Research

Patterned paper has emerged as a popular substrate for the development of point-of-care diagnostic devices since it was first introduced almost a decade ago. Compared to traditional lateral flow assays like the pregnancy strip, patterned paper devices are advantageous because they can be used for (i) detecting multiple targets on a single device, e.g. micro paper analytical devices (microPADs) or (ii) conducting highly sensitive signal-amplified assays, e.g. two-dimensional paper networks (2DPNs). In order to conduct complex multi-step chemical assays, innovative paper networks have been designed to program the movement of fluids. For developing these paper-based devices, my work includes understanding the field of modelling flow through paper by coupling the Richards equation with the species transport equation enabling tracking the movement of multiple reagents in various paper-network devices.

Detection of some life-threatening diseases such as cancer at an early stage could facilitate successful remediation, and this is possible with the use of efficient biosensors. A class of such biosensors are the heterogeneous immunosensors where the capture of the target antigen molecules occur by two important and sequential events i.e., the transport of antigens from the bulk solution to the sensor surface, and binding reaction of the antigens with the surface immobilized antibodies. An efficient immunosensor must achieve high capture efficiency in the least possible time. Higher capture efficiencies in these heterogeneous immunosensors have been achieved by adopting several strategies which can be broadly classified as the surface engineering, process engineering, and/or optimization of the sensor geometry.

The isolation and analysis of blood-based biomarkers hold promising potential towards classifications and detection of various diseases such as cancer. However, the rarity of the presence of these molecules in the blood stream demands for design of an efficient device for the same. In this context, label-free isolation techniques, with the use of inertial microfluidic devices can be exploited, wherein the flow is at an intermediate Reynold’s number between the Stokes regime and turbulent regime and thus having finite effects of both inertia and viscosity of the fluid. Here the shape of the microfluidic channel plays an important role. For example, inertial forces acting on a spiral or serpentine channels, can be designed with lesser instrumentation for the isolation of Circulating Tumor Cells (CTCs) through inertial migration in a label-free manner, suitable for developing point-of-care devices.