| Microfluidic systems are increasingly becoming prevalent in both research and commercial applications. The concept of 'lab on a chip' (LOC) has sparked tremendous research and development into physically miniaturizing laboratory components into portable systems. Furthermore, it promises to reduce the quantity of reagents used for analysis. It is a promising field of research that, if successful, will allow for integration of engineering, biology, chemistry, and medicine (often understood and applied at the macroscale), to be effectively applied at the microscale. The microscale offers numerous advantages, including diffusion, surface tension, and laminar flow, all of which can be elegantly leveraged together to realize microfluidic systems for numerous applications, including but not limited to biological and/or chemical sensors, chemical synthesis, LOC diagnostic tools, drug delivery, cellomics, gene chips, and optics.; This research work has focused on the development of a variety of microfluidic components and systems: Programmable autonomous micromixers and micropumps are crucial components to handle and manipulate fluids at the microscale; on-chip adaptive microfluidic cooling devices can find applications in biological microfluidics which has necessitated on-chip temperature control; smart liquid microlenses have the potential to advance optical imaging, medical diagnostics, bio-optical microfluidic systems, and lab-on-a-chip technologies. These devices are realized by integrating metal and polymer microstructures using a merged fabrication platform based on integrated-circuit derived microelectromechanical systems and liquid-phase photopolymerization processing. An external rotating magnetic stirrer couples with an in situ fabricated nickel impeller in the micromixer, micropump, and cooling device. Previous researchers have developed a variety of similar microfluidic components and systems to handle and manipulate fluids; however, many of these existing systems require complex on-board electronics for control and/or are unable to realize individual control of a single component in a system array without complicated electronics. To simplify and overcome many of these limitations, stimuli-responsive hydrogels (i.e., sensitive to light, temperature, pH, electric fields, antigens), which exhibit volumetric expansion and contraction, are photopatterned at the axle of the impeller. The hydrogel's inherent transduction of chemical energy to mechanical energy is readily utilized to enable the microfluidic system to autonomously adapt to its local environmental parameter. |
