Enikov, E. T., & Lazarov, K. V. (2003). Metallic microactuators based on sacrificial layer SU8 release. American Society of Mechanical Engineers, Micro-Electromechanical Systems Division Publication (MEMS), 5, 133-139.
Abstract:
Thermal micro-actuators are a promising solution to the need for large-displacement, low-power MEMS actuators. Potential applications of these devices are micro-relays, tunable impedance RF networks, and miniature medical instrumentation. In this paper the development of thermal microactuators based on SU8 is described. A polymeric sacrificial layer allows the removal of the SU8 mold to occur without the use of harsh etching conditions. In addition to silicon non-traditional for MEMS substrates such as RF-printed circuit boards have also been successfully utilized to fabricate the devices. The PCB-based devices exhibited similar characteristics, thus opening the possibility of integrating RF MEMS directly on PCBs. The actuators were benchmarked with respect to power consumption, stroke, and response time. The fabricated nickel actuators are shown to be robust with displacements in the range of 76 micrometers using 80 mW of power. Actual cooling transients were captured using a two-step constant-current excitation method. It is further demonstrated through analytical models that the thermal cooling times limit the bandwidth of these devices below 1KHz. Several commercially relevant applications of the developed actuators are also discussed. One such application is a vibro-tactile display for disabled individuals.
McCafferty, S., Levine, J., Schwiegerling, J., & Enikov, E. T. (2017). Goldmann applanation tonometry error relative to true intracameral intraocular pressure in vitro and in vivo. BMC OPHTHALMOLOGY, 17.
Szabo, Z., Enikov, E. T., & Kyselica, R. (2017). NANOFACTURE: SENIOR DESIGN EXPERIENCE IN NANOTECHNOLOGY. PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2016, VOL. 5.
McCafferty, S. J., Schwiegerling, J. T., & Enikov, E. T. (2012). Corneal surface asphericity, roughness, and transverse contraction after uniform scanning excimer laser ablation. Investigative Ophthalmology and Visual Science, 53(3), 1296-1305.
PMID: 22297493;Abstract:
Purpose. To examine the interaction between the excimer laser and residual tissue. Methods. Ten cadaveric porcine eyes with exposed corneal stroma and plastic test spheres underwent uniform 6-mm ablation with a scanning excimer laser. Corneal profilometry of the central 3 mm was measured with submicrometer resolution optical interferometry, before and after uniform excimer ablation. Eleven surface-marked eyes were photomicrographed before and after excimer ablation. Images were superimposed, and mark positional changes were measured. Results. Uniform scanning excimer laser ablation of the corneal stroma produces a significant central steepening and peripheral flattening in the central 3-mm of the diameter. The central 1-mm corneal curvature radius (r) decreased from r = 10.07 ± 0.44 (95% CI) to 7.22 ± 0.30 mm, and the central 2-mm radius decreased from r = 10.16 ± 0.44 to 8.10 ± 0.43 mm. Q values, measuring asphericity in the 2-mm radius of the central cornea, were significantly lower before than after ablation (-5.03 ± 4.01 vs. -52.4 ± 18.7). Surface roughness increased significantly from 0.65 ± 0.06 to 1.75 ± 0.32 μm after ablation. The central 2 mm of the stromal surface contracted by 2.21% ± 0.80% at a sustained temperature of 5°C. Ablation of plastic spheres produced no significant change. Conclusions. The excimer laser interacts with the nonablated residual stromal surface in a characteristic fashion not seen with isotropic, inorganic material. Increases in asphericity, surface roughness, surface contraction, and stromal morphologic changes are supportive of this interaction. The surface changes demonstrated may be indicative of temperature-induced transverse collagen fibril contraction and stress redistribution, or the ablation threshold of the stromal surface may be altered. This phenomenon may be of increased importance using lasers with increased thermal load. © 2012 The Association for Research in Vision and Ophthalmology, Inc.
Enikov, E. T., & Lazarov, K. V. (2003). Composite Thermal Micro-Actuator Array for Tactile Displays. Proceedings of SPIE - The International Society for Optical Engineering, 5055, 258-267.
Abstract:
Tactile perception of complex symbols through tactile stimulation is an exciting application of a phenomenon known as tactile illusion (TI). Sensation of motion on the skin can be produced by a limited number of discrete mechanical actuators applying light pressure over the skin. This phenomenon can thus be used as a neurophysiological testing tool to determine central and peripheral nervous system injury as well as providing an additional human-machine communication channel. This paper describes the development of a 4 × 5 actuator array of individual vibrating pixels for fingertip tactile communication. The array is approximately one square centimeter and utilizes novel micro-clutch MEMS technology. The individual pixels are turned ON and OFF by pairs of microscopic composite thermal actuators, while the main vibration is generated by a vibrating piezo-electric plate. The physiological parameters required for inducing tactile illusion are described. The fabrication sequence for the thermal micro-actuators along with actuation results are also presented.
