Methods and apparatus for interfacing sensors with fluid materials
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Publication Number
US-11499942-B2
Publication Date
2022-11-15
Expiration Date
Abstract
Various liquid cells for use in surface acoustic wave-based sensors are disclosed. The sensor can include a substrate, at least one sensor element, and at least one pair of electrical components. The electrical components can be located on opposite ends of the sensor element. The liquid cell can include a top layer that is configured to cover at least a portion of the pair of electrical components. The liquid cell can also include a fluidic channel. The fluidic channel can be configured to receive a liquid media and is arranged not intersect with any of the pair of electrical components. The liquid cell can also include a plurality of peripheral walls that are configured to form a plurality of air pockets. Each of the plurality of air pockets are configured to form virtual non-physical walls to prevent the liquid media from contacting the at least one sensor element.
Core Innovation
The invention relates to surface acoustic wave (SAW) sensors and the isolation of electrical components from fluid media using an air-pocket air-liquid virtual wall. A SAW sensor includes a substrate with at least one sensor unit that has a sensor element, a pair of electrical components located on opposite ends of the sensor element, and a first and a second peripheral wall disposed on the substrate. The fluidic channel extends over a portion of the sensor element, and a top layer is disposed over the peripheral walls to create an air pocket over each electrical component when a fluid is present in the fluid channel.
Each air pocket is bounded by the top layer, the respective peripheral wall, and the fluid, such that the air pocket forms a virtual wall at an air-liquid interface above the electrical components. This arrangement isolates liquid media from the electrical components without the need for a physical acoustic-wave-path wall. The document further describes that a virtual-wall air-pocket pressure-balance model includes a critical pressure difference at the interface and that liquid pressure can be controlled using volumetric flow rate.
The sensor unit can include analyte-capture functionality by configuring the sensor element surface to capture at least one analyte. The document also describes applications in biochemical and biomedical diagnostics in liquid media for detecting pathogens, proteins, and nucleic acids, and includes an example sensing context such as tear salt concentration.
Claims Coverage
The document includes two independent claims directed to a SAW sensor structure with peripheral walls and a top layer that creates bounded air pockets over electrical components, and a method for isolating a SAW sensor electrical component from fluid media using the same structural elements. Across the independent claims, the inventive features are centered on creating an air-pocket virtual wall bounded by a top layer, peripheral walls, and the fluid, including refinements that specify virtual-wall definition by pressure difference and control via volumetric flow rate.
Air pockets bounded by top layer, peripheral walls, and fluid over electrical components
A surface acoustic wave sensor having a substrate with at least one sensor unit, a sensor element, and a pair of electrical components on opposite ends of the sensor element, with a first peripheral wall and a second peripheral wall disposed on the substrate around three sides of respective electrical components and around at least a portion of the sensor element proximate the electrical components; a fluidic channel extending over a portion of the sensor element; and a top layer disposed over the first peripheral wall and the second peripheral wall, thereby creating an air pocket over each electrical component when a fluid is present in the fluid channel, where the air pocket is bounded by the top layer, the respective peripheral wall, and the fluid.
Isolating SAW electrical component from fluid using peripheral walls and top-layer air pocket
A method of isolating an electrical component of a surface acoustic wave sensor from a fluid media by providing a first peripheral wall and a second peripheral wall extending around three sides of respective electrical components and around at least a portion of the SAW sensor proximate the electrical components; providing a fluid channel on the substrate; and providing a top layer on top of the first peripheral wall and the second peripheral wall to create an air pocket over the electrical component when a fluid is present in the fluid channel, where the air pocket is bounded by the top layer, the respective peripheral wall, and the fluid.
Virtual wall defined by pressure difference at the liquid-air interface
The method in which a virtual wall at an interface of the liquid media and the air pocket is defined by a pressure difference between the liquid media and the air pocket.
Control of liquid pressure by adjusting volumetric flow rate
The method including adjusting a volumetric flow rate of the fluid to control liquid pressure of the liquid media.
Claim coverage focuses on an air-pocket structure formed over SAW electrical components by peripheral walls and a top layer, where the air pocket is bounded by the top layer, the peripheral wall, and the fluid. It further covers a method of isolating the electrical component from fluid media using the same concept, with dependent refinements defining the virtual wall by pressure difference and controlling liquid pressure via volumetric flow rate.
Stated Advantages
Isolates liquid media from the electrical components without requiring a physical acoustic-wave-path wall over the sensor element.
Documented Applications
Biochemical/biomedical diagnostics in liquid media for detecting pathogens, proteins, and nucleic acids.
Sensing tear salt concentration in dry eyes.
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