Date of Graduation

Spring 2015

Document Type

Honors Research Project

Degree Name

Bachelor of Science

Major

Chemical Engineering

Research Sponsor

Dr. Chelsea Monty

First Reader

Dr. Edward Evans

Second Reader

Dr. Gang Chen

Abstract

Abstract

The purpose of this honors project is to construct and test temperature detectors, which can be used for the advancement of exercise devices, prosthetic sockets, or medical applications. Resistance Temperature Detectors (RTDs) are an effective way to measure temperature due to the dependence of the RTD material’s resistance on temperature. The focus of this project was to develop an RTD for prosthetic socket or exercise applications, where the RTD is in close contact with the skin of the user. Generally, RTDs are constructed from platinum, copper, or nickel. However, metal RTDs have a tendency to be large and rigid, making them uncomfortable for the user. The idea for this project stems from the need for a temperature device that does not create a pressure point within the liner or shoe. Rigid temperature detectors cause pressure points, which causes wear and sores on the user, but the development of a fabric-like sensor would minimize such problems due to the thin, soft, flexible characteristics of the fabric-like RTD. A solution may have been found by adhering carbon nanotubes (CNTs) to a polymer scaffold. This project will explore the effect of varying the polymer scaffold (nylon-6 concentration in electrospinning solution), which varies the fiber diameter of the polymer, the amount of MWCNTs, and the amount and type of oxidant used before polymerization in order to create a more effective RTD of this type. This project is half of the design of experiments involving nylon-6 only. The second part of the DOE will adjust the same parameters, but use polyurethane as the scaffold rather than nylon-6 and will be completed at a later time.

A model was fitted to the data to predict temperature based on resistance. This model was compared to measured data from sensor 24A-A. Sensor 24A-A was chosen because it produced the best responses to temperature change; it displayed a linear IV curve and minimal drift and responded quickly to temperature change with minimal noise and also stabilized quickly. The average temperature difference between the model and the actual data of the entire data set was 5.66%, approximately a 1.93°C difference. The results from the parameter dependence graphs showed a possible negative correlation between percent hysteresis and MWCNT loading as well as showing a negative relation between α-value and polymer weight percent. The resistance change of both up and down ramps also appears to have a weal negative relation to polymer weight percent. The percent hysteresis graph also shows a possible positive correlation to FeCl3 oxidant concentration. More analysis needs to be conducted on these aspects in order to conclude whether a correlation actually exists between these parameters.

Sensors whose resistance did not respond to temperature will be further analyzed using SEM and conductive AFM. These sensors, though non-responsive to temperature, may still respond to humidity changes, which can also be further investigated. Also, further investigation is required to determine if surfactant deposits on the MWCNTs and if so, what amount of surfactant deposits and what the effects are of this deposition.

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