This thesis presents the design of a scratch drive actuator (SDA) for Micro Motor Application. In accordance with the force needed to drive the mechanism, the relationship among SDA output force, geometries, and applied voltage is first constructed by employing the principle of virtual work. Having selected the topology of the device, the equations governing the motions and the forces of the micro motor and the actuator can be derived. The SDA and the associated micro motor mechanism are designed by considering the characteristics of Multi-User MEMS Processes, or MUMPs fabrication process. There are several types of SDA used for step motor application being designed and fabricated as illustrative samples. The chip well defined in MUMPs is released by immersing the chip in a bath of HF. It is followed by cleaning in DI water and IPA on a hot plate at 150¢J to reduce stiction.¡@The samples are inspected by OM and SEM, respectively.¡@The experimental and analytical results indicate the practicability of the proposed design concept.

This work examined the design, fabrication, and testing of a bio-mimetic MEMS earthworm crawler with external actuators. The micro-earthworm consisted of a passive mobile shuttle with two flexible diamond shaped segments; each segment was independently squeezed by a pair of stationary chevron-shaped thermal actuators. By applying a specific sequence of squeezes to the earthworm segments, the shuttle could be driven backwards or forwards. Unlike existing inchworm drives, which use separate clamping and thrusting motors, the earthworm motor applies only clamping forces and lateral thrust is produced by the shuttle’s compliant geometry. A study of existing crawler work was performed; to the author’s knowledge, this was the first micro-crawler to achieve both clamping force and lateral motion using the same actuators. The earthworm assembly was fabricated using the POLYMUMPs process, with planar dimensions of 400 µm wide by 800 µm long. The stationary earthworm motors operated within the range of 4-9 V, and 0-10 kHz; these motors provided a maximum shuttle range of motion of 350 µm (~half the size of the device), a maximum shuttle speed of 17,000 µm /s at 10 kHz, and a maximum DC shuttle force of 80 µN. The shuttle speed was found to vary linearly with both input voltage and input frequency; the shuttle force was found to vary linearly with actuator voltage. The tested design had higher force, range, and speed (per device footprint) than most other existing designs. Future work recommendations included the implementation of multiple motors and a closed loop control system to allow an indefinite range of motion, as well as the investigation of a two degree of freedom crawler. / THE DESIGN AND TESTING OF A BIO-INSPIRED HIGH PRECISION, HIGH SPEED, LONG RANGE PERISTALTIC MICRO-MOTOR

This thesis conducts numerical and experimental studies of the nonlinear electrokinetic motion of heterogeneous particles in microfluidic systems and their corresponding applications in laboratory-on-a-chip (LOC) systems. Induced-charge electrokinetic (ICEK) phenomena flow is generated by applying an external electric field to a conducting particle immersed in an aqueous solution. As a result of this field, micro-vortices form around the conducting particle. Using this phenomenon, many shortcomings of classical electrokinetics (e.g. poor mixing, leakage, back flow problem) can be improved. This thesis proposes and investigates a complete 3-D numerical multi-physics method to calculate the induced zeta potential on the conducting surface of a heterogeneous object. To model the ICEK motion of a heterogeneous particle in a DC electric field, the moving grid technique is used to conduct the particle-fluid simulation. It was numerically shown that the vortices form near the conducting surface of a particle. Both transitional and rotational motions of heterogeneous particles are investigated. A set of novel experiments are designed and conducted to investigate several aspecs of ICEK. It is demonstrated for the first time that four vortices form around a conducting sphere in contact with an aqueous solution while the DC electric field is applied. The motions of heterogeneous particles are experimentally studied. The speed of a heterogeneous particle is compared with the same size non-conducting particle under the same experimental conditions and it is shown that the heterogeneous particle moves significantly faster than the non-conducting particle. It is also shown that the micro-vortices on the conducting section of the heterogeneous particle act like an engine and push the particle to move faster. These experiments verify the results of our simulation studies. We introduce three applications for induced-charge electrokinetic phenomena in ths thesis: ICEK micro-valve, ICEK micro-mixer, and ICEK micro-motor, which can be used in microfluidics and lab-on-a-chip devises. This ICEK micro-valve significantly improves many shortcomings of other micro-valves reported in the literature (such as leakage, considerable dead volume and complicated fabrication processes). Our ICEK micro-mixers take the advantages of induced micro-vortices and boost the mixing process in a micro-channel. As a result well mixed homogeneous (100%) mixture could be obtained at the downstream of the mixer. Our proposed no-contact ICEK micro-motor rotates as long as the DC electric field is being applied. This thesis develops a new understanding of several ICEK phenomena and applications related to heterogeneous particles. The 3D numerical model developed in this thesis along with the experimental studies are capable of describing the ICEK motion of a heterogeneous particle and is a considerable step to calculate the ICEK phenomena for real-world applications. This thesis, for the first time, experimentally visualized and verified the induced micro-vortices around conducting particles under applied DC electric field. The proposed ICEK micro-mixers, valve and motor can be used in various LOC devices and applications.

This thesis conducts numerical and experimental studies of the nonlinear electrokinetic motion of heterogeneous particles in microfluidic systems and their corresponding applications in laboratory-on-a-chip (LOC) systems. Induced-charge electrokinetic (ICEK) phenomena flow is generated by applying an external electric field to a conducting particle immersed in an aqueous solution. As a result of this field, micro-vortices form around the conducting particle. Using this phenomenon, many shortcomings of classical electrokinetics (e.g. poor mixing, leakage, back flow problem) can be improved. This thesis proposes and investigates a complete 3-D numerical multi-physics method to calculate the induced zeta potential on the conducting surface of a heterogeneous object. To model the ICEK motion of a heterogeneous particle in a DC electric field, the moving grid technique is used to conduct the particle-fluid simulation. It was numerically shown that the vortices form near the conducting surface of a particle. Both transitional and rotational motions of heterogeneous particles are investigated. A set of novel experiments are designed and conducted to investigate several aspecs of ICEK. It is demonstrated for the first time that four vortices form around a conducting sphere in contact with an aqueous solution while the DC electric field is applied. The motions of heterogeneous particles are experimentally studied. The speed of a heterogeneous particle is compared with the same size non-conducting particle under the same experimental conditions and it is shown that the heterogeneous particle moves significantly faster than the non-conducting particle. It is also shown that the micro-vortices on the conducting section of the heterogeneous particle act like an engine and push the particle to move faster. These experiments verify the results of our simulation studies. We introduce three applications for induced-charge electrokinetic phenomena in ths thesis: ICEK micro-valve, ICEK micro-mixer, and ICEK micro-motor, which can be used in microfluidics and lab-on-a-chip devises. This ICEK micro-valve significantly improves many shortcomings of other micro-valves reported in the literature (such as leakage, considerable dead volume and complicated fabrication processes). Our ICEK micro-mixers take the advantages of induced micro-vortices and boost the mixing process in a micro-channel. As a result well mixed homogeneous (100%) mixture could be obtained at the downstream of the mixer. Our proposed no-contact ICEK micro-motor rotates as long as the DC electric field is being applied. This thesis develops a new understanding of several ICEK phenomena and applications related to heterogeneous particles. The 3D numerical model developed in this thesis along with the experimental studies are capable of describing the ICEK motion of a heterogeneous particle and is a considerable step to calculate the ICEK phenomena for real-world applications. This thesis, for the first time, experimentally visualized and verified the induced micro-vortices around conducting particles under applied DC electric field. The proposed ICEK micro-mixers, valve and motor can be used in various LOC devices and applications.