Micromixer is one of the most significant components of microfluidic systems, which manifest essential applications in the field of chemistry and biochemistry. Achieving complete mixing performance at the shortest micro channel length is essential for a successful micromixer design. We have developed five novel micromixers which have advantages of high efficiency, simple fabrication, easy integration and ease for mass production. The design principle is based on the concept of splitting-recombination and chaotic advection. Numerical models of these micromixers are developed to characterize the mixing performance. Experiments are also carried out to fabricate the micromixers and evaluate the mixing performance. Numerical simulation for different parameters such as fluids properties, inlet velocities and microchannel cross sectional sizes are also conducted to investigate their effects on the mixing performance. The results show that critical inlet velocities can be predicted for normal fluid flow in the micromixers. When the inlet velocity is smaller than the critical value, the fluids mixing is dominated by mechanism of splitting-recombination, otherwise, it is dominated by chaotic advection. If the micromixer can tolerate higher inlet velocity, the complete mixing length can be further reduced. Our simulation results will provide valuable information for engineers to design a micromixer by choosing appropriate geometry to boost mixing performance and broaden implicational range to fit their specific needs. Accurate and complicated fluidic control, such as flow mixing or reaction, solution preparation, large scale combination of different reagents is also important for bio-application of microfluidics. A proposal microfluidic system is capable of creating 1024 kinds of combination mixtures. The system is composed of a high density integrated microfluidic chip and control system. The high density microfluidic chip, which is simply fabricated through soft lithography technique, contains a pair of 32 flow channels that can be specifically addressed by each 10 actuation channels based on principle of multiplexor in electronic circuits. The corresponding hardware and software compose the control system, which can be easy fabricated and modified, especially for prototype machine developing. Moreover, the control system has general application. Experiments are conducted to verify the feasibility of this microfluidic system for multi-optional solution combination. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2013.

In order for microfluidics devices to be marketable, they must be inexpensive and easy to use. Two projects were pursued in this study for this purpose. The first was the design of a chip alignment system for visual feedback, in which a two-layer microfluidic chip was placed under a camera and an image processing and linear algebra program aligned a computer model to it. The system then translated the new locations of air valves and could detect valve activation in a chip filled with food coloring. The second was the design of a cheap, portable system to detect phosphorus in water. This system could not be completed due to time constraints, but the methods were detailed, and design ideas were laid out for future work. / by Ian Gerstel. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

This thesis presents the method of state diagram synthesis and the development of a computer program for designing fluidic sequential feedback • control circuits of the fundamental mode. A paper on state diagram synthesis was authored by Chen and Lee, presented in Detroit and published as ASME paper 73-WA/Flcs-2 in 1973. Hypothetical systems are illustrated by using series of events characterized by the piston positions of some double-acting pneumatic cylinders. In these systems , an action can only begin when the previous action has been completed. Every extension or retraction of a piston is memorized and manifested by a flip-flop element in the feedback circuit. If different combina- tions of control signals result from different combinations of feedback signals, the logic design is straightforward. Otherwise secondary variables are needed to differentiate between repeated appearances of some ambiguous input combinations. A secondary variable is obtained as the output of a fluidic flip-flop with set and reset inputs. When a sufficient number of secondary variables are obtained, they are combined with the feedback signals. Considerations of these variables and their associated logic complementary "don't-care" conditions leads to a set of simplified control equations. The complete process of the circuit design, using state diagram synthesis, has been programmed for a digital computer. After the control equations are obtained , one can take the signal transmission characteristics into account in order to build a hazard-free circuit.

Microvalves are essential components of the miniaturization of the fluidic systems to control of fluid flow in a variety of applications as diverse as chemical analysis systems, micro-fuel cells, and integrated fluidic channel arrangements for electronic cooling. Using microvalves, these systems offer important advantages: they can operate using small sample volumes and provide rapid response time. This PhD dissertation presents the world first electromagnetically actuated microvalve fabricated on a single wafer with CMOS compatibility. In this dissertation, the design, fabrication, and testing results of two different types of electromagnetic microvalves are presented: the on/off microvalve and the bistable microvalve with latching mechanism. The microvalves operate with power consumption of less than 1.5 W and can control the volume flow rate of DI water, or a 50% diluted methanol solution in the range 1 - 50 µL in. The leaking rate of the on/off microvalve is the order of 30 nL/min. The microvalve demonstrated a response time for latching of 10 ms in water and 0.2 ms in air. This work has resulted in a US patent, application no. 10/699,210.Other inventions that have been developed as a result of this research are bidirectional, and bistable-bidirectional microactuators with latching mechanism, that can be utilized for optical switch, RF relay, micro mirror, nano indenter, or nano printings.