Application of microfluidics in the study of bilateral sensory neurons of C. elegans and femtolitre-droplet based single-molecule-counting immunoassay for renal graft failure detection

Microfluidics has been instrumental in studying biological process and biomedical applications. This thesis covers application of microfluidics to in-vivo neuroscience and disease diagnostics.
The nematode Caenorhabditis elegans is a leading model system for studying in genetics, development and neurobiology. How one animal takes information of environment and transduces it into one’s behaviour is one of the large questions in the field of neuroscience. With the exception of whole-brain imaging studies, simultaneous imaging studies for one or more pairs of bilateral neurons has been avoided since the animal lies on its left or right side. This limits our understanding of symmetry and asymmetry in sensory response and information flow.
We develop rotatable (PDMS) microfluidic device denoted the side view chip that allows us to image a pair of bilateral neurons in a single focal plane of an epi-fluorescence microscope. We prove the utility of the device by recording the responses of immobilised worms to controlled stimuli, focusing on the responses of two classes of head sensory neurons to changes in NaCl concentration. This can pave the way for researching laterally parallel neurocircuit
Then, we expand the idea to develop another microfluidic device to study how the pair of asymmetric sensory neurons encode the head movement to establish chemotaxis behaviour to NaCl. The device aims to trap the worm with its head allowed to freely move around and treat the gradient of the stimulus from the left to the right of the head of the worm. Reinforced trap for partial immobilisation of the nematode and a module for transposing the flow is developed.
Diagnosing disease in early stage increases effectiveness in treatment. To achieve this, a platform development for detecting low abundant biomarker is required. Prostate cancer specific antigen (PSA) is investigated using immunoassay in microfluidic platform. The components of the immunoassay have been characterised.