Laser direct-write technique for rapid multiplexed detection on lateral-flow devices

Paper-based lateral flow devices (LFD) that allow rapid non-quantitative detection of a single analyte in a fluidic sample, within a time-span of 5-30 minutes are regarded as ideal diagnostic solutions for point-of-care (POC) scenarios, especially for the under-resourced settings of developing countries with remote poorly accessible regions. In recent years, there has been an increasing need for performing multiplexed diagnostics at the POC for rapid and simultaneous detection of multiple analytes within a single sample. Currently, only a few commercial LFDs provide such multiplexing either by laminating together different individual LFDs or alternatively, by multiplexing within a single flow-path. Such devices have critically- inherent drawbacks such as, for the former, increased device dimensions and therefore need for larger sample volumes, and for the latter, an undesired interference between different detection sites, i.e. the influence of each of the previous test-lines on subsequent lines positioned further along the flow-path.Herein, to overcome both these limitations, we propose a novel solution – a multi-path LFD (Fig.1) created via the precise partition of the flow-path of a single LFD using our previously reported, proprietary laser direct-write (LDW) technique. The multiple flow-paths allow individual detection of the different analytes in each of the separated channels. Fig.1a shows the schematic of an example three-channel LFD that can be used for simultaneous detection of three different analytes within the same sample. The appearance of coloured test lines in individual channels indicates the presence of the different analytes. Fig.1b shows the use of this three-channel LFD for multiplexed detection of a biomarker panel comprising C-reactive protein, Serum amyloid A-1 and Procalcitonin, used for the diagnosis of bacterial infections.In conclusion, we demonstrate the use of our LDW technique for the creation of multiple flow-paths within a ‘single’ LFD, which allows multiplexed detection, and thereby a hugely improved detection-efficiency