Test card for assay and method of manufacturing same
Inventors
Revilla, Ryan Alan • Heltsley, Roy James • Lee, Steve Hoe • Patel, Tej Rushikesh
Assignees
Publication Number
US-10214772-B2
Publication Date
2019-02-26
Expiration Date
2036-06-17
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Abstract
A disposable test card configured to accept a fluid sample for an assay, and a method of manufacturing same, is disclosed herein. In a general example embodiment, a test card for analyzing a fluid sample includes a first substrate layer including an inlet port and an outlet port, a channel layer bonded to the first substrate layer, the channel layer including a microchannel placing the inlet port in fluid communication with the outlet port, and a second substrate layer bonded to the channel layer, the second substrate layer having electrodes printed adjacent to a target zone of the microchannel of the channel layer, wherein the electrodes are configured to raise the temperature of the fluid sample within the target zone of the microchannel when a current is applied thereto.
Core Innovation
The present disclosure relates to a disposable test card configured to accept a fluid sample for an assay and a method of manufacturing the test card. The test card is designed to include a first substrate layer with an inlet port and an outlet port, a channel layer bonded to the first substrate layer comprising a microchannel that fluidically connects the inlet port and the outlet port, and a second substrate layer bonded to the channel layer which carries electrodes printed adjacent to a target zone of the microchannel. These electrodes, when energized by a current, heat the fluid sample within the target zone, facilitating reactions such as PCR.
The invention addresses the need for a low-cost, disposable, and easy-to-use test card platform that can operate in point-of-care (POC) diagnostic settings with minimal user training. Current POC immunoassays suffer from limited sensitivity and specificity particularly early in infections, while nucleic acid amplification tests (NAATs) have superior sensitivity and specificity but traditionally require complex equipment and processes. The disclosed test card aims to combine the high analytical performance of NAATs with simplified, microfluidic-based sample handling and heating capabilities to permit rapid, sensitive assays like PCR with minimal complexity.
Claims Coverage
The patent includes one independent method claim describing the manufacturing process of the test card with several associated inventive features.
Method of manufacturing a test card with layered polymer substrates and printed conductive circuitry
The method involves cutting a microchannel into a first polymer material to form a channel layer, cutting first and second apertures into a second polymer material to form a first substrate layer, bonding these layers along with a second substrate layer to form a single bonded layer with fluid communication between apertures, forming a third substrate layer thicker than the first two, printing conductive ink onto the bonded layer, and adhering the third substrate layer on the opposite side of the bonded layer to form the test card with conductive ink exposed for electrical contact.
Use of diffusion bonding in layer assembly
The method includes diffusion bonding the first substrate layer to the first side of the channel layer and bonding the second substrate layer to the second side of the channel layer.
Inclusion of surfactant coating inside microchannels
The method includes filling the microchannel with a surfactant solution to improve wettability and prevent bubble formation, optionally using a water-containing surfactant solution and allowing the water to evaporate, leaving surfactant molecules on the microchannel surface.
Customized aperture design in the third substrate layer
The third substrate layer is cut with multiple apertures aligned with the first and second apertures, including inlet and outlet ports as well as a mixing chamber formed by differing cross-sectional areas in the apertures, with alignment precisely controlled during adhesion.
Formation and alignment of an analysis port aperture
An analysis port aperture is cut into the third substrate layer and aligned with a target zone of the microchannel and electrodes formed by the conductive ink, with the electrodes positioned within the borders of the analysis port aperture.
Application of dielectric ink over conductive ink
The method includes printing a dielectric ink layer over at least part of the conductive ink on the bonded layer's first side to serve as a protective, non-conductive coating.
Strategic electrical contact placement
Electrical contacts formed by the conductive ink are exposed for contact with external current sources and are positioned outside the borders of the analysis port aperture to allow electrical connection without interference with the reaction observation.
These inventive features collectively define a manufacturing method for a disposable test card integrating microfluidic channel layers, precisely cut apertures, surfactant-treated microchannels, printed conductive and dielectric inks forming heating electrodes and sensors, and structural layers designed to facilitate fluid handling, thermal control, and sample analysis in point-of-care nucleic acid assays.
Stated Advantages
Enables rapid, high sensitivity and specificity diagnostic assays with minimized complexity suitable for low-resource and point-of-care settings.
Allows for effective mixing of fluid samples and reagents in a low-volume format reducing reagent costs.
Thinning at the target zone and the use of an analysis port permits rapid thermal cycling crucial for fast PCR reactions.
Surfactant coating improves fluid loading and prevents bubble formation during thermal cycling.
Structurally robust design with thicker top substrate provides rigidity and facilitates integration with external devices.
The screen printed electrodes provide integrated means to heat the sample and detect fluid presence or chemical changes in the microchannel.
Documented Applications
Point-of-care in vitro diagnostic assays, specifically nucleic acid amplification tests such as PCR for infectious agents.
Analysis of small volume biological fluids including whole blood, serum, urine, saliva, tears, and similar samples.
Rapid detection and diagnosis of infectious diseases early in infection stages where nucleic acid detection offers superior sensitivity to immunoassays.
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