatility
If the sensor is fully immersed in liquid for sensing, then liquid phase sensing is enabled, but transmission losses increase significantly
Solution Approach 1:
The sensor structure is segmented into distinct functional zones: a protected transducer region where the IDTs are enclosed and isolated from the liquid, and an exposed sensing region where the resonant cavity interacts with the liquid sample. This segmentation allows the sensor to be immersed in liquid for sensing while the transducers remain protected, maintaining low transmission loss.
4Measurement precision
If IDT is made mass sensitive to the sample, then direct mass detection is achieved, but the IDT becomes susceptible to damping and short-circuiting effects
Solution Approach 1:
The resonant cavity serves as an intermediary that couples the IDT to the liquid sample. The IDT generates acoustic waves that resonate in the cavity, and the liquid sample interacts with this resonant field. This indirect coupling mechanism allows mass detection through changes in resonant frequency while preventing direct contact between the IDT and the liquid, thereby avoiding damping and short-circuiting effects.
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 design achieves reduced signal loss and increased energy confinement near the sample, enhancing mass sensitivity and reducing temperature variations, enabling efficient sensing of various samples, including viscous and conductive liquids, with improved sensitivity and robustness.
Implementation Method 1
A first input SAW transducer excites SAWs
Implementation Method 2
at least one reflective grating
Implementation Method 3
Surface acoustic wave resonant sensor
Data Source
AI summary
A surface acoustic wave resonant sensor for measuring a sample comprising a single port surface acoustic wave (SAW) resonator comprising an interdigital transducer and at least one reflective grating. The sensor is provided with a region for receiving the sample, said region being in communication with the at least one reflective grating and the IDT is separated acoustically and electrically from the region for receiving a sample such that the IDT is not mass sensitive to the sample. The sensor is especially suitable for bio sensing applications.