Eniko T Enikov
Associate Professor, BIO5 Institute
Professor, Aerospace-Mechanical Engineering
Department Affiliations
(520) 621-4506
Work Summary
Dr. Enikov's area of expertise is the design of micro-actuators, MEMS devices, and sensors. Ongoing projects include the production of Inflatable Drug-Delivery Stents through the process of Dynamic Stabilization of Electro-Spinning. The research will examine theoretically the feasibility of trapping charged fibers and will establish the required trapping parameters.
Research Interest
Dr. Enikov's area of expertise is the design of micro-actuators, MEMS devices, and sensors. After completion of his training, he established the Advanced Micro- and Nanosystems Laboratory at the University of Arizona, where they have carried out numerous research projects involving precision assembly of micro-systems under optical feedback, development of wet actuators using ion-exchange polymers, pressure sensors, and accelerometers. In the last 8-years, his research has applied micro-technology to the development of medical devices. More specifically, they have developed a through-the-eye lid tactile tonometer capable of estimating intraocular pressure using an array of MEMS sensors. A second invention pertains to the development of an implantable ventricular peritoneal shunt with flow sensing capabilities. The present project represents a major focus of his laboratory. They have completed several early-stage studies on tactile tonometery supporting the present application. Given Dr. Enikov's technical background and prior effort in the area of tactile tonometery, he believes he is uniquely qualified to lead the proposed effort.

Publications

Enikov, E. T., & Palaria, A. (2004). Charge writing in silicon-silicon dioxide for nano-assembly. Nanotechnology, 15(9), 1211-1216.

Abstract:

Interest in using electrostatics for active nano-assembly has grown significantly over the last five years. One common electret structure for such electrostatic constructs is the silicon-silicon dioxide interface. In this paper, an experimental and mathematical analysis of the process of writing negative charge spots in Si-SiO2 is presented. It is demonstrated that controlling the spread of the charge can reduce the spot size and the drop in written potential. Simulation results of a one-dimensional charging model that assumes tunnelling of electrons through the oxide and trapping within SiO2 are presented and compared with the experimental data. The model assumes charge trapping at the Si-SiO2 interface and none at the oxide-air interface or within the oxide bulk. Conducted experiments also show that although the lateral spread of charge places a lower limit on the minimum spot size in silicon-silicon dioxide structures, the use of a hydrophobic hexamethyldisilazane layer can be effective in improving the size stability of the written electrical spots.

White, E. L., & Enikov, E. T. (2007). Self-aligning electrostatic gripper for assembly of millimeter-sized parts. IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM.

Abstract:

In this study, the performance of several electrostatic grippers is evaluated. These grippers are designed to align millimeter scale parts to matching electrode geometry on the gripper surface. Friction between the gripper and part is overcome through ultrasonic excitation of the gripper by a piezoceramic element. The effect of different frequencies and amplitudes of excitation on alignment were observed. Additionally, the use of ultrasonic excitation to aid in part release after clamping was investigated. Under ideal conditions, part motion was most frequently observed in certain excitation frequency windows, which correspond to resonant modes of the part-gripper system. ©2007 IEEE.

Enikov, E. T., Gamez, C., Kanjiyani, S., Ganji, M., & Gill, J. (2011). Flexible electrode structures for thermo-tunneling applications. ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 4(PARTS A AND B), 1657-1663.

Abstract:

Combined thermionic emission and tunneling of hot electrons (thermo-tunneling) has emerged as a potential new solid-state cooling technology. Practical implementation of thermo-tunneling, however, requires the formation of a nanometer-sized gap spanning macroscopically significant surfaces. Thermo-tunneling of hot electrons across a few-nanometer gap has application to vacuum electronics, flat panel displays, and holds great potential in thermo-electric cooling and energy generation. Development of new thermo-tunneling applications requires creation of a stable nanometer gap between two surfaces. This presentation is focused on our effort to investigate the feasibility of creating such gaps using distributed electro-magnetic forces arising in thin-film flexible structures. Early efforts based on rigid electrodes showed that the effective tunneling approaches 400 square-micrometers, which albeit small, could lead to useful practical systems. In this presentation, we report a theoretical and experimental investigation of a thin-electrode system which could lead to further increase on the effective tunneling area. The device under study consists of a thin membrane collector electrode (anode) suspended over the emitting electrode (cathode). The structure is placed in a vacuum enclosure with an externally generated magnetic field perpendicular to the current flow in the membrane. The resulting Lorentz force is then directed upwards, separating the two surfaces. A mathematical model of the steady-state operation of the device is presented along with predictions of the contact area and tunneling current. Essential output parameters of the model include a central contact area measured by its length (delta) and the thermo-tunneling current. Both parameters are determined as a function of the externally applied external potential and magnetic field. Numerical solutions of the model show two possible operating modes: (1) symmetric deformation with negligibly small current; and (2) asymmetric mode where the B-field controls the current and contact area. Copyright © 2011 by ASME.

Enikov, E. T., & Boyd, J. G. (1999). A thermodynamic field theory for anodic bonding of micro electro-mechanical systems (MEMS). International Journal of Engineering Science, 38(2), 135-158.

Abstract:

An anodic bond is modeled as a moving nonmaterial line forming the intersection of three material surfaces representing the unbonded conductor, the unbonded insulator, and the bonded interface. Global integral equations are written for the conservation of mass, momentum, and energy, Maxwell's equations, and the second law of thermodynamics. The global equations are then localized in the volume, the material surfaces, and the nonmaterial bond line. The second law is used to determine the thermodynamic conjugates in the thermodynamic potential and the dissipation inequality. It is demonstrated that the jump in the Poynting vector across a surface is equal to the surface Joule heating due to surface electric conduction currents. © 1999 Elsevier Science Ltd. All rights reserved.

Luce, A. V., Enikov, E. T., & Nelson, B. J. (2009). Design of automated digital eye palpation exam for intraocular pressure measurement. 2009 ICME International Conference on Complex Medical Engineering, CME 2009.

Abstract:

Elevated intraocular pressure (IOP) is a major risk factor for the degenerative eye disease glaucoma. Accurate indirect measurements of IOP are essential for glaucoma diagnosis and screening. This work presents an experiment developed to measure IOP in-vitro by simulating the technique of digital palpitation tonometry, a technique in which a trained examiner palpates the eyeball using the fingertips of both index fingers to "feel" the stiffness of the eye. The qualitative nature of this method and errors introduced by the subjectivity of the examiner mean that it is rarely used in comparison with other modern-day tonometry methods. However, this technique offers several potential advantages in that it can be performed outside of a clinical setting without the need for instrument sterilization or local anesthesia and may be less subject to measurement errors occurring in patients who have undergone refractive laser eye surgery. In order to quantify the mechanics of digital palpation tonometry, an automated experiment to measure the intraocular pressure of enucleated porcine eyeballs using mechanized digital palpation was designed and tested. This experiment has direct applications towards the development of a next-generation tonometer for glaucoma treatment. ©2009 IEEE.