Eniko T Enikov

Eniko T Enikov

Professor, Aerospace-Mechanical Engineering
Associate Professor, BIO5 Institute
Department Affiliations
Contact
(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., Edes, G., Skoch, J., & Anton, R. (2014). Application of GMR Sensors to Liquid Flow Sensing. Journal of Microelectromechanical Systems, online.
Polyvás, P., Madarász, M., & Enikov, E. T. (2013). Development of Tactile Eye Stiffness Sensor. Experimental Mechanics, 53(5), 819-828.

Abstract:

This article describes the design of a novel trans-scleral tonometer based on the use of multiple force sensors forming a mechanical stiffness sensor. The approach is akin to an instrumented form of digital palpation tonometry in which manual paplation is used to infer the stiffness, and hence, the intraocular pressure of the eye. Force indentation data from multiple probes has been shown to correlate with the intraocular pressure (IOP) using encucleated porcine eyes. A noticeable amount of hysteresis has been observed during indentations at higher rate. Analysis of the experimental data indicates that stress relaxation (accommodation) in the visco-elastic corneo-scleral shell is the primary factor of the observed hysteresis. Further tests under different indentation rates show that the novel tonometer is expected to have an accuracy of ±1 mmHg when the indentation rate is kept below 0.5 mm/sec for pressure range of 10-35 mmHg. Using a calibrated finite element model of the measurement, the effect of lateral and angular misalignment is also examined. The results show that the position and orientation of the tactile sensor has to be controlled to within ±1 mm and ±3° in order to achieve a target accuracy of ±1 mmHg. © 2012 Society for Experimental Mechanics.

Scott, J., & Enikov, E. T. (2011). Novel temperature compensation technique for force-sensing piezoresistive devices. Journal of Micromechanics and Microengineering, 21(11).

Abstract:

A novel stress-insensitive piezoresistor in the shape of an annulus has been developed to be used in conjunction with a piezoresistive bridge for temperature-compensated force measurements. Under uniform stress conditions, the annular resistor shows near-zero stress sensitivity and a linear response to temperature excitation within test conditions of 24-34 °C. Annular resistors were placed in close proximity to stress-sensitive elements in order to detect local temperature fluctuations. Experiments evaluating the performance of the temperature compensator while testing force sensitivity showed a thermal rejection ratio of 37.2 dB and near elimination of low-frequency noise (drift) below 0.07 Hz. Potential applications of this annular resistor include use in multi-axis force sensors for force feedback microassembly, improvements in the simplicity and robustness of high precision microgram sensitive balances, higher accuracy for silicon diaphragm-based pressure sensors and simple temperature compensation for AFM cantilevers. © 2011 IOP Publishing Ltd.

Enikov, E. T., & Ganji, M. (2012). Numerical simulation and stability analysis of thin flexible micro film for thermotunneling application. ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 4(PARTS A AND B), 407-413.

Abstract:

Combined thermionic emission and tunneling of hot elec- Trons (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 is a term used to describe combined emission of hot electrons (thermionic emission) and tunneling of electrons through a narrow potential barrier between two surfaces (field emission). 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 be- Tween two surfaces. This presentation is focused on our effort to investigate the stability of the the thin flexible structure under electrostatic and lorenz forces opposing each other. In this pre- sentation, we report the result of numerical simulation with some mathematical simplifications. The mathematical model used for the numerical simulation is well studied in the literature. Us- ing forth-order partial differential beam equation, we studied the steady state solutions of the thermo-tunneling beam model using Galerkin method.Essential output parameters of the model in- clude 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 possi- ble operating modes: (1) symmetric deformation with negligibly small current; and (2) asymmetric mode where the B-field con- Trols the current and contact area. Under practical values for the externally applied magnetic and electric fields, it has been shown that the second mode is only possible for electrode with very low work functions, e.g. below 0.5 eV. Therefore, novel materials such as Diamond-like carbon films are likely to be essential in thermo-tunneling applications. Copyright © 2012 by ASME.

Enikov, E. T., Polyzoev, V., & Gill, J. (2011). Hardware demonstration of classical undergraduate control design methods using matlab real-time windows target environment. ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 5, 21-27.

Abstract:

Engineering education has the objective of not only presenting the scientific principles, i.e., engineering science, but also of teaching students how to apply these to real problems. Therefore, hands-on laboratories have been an integral part of the engineering curriculum since its inception [1-3]. This presentation will demonstrate the use of a novel low-cost experimental apparatus for use in a typical undergraduate course in control systems taught to mechanical engineering students, i.e. students with limited exposure to electrical engineering. A simple to use, low cost system has been designed that provides a platform for experimentation in areas from basic open loop control, to frequency domain and digital control systems. This paper presents the design of the system, and demonstrates the ability of MAT-LAB tools such as Simulink Real Time Windows Target to illustrate implementation of various aspects of control design. The system setup consists of a DC micro-motor attached to a carbon fiber rod. The angular displacement is measured with an analog potentiometer, which acts as the pivot point for the carbon fiber rod. The DC micro-motor is powered by a low cost, custom circuit board, whos H-bridge allows the motor rotate in either forward or reverse directions. Attached to the micro-motor is a small propeller, providing thrust force to rotate the pendulum about its potentiometer. The circuit board communicates to the host computer using the USB protocol, utilizing usbser.sys to create a virtual COM port. MATLAB uses the serial port object to read and write from the control board. The control board is powered through two USB ports, requiring no external power adaptor or extra cabling. This paper shows the use of feedback linearization to arrive at a system where classical linear control design methods can be used. The project was tested in a classical control systems design class offered to senior-level mechanical engineering students. Student feedback and survey data on the effectiveness of the module is also presented. Copyright © 2011 by ASME.