We present a rapid (<10 s), cost-effective, unique single-step method for fabricating paper-based devices without necessitating any expensive instrumentation, simply by deploying correction pens that are otherwise commonly used for masking typos in printed or written matters. The marked regions formed by deposits from the correction pen demonstrate ubiquitous flow resistances to typical aqueous solutions and organic solvents in the transverse direction, resulting in a preferential bulk flow along the axial direction of the paper channels ‘fabricated’ in the process. Considering the simplicity and cost-effectiveness of this platform, it is deemed to be ideal for (bio) chemical sensing and point-of-care diagnostics in resource-limited settings.
We report a simple, affordable (~ 0.02 US $/test), rapid (within 5 minutes) and quantitative paper-based sensor integrated with smartphone application for on-spot detection of hemoglobin (Hgb) concentration using approximately 10µl of finger-pricked blood. Quantitative analytical colorimetry is achieved via android-based application (Sens-Hb); integrating key operational steps of image acquisition, real-time analysis and result dissemination. Further, feedback from machine learning algorithm for adaptation of calibration data offers consistent dynamic improvement for precise predictions of the test results. Our study reveals a successful deployment of the extreme point-of-care (EPOC) test in rural settings where no infrastructural facilities for diagnostics are available. The Hgb test device is validated both in the controlled laboratory environment (n = 200) and on the field experiments (n = 142) executed in four different Indian villages. Validation results are wellcorrelated with the pathological gold standard results (r = 0.9583) with high sensitivity and specificity for healthy (n=136) (>11 g/dL) (specificity: 97.2%), mild anemic (n = 55) (<11 g/dL) (sensitivity: 87.5%, specificity: 100%) and severe anemic (n = 9) (<7 g/d L) (sensitivity: 100%, specificity: 100 %) samples. Results from field trials reveal that only below 5% cases of the results are interpreted erroneously by classifying mild anemic patients as healthy ones. On-field deployment has unveiled the test-kit to be extremely user-friendly that can be handled by minimally trained frontline workers for catering the needs of the under-served communities.
We developed a piecewise isothermal nucleic acid test (PINAT) as a platform technology for diagnosing pathogen-associated infections, empowered by an illustrative novel methodology that embeds an exclusive DNA-mediated specific probing reaction with the backbone of an isothermal reverse transcription cum amplification protocol for detecting viral RNA. In a point-of-care format, this test is executable in a unified single-step, single-chamber procedure, leading to seamless sample-to-result integration in an inexpensive, scalable, pre-programmable, and customizable portable device, with mobile-app-integrated interpretation and analytics involving minimal manually operative procedures. The test exhibited a high sensitivity and specificity of detection when assessed using 200 double-blind patient samples for detecting SARS-CoV-2 infection by the Indian Council of Medical Research (ICMR), and subsequently using 170 double-blind patient samples in a point-of-care format outside controlled laboratory settings as performed by unskilled technicians in an organized clinical trial. We also established its efficacy in detecting Influenza A infection by performing the diagnosis at the point of collection with uncompromised detection rigor. The envisaged trade-off between advanced laboratory-based molecular diagnostic procedures and the elegance of common rapid tests renders the method ideal for deployment in resource-limited settings towards catering the needs of the underserved.
We report a novel piece-wise isothermal nucleic acid test (PINAT) for diagnosing pathogen-associated RNA that embeds an exclusive DNA-mediated specific probing reaction with the backbone of an isothermal reverse-transcription cum amplification protocol as a unified single-step procedure. This single step sample-to-result test method has been seamlessly integrated in an inexpensive, scalable, pre-programmable and portable instrument, resulting in a generic platform technology for detecting nucleic acid from a wide variety of pathogens. The test exhibited high sensitivity and specificity of detection of SARS-CoV-2 infection when assessed using 200 double-blind patient samples, conducted by the Indian Council of Medical Research (ICMR), reporting a positive and negative percent agreement of 94.6% and 98% respectively. We also established its efficacy in detecting Influenza-A virus infection, performing the diagnosis at the point of collection with uncompromised detection rigor. The envisaged trade-off between advanced laboratory-based procedures with the elegance of common rapid tests renders the innovation to be ideal for deployment in resource-limited settings towards catering the needs of the underserved.
We demonstrated an instrument-free miniaturized adaptation of the laboratory gold standard methodology for the direct estimation of plasma glucose from a drop of whole blood using an ultra-low-cost single-user-step paper-strip...
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