A Rapid One-Step Microfluidic Fabrication Approach for Multiple Through-Hole Generation Enabling Spatial Transcriptomic Analyses

With the development of complex microfluidic systems, biomedical field has witnessed a revolutionary change in the way biological analyses are performed that are otherwise unattainable using conventional laboratory methods. Polydimethylsiloxane (PDMS) based microfluidic chips have enabled high parallelization, i.e. testing thousands of samples simultaneously, allowing researchers to make sound decisions in a single run. For example, spatial transcriptomic data that plays a vital role in cancer research and developmental biology can now be retained by microfluidic devices that are capable of delivering barcoded DNA tags to a tissue sample. However, reservoirs used for storing the DNA barcodes are fabricated by manually punching through the PDMS layer. There is no current method that allows us to create multiple of these through holes simultaneously. Manual punching is unreliable because not only is it time consuming but also requires skilled personnel to create those through-holes without leaving any PDMS debris inside the microchannels. This gives rise to a need for an easy interface fabrication method so that researchers take advantage of microfluidic systems and continue to explore high resolution spatial transcriptomic data through increased number of holes. Hence, my research focusses on exploring a fabrication approach to create multiple through-holes in PDMS. To do that, I have explored the utilisation of a vulcanizer. The parameters that greatly influence the fabrication of through-holes such as PDMS degassing and curing times, curing temperature and the amount of weight that needs to be exerted on the PDMS layer during the curing process were optimized to a certain value to produce repeatability. The advantages that the one-step through-hole fabrication method possesses in comparison to manual punching technique was studied. The validity of the approach was tested by creating a microfluidic device involving 100 number of reservoirs and applying it to the context of spatial transcriptomics. I checked the proper delivery of barcodes using the microfluidic design using fluorescent labels. This signifies that further binding of DNA barcodes to the tissue sample can be achieved and researchers can make use of spatial transcriptomics to its full potential by increasing through-holes.