A handheld point-of-care genomic diagnostic system.

The rapid detection and identification of infectious disease pathogens is a critical need for healthcare in both developed and developing countries. As we gain more insight into the genomic basis of pathogen infectivity and drug resistance, point-of-care nucleic acid testing will likely become an important tool for global health. In this paper, we present an inexpensive, handheld, battery-powered instrument designed to enable pathogen genotyping in the developing world. Our Microfluidic Biomolecular Amplification Reader (µBAR) represents the convergence of molecular biology, microfluidics, optics, and electronics technology. The µBAR is capable of carrying out isothermal nucleic acid amplification assays with real-time fluorescence readout at a fraction of the cost of conventional benchtop thermocyclers. Additionally, the µBAR features cell phone data connectivity and GPS sample geotagging which can enable epidemiological surveying and remote healthcare delivery. The µBAR controls assay temperature through an integrated resistive heater and monitors real-time fluorescence signals from 60 individual reaction chambers using LEDs and phototransistors. Assays are carried out on PDMS disposable microfluidic cartridges which require no external power for sample loading. We characterize the fluorescence detection limits, heater uniformity, and battery life of the instrument. As a proof-of-principle, we demonstrate the detection of the HIV-1 integrase gene with the µBAR using the Loop-Mediated Isothermal Amplification (LAMP) assay. Although we focus on the detection of purified DNA here, LAMP has previously been demonstrated with a range of clinical samples, and our eventual goal is to develop a microfluidic device which includes on-chip sample preparation from raw samples. The µBAR is based entirely around open source hardware and software, and in the accompanying online supplement we present a full set of schematics, bill of materials, PCB layouts, CAD drawings, and source code for the µBAR instrument with the goal of spurring further innovation toward low-cost genetic diagnostics.

A point-of-care instrument for rapid multiplexed pathogen genotyping.

We are leveraging recent advances in rapid nucleic acid amplification chemistries, self-powered microfluidics, and low-cost optoelectronics to develop instrumentation for pathogen genotyping in the developing world. A growing number of correlations are emerging between genetic mutations in pathogens and their infectivity, origin, and drug resistance. Particularly for diseases like tuberculosis, where multi-drug resistance is a growing concern, a rapid diagnostic which could inform prescription decisions for newly diagnosed patients would not only save lives and reduce prolonged sickness but would help slow the emergence of more virulent strains. Additionally, for pathogens such as HIV, there is a need for new assay formats which can inexpensively and quantitativly monitor pathogen load. We have developed a portable instrument which uses disposable microfluidic assay cartridges pre-loaded with lyophilized reagents for genetic amplification of multiple markers. The cartridges can be adapted for a variety of sample types (blood, sputum, saliva). The instrument controls assay temperature and quantitatively monitors real-time fluorescence signals from 96 individual reaction chambers. The platform can be tailored for different economic situations--from a quantitative electronic readout to a simple binary readout with the naked eye.