Development of microcantilever biosensing platforms
MetadataShow full item record
Microcantilever sensor system as a promising field attracted much attention recently. This system has the potential to be applied for a biosensing technology which is parallel reference, label free, sensitive and real time. In this thesis, polyimide has been selected as a material to fabricate cantilever due to its excellent physical, electrical and mechanical properties, on top of its cost advantage. Importantly, we showed it is feasible to microfabricate large array of microcantilever sensors with high-power UV laser directly. It is low cost and rapid, the parameters for laser direct writing fabrication has been studied. The thesis also shows that it is possible to functionalise the polyimide film first and subsequently cut it to functionalised cantilever sensor array. The unique fabrication and functionalisation process can solve the problem of high-cost microfabrication using silicon and low-efficient functionalisation using capillary tubing all together. In addition, the fabrication process has been further developed to avoid the problem of the cross contamination from receptors on both sides. With this improvement, we developed an internally referenced microcantilever biosensors system for DNA hybridization detection. Different receptors can be coated on each side of the polymer film before fabricating to cantilever biosensors This newly developed capability enables us to coat receptors with similar but slightly different biological properties on each side of the cantilever sensor, a process which is extremely difficult by using conventional capillary tubing methods due to the possibility of thiol exchange on surfaces and hence cross-contamination. A polyimide microcantilever sensor with embedded microfluidic channel has been developed in this thesis. Photoresist material is used to form the precise microfluidic channel within the microcantilever device. The multilayer polymer film device is still soft enough to operate in static mode. The main advantage of the system presented here is that since the device is made entirely of polymer materials, the fabrication process is simple and low-cost. The magnetic beads have been used to amplify the signal of the biosensing processing; the application of polyimide microfluidic microcantilevers to the detection of Cryptosporidium and thrombin is reported in this thesis. Paper based autonomous micocantilever system has also been investigated in this thesis. We build a cantilever system without external pump or force with paper and magnetic field. The limitation of the system is that it takes too much time to pump magnetic beads through the cantilever with capillary. However, we found that it has the potential to develop a long time range timer based on the slowest property. Different methods have been investigated to slow down the speed, when liquid pass through the paper microfluidic. Finally, we demonstrate some timer devices whose ranges are from minutes to month. The devices have the potential to be used as time-based diagnostic assays, food label, etc.