Publication: Design and Development of Disposable Microsystems for Sensing Applications
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Date
2025-04-28
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Indian Institute of Technology, Jodhpur
Abstract
Sensing and diagnostics have become essential parts for our healthcare monitoring. Disposable microsystems can be potential solution for the same which are designed for single-use while eliminating the risk of cross-contamination between patients. These devices are typically aimed to design for straightforward, one-time use, simplifying the testing process and hence, are of low initial cost. Along with this, it addresses environmental concerns associated with single-use plastics. In this context, Paper-based analytical devices (PADs) are desgined and developed which are economical, recyclable, biocompatible, and robust. They consist of a network of hydrophobic and hydrophilic micro-channels which are capable to handle and quantitatively analyze the target analyte. There is no requirement for the clean-room facility to fabricate such device, and it does not require any external pump for the movement of target analytes. Paper strips have been used for several decades for biomedical assays because they provide a low-cost platform for colorimetric testing. Previously, Müller and Clegg reported the first kind of paper- based microfluidic device in 1949. However, the Whitesides group later explored paper-based microfluidics, and it opened new pathways in this field for the use of paper to develop portable, on-site detection in bio-sensing applications. This research investigates simple fabrication strategies for cost-effective mass manufacturing of disposable microsystems for sensing applications, while utilizing a leak-proof paper-based analytical device (PAD) by creating a hydrophobic zone through the proper penetration of ink into the pores of the paper. An inexpensive disposable colorimetric sensor developed through the assistance of chemometric reaction and tested for the optimization of samples and the determination of glucose for different concentrations (0.5-20 mM and 0.1-0.5 M) with a LOD of 2.92 mML−1. To increase platform's resistance to variations in illumination and camera optics, images taken with several cellphones in various lighting conditions were used to train classifiers, with an accuracy of 72.7%. To enhance the analysis platform’s robustness and make it user-friendly, the image data set was taken at various angles of incident light with an overall accuracy of~ 93%. Further, for the multiplexed detection of the analyte, a unique trident-shaped µPAD has been fabricated on a chemically modified A4 paper, followed by the theoretical and experimental fluid flow. Three different biomarkers, glucose, lactate, and uric acid, were detected through colorimetric enzymatic reaction on the novel trident-shaped disposable PAD, with LOD and coefficient of determination of 0.28 mM, and 0.98, 0.40 mM and 0.97, and 0.22 mM and 0.99) respectively. This platform achieves a high accuracy rate of analyte detection (~ 97%) in predicting three different colorimetric findings, both quantitatively and qualitatively through an Android application. The application's integrated image processing tools autonomously identify the region of interest (ROI) and minimize human error, enhancing the platform’s user- friendliness and precision. Proceeding the work, for the exploration of electrochemical sensing, a non-enzymatic electrochemical sensor was developed for the detection of lactic acid with a sensitivity of 0.00176 mA*µM-1cm-2 and LOD of 0.76 mM, followed by computation studies of reaction molecules.
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Kishnani, Vinay(2020).Design and Development of Disposable Microsystems for Sensing Applications (Doctor's thesis). Indian Institute of Technology Jodhpur