## Mechanical & Materials Engineering, Department of

#### First Advisor

Sidy Ndao

#### Date of this Version

Fall 12-2019

#### Citation

Ahmed Hamed, "NanoThermoMechanical Logic Gates for Thermal Computing," University of Nebraska-Lincoln Doctoral Dissertation, 2019.

#### Abstract

Limited performance and reliability of electronic devices at extreme temperatures, intensive electromagnetic fields, and radiation found in space exploration missions (i.e., Venus & Jupiter planetary exploration, and heliophysics missions) and earth-based applications require the development of alternative computing technologies. Thermal computing, data processing based on heat instead of electricity, is proposed as a practical alternative and opens a new scientific area at the interface between thermal and computational sciences.

We successfully developed thermal AND, OR and NOT logic gates, achieved through the coupling between near-field thermal radiation and MEMS thermal actuation. In the process, we developed two novel non-linear thermal expansion designs of microstructure silicon V-shaped chevron beams which were required to achieve the desired thermal AND gate operation. The successful design paves the way to develop full thermal logic circuits, so we show the design and simulation of a thermal calculator based on binary mathematical computations. This thermal calculator was able to perform the addition of two decimal numbers.

Furthermore, we introduce the microfabrication and characterization of the thermal AND and OR logic gates. The thermal AND logic gate consists of two non-linear mechanisms using novel and ingenious chevron mechanisms consisting of spring-assisted reduction and cascading chevrons amplification for the reducing and the amplification mechanisms, respectively. The experimental results show that we achieved non-linearity ratios of thermal expansion of 0.36 and 3.06 for the reducing and the amplification mechanisms, respectively. For the characterization of thermal AND logic gate, for the case when the two inputs were at (i.e., 0,0 case), we achieved an effectiveness of 10.7 % at a heat source temperature of 1549 K. For the thermal OR logic gate, for the cases of (1,0) and (0,1), we achieved an effectiveness of 25.3 % and 23.2 % at an input temperature of 1324 K and 1391 K, respectively. These results are significant breakthroughs in the field of thermal computation science and technology as they demonstrate thermal computing at high temperatures based on demonstrated and easy to manufacture NanoThermoMechanical logic gates.

Advisor: Sidy Ndao

*Amplification Mechanism Video*

NanoThermoMechanical AND and OR Logic Gates - Reducing Mechanism Video.mp4 (21321 kB)

*Reducing Mechanism Video*

NanoThermoMechanical AND and OR Logic Gates - AND All 5 deg case 00.mp4 (13517 kB)

*AND All 5 deg case 00*

NanoThermoMechanical AND and OR Logic Gates - AND All 5 deg case 10.mp4 (5302 kB)

*AND All 5 deg case 10*

NanoThermoMechanical AND and OR Logic Gates - OR All 6 6_5 deg case 01.mp4 (11001 kB)

## Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Mechanical Engineering and Applied Mechanics (Thermal Science), Under the Supervision of Professor Sidy Ndao. Lincoln, Nebraska: December, 2019

Copyright 2019 Ahmed Hamed