This study aims to develop a new fabrication process to create high-precision patterned shape memory alloy (SMA) bimorph micro-actuators by the e-beam evaporation technique. To examine the effect of the annealing process on nitinol (NiTi) thin film characteristics, the as-deposited and annealed NiTi thin films are, respectively, investigated. X-ray diffraction (XRD) results demonstrate the crystallization of NiTi thin films after annealing at 600 °C. The transformation behaviors of NiTi thin films during heating and cooling are studied using the differential scanning calorimeter (DSC). Furthermore, scanning electron microscopy (SEM) images indicate that SMA bimorph micro-actuators with high-precision features can be fabricated by the lift-off process, without any wet or dry etching procedures, and their thermomechanical behaviors are experimentally verified by comparing them with that of finite element analysis simulation results.

This paper presents the development of a prototype exfoliation tool and process for the fabrication of thin-film, single crystal silicon, which is a key material for creating high-performance flexible electronics. The process described in this paper is compatible with traditional wafer-based, complementary metal–oxide–semiconductor (CMOS) fabrication techniques, which enables high-performance devices fabricated using CMOS processes to be easily integrated into flexible electronic products like wearable or internet of things devices. The exfoliation method presented in this paper uses an electroplated nickel tensile layer and tension-controlled handle layer to propagate a crack across a wafer while controlling film thickness and reducing the surface roughness of the exfoliated devices as compared with previously reported exfoliation methods. Using this exfoliation tool, thin-film silicon samples are produced with a typical average surface roughness of 75 nm and a thickness that can be set anywhere between 5 μ m and 35 μ m by changing the exfoliation parameters.

This paper presents graphene growth on Pt thin films deposited with four different adhesion layers: Ti, Cr, Ta, and Ni. During the graphene growth at 1000 °C using conventional chemical vapor deposition (CVD) method, these adhesion layers diffuse into and alloy with Pt layer resulting in graphene to grown on different alloys. This means that each different adhesion layers induce a different quality and number of layer(s) of graphene grown on the Pt thin film. This paper presents the feasibility of graphene growth on Pt thin films with various adhesion layers and the obstacles needed to overcome in order to enhance graphene transfer from Pt thin films. Therefore, this paper addresses one of the major difficulties of graphene growth and transfer to the implementation of graphene in nano/micro-electromechanical systems (NEMS/MEMS) devices.

Fresnel zone plates (FZPs) have been gaining a significant attention by industry due to their compact design and light weight. Different fabrication methods have been reported and used for their manufacture but they are relatively expensive. This research proposes a new low-cost one-step fabrication method that utilizes nanosecond laser selective oxidation of titanium coatings on glass substrates and thus to form titanium dioxide (TiO 2 ) nanoscale films with different thicknesses by controlling the laser fluence and the scanning speed. In this way, phase-shifting FZPs were manufactured, where the TiO 2 thin-films acted as a phase shifter for the reflected light, while the gain in phase depended on the film thickness. A model was created to analyze the performance of such FZPs based on the scalar theory. Finally, phase-shifting FZPs were fabricated for different operating wavelengths by varying the film thickness and a measurement setup was built to compare experimental and theoretical results. A good agreement between these results was achieved, and an FZP efficiency of 5.5% to 20.9% was obtained when varying the wavelength and the oxide thicknesses of the zones.

A computational model to investigate the flushing of electric discharge machining (EDM) debris from the interelectrode gap during the spray-EDM process is developed. Spray-EDM differs from conventional EDM in that an atomized dielectric spray is used to generate a thin film that penetrates the interelectrode gap. The debris flushing in spray-EDM is investigated by developing models for three processes, viz., dielectric spray formation, film formation, and debris flushing. The range of spray system parameters including gas pressure and impingement angle that ensure formation of dielectric film on the surface is identified followed by the determination of dielectric film thickness and velocity. The debris flushing in conventional EDM with stationary dielectric and spray-EDM processes is then compared. It is observed that the dielectric film thickness and velocity play a significant role in removing the debris particles from the machining region. The model is used to determine the spray conditions that result in enhanced debris flushing with spray-EDM.

A novel method of using atomized dielectric spray in micro-electric discharge machining (EDM) (spray-EDM) to reduce the consumption of dielectric is developed in this study. The atomized dielectric droplets form a moving dielectric film up on impinging the work surface that penetrates the interelectrode gap and acts as a single phase dielectric medium between the electrodes and also effectively removes the debris particles from the discharge zone. Single-discharge micro-EDM experiments are performed using three different dielectric supply methods, viz., conventional wet-EDM (electrodes submerged in dielectric medium), dry-EDM, and spray-EDM in order to compare the processes based on material removal, tool electrode wear, and flushing of debris from the interelectrode gap across a range of discharge energies. It is observed that spray-EDM produces higher material removal compared to the other two methods for all combinations of discharge parameters used in the study. The tool electrode wear using atomized dielectric is significantly better than dry-EDM and comparable to that observed in wet-EDM. The percentage of debris particles deposited within a distance of 100 μ m from the center of EDM crater is also significantly reduced using the spray-EDM technique.

Wrinkling of thin films is a strain-driven process that enables scalable and low-cost fabrication of periodic micro- and nano-scale patterns. In the past, single-period sinusoidal wrinkles have been applied for thin-film metrology and microfluidics applications. However, real-world adoption of this process beyond these specific applications is limited by the inability to predictively fabricate a variety of complex functional patterns. This is primarily due to the inability of current tools and techniques to provide the means for applying large, accurate, and nonequal biaxial strains. For example, the existing biaxial tensile stages are inappropriate because they are too large to fit within the vacuum chambers that are required for thin-film deposition/growth during wrinkling. Herein, we have designed a compact biaxial tensile stage that enables (i) applying large and accurate strains to elastomeric films and (ii) in situ visualization of wrinkle formation. This stage enables one to stretch a 37.5 mm long film by 33.5% with a strain resolution of 0.027% and maintains a registration accuracy of 7 μ m over repeated registrations of the stage to a custom-assembled vision system. Herein, we also demonstrate the utility of the stage in (i) studying the wrinkling process and (ii) fabricating complex wrinkled patterns that are inaccessible via other techniques. Specifically, we demonstrate that (i) spatial nonuniformity in the patterns is limited to 6.5%, (ii) one-dimensional (1D) single-period wrinkles of nominal period 2.3 μ m transition into the period-doubled mode when the compressive strain due to prestretch release of plasma-oxidized polydimethylsiloxane (PDMS) film exceeds ∼18%, and (iii) asymmetric two-dimensional (2D) wrinkles can be fabricated by tuning the strain state and/or the actuation path, i.e., the strain history. Thus, this tensile stage opens up the design space for fabricating and tuning complex wrinkled patterns and enables extracting empirical process knowledge via in situ visualization of wrinkle formation.

In this paper, precise P3 scribing of thin-film solar cells (AZO/CIGS/Mo/Glass) via a picosecond laser is investigated. A parametric study is carried out for P3 scribing to study the effects of laser fluence and overlap ratio on ablation depth and slot quality, supported by the numerical prediction using a two-temperature model. The optimum scribing conditions are determined, and the potential processing speed is increased. Laser induced periodic surface structures are also presented after the scribing process, which can potentially enhance the absorption of the cell surface and consequently increase the cell efficiency.