# The Construction of a System for Four Point Probe Over a Wide Range of Temperatures

#### Abstract

The goal of this project is to measure the resistance of vanadium dioxide over a wide range of temperatures. To accomplish this we are going to create a system with three separate components to control the temperature and measure the resistance. The three components will be mechanical, electrical, and computational. The first electrical component is the temperature control circuit. This one will have two parts with the first part controlling the relay that turns the heater on and off. The second part logs the temperature through the use of a thermocouple which will let the system know if the vanadium dioxide is below or above our desired temperature and activate the first part. This temperature-control circuit will interface with code that implements a PID controller. This is a code that sums values which are proportional to our input, the integral of our input, and the derivative of our input to achieve an exact output. The second electrical component is a circuit that will measure the resistance of the vanadium dioxide. The circuit will apply a constant current and will read the changes in voltage across the vanadium dioxide as the temperature changes. It will then use these values to calculate the resistance across the vanadium dioxide at those temperatures. The mechanical component of the system will be an aluminum block that the vanadium dioxide will rest on. The heater will also be inserted into the aluminum block which will also heat up the vanadium dioxide.

Apr 13th, 11:15 AM Apr 13th, 12:30 PM

The Construction of a System for Four Point Probe Over a Wide Range of Temperatures

CNS Atrium

The goal of this project is to measure the resistance of vanadium dioxide over a wide range of temperatures. To accomplish this we are going to create a system with three separate components to control the temperature and measure the resistance. The three components will be mechanical, electrical, and computational. The first electrical component is the temperature control circuit. This one will have two parts with the first part controlling the relay that turns the heater on and off. The second part logs the temperature through the use of a thermocouple which will let the system know if the vanadium dioxide is below or above our desired temperature and activate the first part. This temperature-control circuit will interface with code that implements a PID controller. This is a code that sums values which are proportional to our input, the integral of our input, and the derivative of our input to achieve an exact output. The second electrical component is a circuit that will measure the resistance of the vanadium dioxide. The circuit will apply a constant current and will read the changes in voltage across the vanadium dioxide as the temperature changes. It will then use these values to calculate the resistance across the vanadium dioxide at those temperatures. The mechanical component of the system will be an aluminum block that the vanadium dioxide will rest on. The heater will also be inserted into the aluminum block which will also heat up the vanadium dioxide.