Polydimethylsiloxane(PDMS) thin films have the advantages of flexible , good chemicophysical properties , low energetic surface that supports the vertical anchoring of liquid crystal molecules , could be fabricated easily by Replica Molding Method , low cost and good optically transparent. We study of the use of PDMS in flexible liquid crystal displays and the Electro-Optical properties of LC flexible cell. In experiment we use PDMS to fabricate vertical alignment layer , elastomer substrate and spacer to maintain the Electro-Optical properties in flexible displays.

Mechanical rubbing alignment is the most common used method in the liquid crystal display manufacturing process. However, it may cause dust and electrostatic problem. In this study, we investigate effects of low surface free energy Polydimethylsiloxane (PDMS) on orientation of liquid crystal molecules in a confined structure and fabricate alignment layer using PDMS. In the present study, we show that liquid crystal molecules are arranged in consistency without rubbing process and it may be a new homogeneously aligned mode in liquid crystal display. In this thesis, liquid crystal textures were observed using polarizing optical microscopy (POM). It was found that liquid crystal molecules were homogeneously aligned in PDMS holes. In addition, this thesis indicated that how liquid crystal alignment affected by PDMS layer thickness and surface treatment. We learned that using treatment of JALS-9800 film on the bottom substrate from liquid crystal texture can obtain the arrangement of expected liquid crystal molecules. The liquid crystal device can be produced using PDMS structure. The measurement of electro-optic characteristics showed that the circular shape in the confined structure had better transmittance and contrast ratio.

In this study, the PDMS with microgroove structure was used controlling pretilt anlge of liquid crystal. Polydimethylsiloxane, also called PDMS, is one transparent, flexible, and stable material. It was usually fabricated the flexible display and so on. Based on Groove Theory, we can create the microgroove structure with the different groove depths and the width of the lines on PDMS by Replica Molding Method, in order to controlling the pretilt anlge of liquid crystal. We used the photoresist with different thickness to developing, and then the groove will get with different depth of groove. The PDMS was injected to the surface of groove with slow motion. When the liquid-like PDMS was curing, the PDMS can readily convert into solid elastomers by cross-linking. Finally, The microgrooved PDMS structure will obtain.

Multi-domain Vertical Alignment Flexible Liquid Crystal Display based on photolithography and replica-Molding method has been demonstrated. In order to maintain a uniform cell gap between flexible substrate,the microstructures were fabricated with polydimethylsiloxane (PDMS) material by replica-molding method. The microstructures master were designed and fabricated using a photosensitive resin (SU-8) by photolithography. The microstructures of pixel-encapsulated walls enhance the mechanical strength to prevent the liquid crystal molecules flow in the bend state deformations. Besides, the elastomeric material, PDMS, provide weak surface energy and induce vertical alignment for liquid crystal spontanelusly without any surface treatment. The microstructure protrusions made by PDMS can provide multi-domain vertical alignment (MVA) effect with wide viewing angle and high contrast ratio. Therefore, this method could be implemented for achieving multi-domain vertical alignment on a flexible LCD applications. The flexible LCD have great stability reproducibility, durability and good electro-optical performances.

The InsulPatch is a novel integrated patch-pump device used to deliver drugs, especially macromolecular drugs that are difficult to deliver through an oral pathway and that require transdermal delivery. The patch-pump is a promising replacement for conventional syringes and battery-powered pumps because it is slim, powerless, painless, and relatively inexpensive. The majority of this thesis focuses on the fabrication and testing of microfluidic devices for the delivery of insulin, which is a model drug that is widely used and needs to be delivered transdermally. In this thesis, we demonstrate the fabrication of the patch-pump, which includes an insect-mimetic microfluidic pump fabricated using photolithography and replica molding, and a microneedle array fabricated using 3D printing. The microfluidic pump is used to drive the fluid flow powered by pressurized air or the user’s pulse, and the microneedle array is used to inject the fluid through the skin painlessly. Using pressurized air-driven flow testing, we have tested the flow rate across microfluidic pumps of various flow channel widths over a range of physiologically relevant actuation frequencies and pressures. We have found that for the specific channel design we have been using, the flow rate generally positively correlates with the actuation pressure. For devices with wider flow channels, the flow rate generally negatively correlates with the actuation frequency, whereas the flow rate increases and then decreases with increasing actuation frequency for devices with narrower flow channels. This property of these devices is beneficial in insulin delivery because the demand for insulin is generally reduced in vigorous exercise (with elevated heart rate/actuation frequency) and increased in hypertension patients (with elevated blood/actuation pressure). A major future direction of the study is to test a wide range of device designs in a sample of human subjects by attaching the device onto the wrist and measuring the pulse-driven flow across the device. We can further change the channel design parameters of the device so that it will be ideal for insulin delivery. Using the ex vivo flow testing and human subject data, we can further tailor the device design to specific patients using a genetic algorithm-guided optimization based on the heart rate and blood pressure of the patient and the desired flow rate. We will also perform computational modeling using COMSOL Multiphysics to predict the flow across devices of different designs as well as to understand the physics behind the pulse-driven flow. Finally, a 3D-printed insulin reservoir will be incorporated into our patch-pump system for the storage of U-500 insulin. / M.S. / The InsulPatch is a slim, powerless device (“patch-pump”) that can be used to deliver drugs through the skin, especially designed for drugs that are difficult to deliver orally. The patch technology is a promising replacement for conventional injection using syringes and bulky battery-powered pumps. At this stage, the primary drug that our device aims to deliver is insulin, which generally needs to be delivered through the skin. In this thesis, we demonstrate how our patch-pump is made and how its performance is tested. The patch-pump has two parts: the microfluidic pump and the microneedle array. The microfluidic pump is fabricated using a technique called photolithography, in which a photosensitive polymer is selectively cured by UV light, and replica molding, in which the precursor of another polymer is poured on a mold and cured. The microneedle array is made using 3D printing and designed in such a way so that it can be readily connected to the microfluidic pump. The microfluidic pump is used to drive the fluid flow powered by the user’s pulse, and the microneedle array is used to inject the fluid through the skin painlessly. Through testing the flow across the microfluidic pump prototypes using pressurized air, we characterized the correlation between the flow rate of fluid across the device and parameters including the actuation pressure and frequency of the pressurized air as well as the width of the flow channel. Future directions of the study include testing the devices in human subjects to characterize pulse-driven flow across the devices, computational modeling of the devices, and further changes of the device design to optimize the performance of the device. We will also optimize the device design computationally to tailor the device design to specific diabetic patients. Finally, we will incorporate a 3D-printed insulin reservoir into our system for the storage of insulin solution. / Withhold all access to the ETD for 1 year / patent / I hereby certify that, if appropriate, I have obtained and submitted with my ETD a written permission statement from the ower(s) of each third part copyrighted matter to be included in my thesis or dissertation, allowing distribution as specified above. I certify that the version I submitted is the same as that approved by my advisory committee.