Sensors are extremely valuable to this world. Without sensors, we would not be able to live as we do in this data-driven environment. Therefore, finding new ways to measure the matter around us is a continuous process. In this work, an addition to the new sensors is attempted, using materials that can withstand the most extreme circumstances. This work describes the process of designing, simulating, producing, measuring and validating a pressure sensor based on LPCVD Silicon Carbide.
The created sensor should be modular and back-end-of-line compatible. In addition, the sensor should measure pressures from 80Pa up to 1MPa at temperatures from room temperature to 600°C. Because of a favourable reaction to high temperatures, a capacitive sensor type that uses a sealed membrane for absolute pressure measurements is chosen.
Due to the large pressure range, the design has been split into three distinct parts, each with its specialised pressure range. A low-range for 80Pa to 100kPa, a mid-range sensor for 100kPa to 300kPa and a high-range sensor for 300kPa to 1MPa. To compensate for the nonlinearity in the device, two approaches are taken. One method splits the bottom electrodes, generating a more linear output with the correct division. This approach is used for low-and-mid-pressure devices. The other approach uses touch mode to decrease nonlinearity. After the membrane touches the bottom contact, a linear range is found. This approach is taken for the high-pressure device.
A flowchart has been developed based on the necessary layers to create the sensors. Using this flowchart, masks have been designed. During production, the process was adjusted, as delamination of the dielectric layer was observed. In addition, because of difficulty with sealing, the membrane is thicker than the original design.
During production, buckling of the membranes was observed. This causes the sensors to behave differently compared to the simulations. One effect the buckling may have caused is the reaction to temperature. This is opposite to the simulations. In addition, subjecting the sensors to a vacuum also causes behaviour opposite to what was intended. When high pressure is applied, the sensors do work as intended. Due to the design alterations and buckling effect, the sensors are less sensitive to pressure than intended. The best sensor has a sensitivity of 0.025 f F/100Pa compared to the designed 0.3 f F/100Pa. However, the output of the sensor is linear without needing the designed compensation techniques.

Wide band gap semiconductor has attracted significant industrial interest over the past decade with its superior properties: such as high critical electrical field, high thermal conductivity andwide band gap. Meanwhile many industries operating in harsh environments have long had demands for sensing solutions that function at high temperature. Current commercially available silicon-based temperature sensing IC has measure range limited to 155°C . This research work aims to develop a temperature sensor based on 4H silicon carbide with pronounced higher measurement range but comparable linearity. Furthermore, this work introduces silicon carbide based bipolar junction transistor (BJT) technology in the Else Kooi Lab (EKL).
Ratio-metric measurement technique from CMOS technology is adapted to eliminate PN diode and BJT’s non-linearity as a temperature sensor; and devices are implemented experimentally on epitaxial 4H-silicon carbide wafers in the EKL.
The characterization data shows that diode version sensor operates to 400 °C with a R2 value of 0.9963, the sensitivity under 1 mA constant current source is 4.8mV/°C . The BJT version operates to 200 °C with a R2 of 0.9965. In the future the sensor’s integration with pressure, gas, and other types of sensing solutions can provide a comprehensive sensing package. Such a package can be used to predict life time of critical components in harsh environment installations; and hence reduce the maintenance cost. Examples
of application scenarios include oil&gas exploration, industrial furnaces, geothermal extraction,and so on.

The goal of this bachelor thesis is to develop a control system that controls the temperature of a microthruster. This system also needs to acquire data for research. The microthruster contains a resistor that is used both as a heater and as a sensor. To facilitate the acquisition of data and the testing of the control system, a lab setup with a Keithley 2450 SourceMeter power supply was used. LabVIEW was used to control the power supply and to execute the control algorithms. The final system consists of a microcontroller that runs the control algorithms based on proportional-integral-derivative (PID) control developed in this thesis. The PID values can be adapted with use of the graphical user interface (GUI). A read-out circuit and current supply will be part of the integrated system. These circuits will be developed by other groups that are part of this bachelor project.

This thesis presents the design of an accurate current source for MEMS vaporizing liquid microthrusters. An analysis of different power supplies is presented. The design choices leading to the implemented current sink topology is given. The main components, which are an op-amp, a MOSFET and a resistor, are analyzed extensively. System integration tests showed that the current source worked adequately. The current source has also been tested separately and the imposed accuracy requirement is not met. The reason for this has to be further investigated, as there are many potential sources of errors which can cause deviations in the order of microampere. Lastly, several recommendations are given for improving the system.

The objective of the project is to design a system which can control the temperature of a va-porizing liquid microthruster (VLM). The liquid in a VLM is heated using a heater resistor.This resistor will be used to both heat the liquid and measure the temperature.In this thesis the subsystem responsible for the measurements and the conversion of the mea-sured signals to the digital domain will be discussed. We propose a method where short measure-ment current pulses of a fixed amplitude are applied to the heater resistor. As an optimization,these pulses are omitted when a certain current threshold has been met.Results show that the system can measure temperature with±1◦C accuracy, however more fullsystem measurements are required to ensure functionality as a whole.