Studies on droplet-microcantilever platform under fluid flow in mini wind tunnel

Fluid interaction of micro structures find numerous applications in bio medical field. This thesis consists of experimental studies on fluid interaction of micro structures under laminar flow using a mini wind tunnel. The interaction of microstructures such as micro cantilever and oil coated water droplet with fluid flow were tested and the experimental results are reported. A mini wind tunnel to test microstructures is designed and built. Design of the mini wind tunnel is validated by performing tip deflection studies of micro cantilever beams of different sizes in millimeter range. The interaction of micro cantilever beam with fluid flow is recorded using a recording camera. An image processing method is developed to extract results from recordings. Results from micro cantilever experiments suggest that tip deflection is highly influenced by beam length and beam thickness. Deformation of oil coated water droplets are tested under fluid flow. The micro structure is placed over a partially wetting surface and the deformation of the oil-droplet samples are tested using the mini wind tunnel. Effects of fluid velocity, droplet volume and oil concentration over droplet deformation are studied. Larger droplets deform more as compared to their smaller counterparts. Oil layer covers the water droplet entirely and reduces the influence of fluid force. Higher oil coating induces lesser deformation in droplets Oil coated droplets are subjected to fluid velocities greater than critical air velocity of the droplets to study the droplet shedding phenomena. Oil coated droplet slip easily as compared to the droplet with no oil coatings for a given fluid velocity. Also, oil coating improve the droplet shedding phenomena. However much higher oil coating slows down droplet shedding and the water droplet floats over pool of oil. Tip deflection of a microcantilever beam with a point load near the free end under the fluid flow is studied to develop fluid load augmented micro balance. Water droplets of various sizes are used to provide point load. The water droplet is placed over micro cantilever beam at dimensionless length ξ =0.8. An additional fluid load is provided using a mini wind tunnel. Tip deflection of the beam is tested for different fluid velocities. Results suggest that fluid load augments the tip deflection of micro cantilever beam. This thesis also develops fluid load augmented micro balance

Studies on droplet-microcantilever platform under fluid flow in mini wind tunnel

Fluid interaction of micro structures find numerous applications in bio medical field. This thesis consists of experimental studies on fluid interaction of micro structures under laminar flow using a mini wind tunnel. The interaction of microstructures such as micro cantilever and oil coated water droplet with fluid flow were tested and the experimental results are reported. A mini wind tunnel to test microstructures is designed and built. Design of the mini wind tunnel is validated by performing tip deflection studies of micro cantilever beams of different sizes in millimeter range. The interaction of micro cantilever beam with fluid flow is recorded using a recording camera. An image processing method is developed to extract results from recordings. Results from micro cantilever experiments suggest that tip deflection is highly influenced by beam length and beam thickness. Deformation of oil coated water droplets are tested under fluid flow. The micro structure is placed over a partially wetting surface and the deformation of the oil-droplet samples are tested using the mini wind tunnel. Effects of fluid velocity, droplet volume and oil concentration over droplet deformation are studied. Larger droplets deform more as compared to their smaller counterparts. Oil layer covers the water droplet entirely and reduces the influence of fluid force. Higher oil coating induces lesser deformation in droplets Oil coated droplets are subjected to fluid velocities greater than critical air velocity of the droplets to study the droplet shedding phenomena. Oil coated droplet slip easily as compared to the droplet with no oil coatings for a given fluid velocity. Also, oil coating improve the droplet shedding phenomena. However much higher oil coating slows down droplet shedding and the water droplet floats over pool of oil. Tip deflection of a microcantilever beam with a point load near the free end under the fluid flow is studied to develop fluid load augmented micro balance. Water droplets of various sizes are used to provide point load. The water droplet is placed over micro cantilever beam at dimensionless length ξ =0.8. An additional fluid load is provided using a mini wind tunnel. Tip deflection of the beam is tested for different fluid velocities. Results suggest that fluid load augments the tip deflection of micro cantilever beam. This thesis also develops fluid load augmented micro balance

Analysis of Detection Enhancement Using Microcantilevers with Long-Slit-Based Sensors

The present work analyzes theoretically and verifies the advantage of utilizing rectangular microcantilevers with long-slits in microsensing applications. The deflection profile of these microcantilevers is compared with that of typical rectangular microcantilevers under the action of dynamic disturbances. Various force-loading conditions are considered. The theory of linear elasticity for thin beams is used to obtain the deflection-related quantities. The disturbance in these quantities is obtained based on wave propagation and beam vibration theories. It is found that detections of rectangular microcantilevers with long-slits based on maximum slit opening length can be more than 100 times the deflections of typical rectangular microcantilevers. Moreover, the disturbance (noise effect) in the detection quantities of the microcantilever with long-slits is found to be always smaller than that of typical microcantilevers, regardless of the wavelength, force amplitude, and the frequency of the dynamic disturbance. Eventually, the detection quantities of the microcantilever with long-slits are found to be almost unaffected by dynamic disturbances, as long as the wavelengths of these disturbances are larger than 3.5 times the microcantilever width. Finally, the present work recommends implementation of microcantilevers with long-slits as microsensors in robust applications, including real analyte environments and out of laboratory testing