Infectious disease diagnosis in point-of-care settings can be greatly improved through integrated, automated nucleic acid testing devices. We have developed an early prototype for a low-cost system which executes isothermal DNA amplification coupled to nucleic acid lateral flow (NALF) detection in a mesofluidic cartridge attached to a portable instrument. Fluid handling inside the cartridge is facilitated through one-way passive valves, flexible pouches, and electrolysis-driven pumps, which promotes a compact and inexpensive instrument design. The closed-system disposable prevents workspace amplicon contamination. The cartridge design is based on standard scalable manufacturing techniques such as injection molding. Nucleic acid amplification occurs in a two-layer pouch that enables efficient heat transfer. We have demonstrated as proof of principle the amplification and detection of Mycobacterium tuberculosis (M.tb) genomic DNA in the cartridge, using either Loop Mediated Amplification (LAMP) or the Exponential Amplification Reaction (EXPAR), both coupled to NALF detection. We envision that a refined version of this cartridge, including upstream sample preparation coupled to amplification and detection, will enable fully-automated sample-in to answer-out infectious disease diagnosis in primary care settings of low-resource countries with high disease burden.
We present a passive, miniature check valve which can be manufactured using standard techniques ideal for low-cost, disposable systems used in medical devices and other applications. The body of the valve consists of a hollow cylindrical core, closed at one end, with a side port and a cylindrical elastomeric sleeve placed over the core body, covering the side port. The pressure required for initial opening of the valve, referred to as cracking pressure, can be adjusted, and depends predominantly on the valve core outer diameter, the sleeve inner diameter, the sleeve wall thickness, and the sleeve material’s modulus of elasticity. These parameters can be controlled to tight tolerances, while the tolerances on other features can be relaxed, which simplifies valve manufacturing and assembly. Valve embodiments produced from different materials, and with varying critical dimensions, exhibited distinct and reproducible cracking pressures in the range of 2 to 20 PSI. The cracking pressure did not vary significantly as a function of flow rate. No back flow leakage was encountered up to 30 PSI, the pressure limit of the sensor used in this experiment. Most of the valves tested had small internal volumes of 3–4 μL. The internal volume can be further reduced by selecting a core of smaller inner diameter. In contrast to lithography-based microvalves that generally must be manufactured in-situ within the fluidic device, the herein presented valve can be manufactured independently of, and can be readily integrated into fluidic systems manufactured via a wide selection of fabrication methods.
No abstract
Technologies that enable infectious diseases diagnosis in low-resource settings could greatly facilitate effective treatment and containment of such diseases. Nucleic acid amplification testing can be used to identify pathogens, but typically requires highlytrained personnel and large, expensive lab equipment, neither of which is available in low-resource settings. Our overall goal is to develop a portable diagnostic system that utilizes a low-cost, disposable, mesofluidic cartridge and a handheld electronics unit to perform fully-integrated nucleic acid testing at the point of care in low-resource settings.As a first step toward this goal, we developed a subunit to execute isothermal nucleic acid amplification coupled with lateral flow detection, in parallel with the development of a sample preparation subunit by our collaborators at Claremont BioSolutions. Fluid handling inside the amplification and detection cartridge is facilitated through one-way passive valves, flexible pouches, and electrolysis-driven pumps, which promotes a compact and inexpensive instrument design. The closed-system disposable prevents workspace amplicon contamination. The cartridge design is based on standard, scalable manufacturing techniques, such as injection molding. Using an initial prototype system, we demonstrated detection of purified Mycobacterium tuberculosis genomic DNA. We then developed a refined amplification and detection cartridge in conjunction with an improved portable instrument, which automates pumping, heating, and timing, using a design format compatible with eventual integration with the sample preparation subunit.This refined cartridge incorporates a novel, inexpensive, stand-alone, passive valve, smaller, integrated pump components, a more complex injection molded polycarbonate cartridge core piece, and enhanced lateral flow chambers to improve visual detection. The independent valve component can be tailored for a variety of fluidic systems. We demonstrated appropriate fluidic and thermal control, and successful isothermal nucleic acid amplification within this refined amplification and detection subunit. We have developed a separate fluidic module for master-mix reagent storage and reconstitution that is designed to act as the interface between the amplification and detection subunit and the upstream sample preparation subunit. We envision that the merger of these two subunits into a fully-integrated cartridge will enable user-friendly, automated sample-in to answer-out diagnosis of infectious diseases in primary care settings of low-resource countries with high disease burden.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.