Aerosol Jet Printing of Alumina Insulation Layer for High-Temperature Sensing Applications

Abstract

Aerosol Jet Printing (AJP) falls under the material jetting class of additive manufacturing technology. AJP employs an aerosolized stream of particles to deposit material and create precise patterns onto a variety of planar and non-planar surfaces. AJP offers several distinct advantages, including a relatively high degree of material flexibility, high micro-scale precision, and an ability to print onto virtually any exposed surface. This versatility enables diverse fabrication of a variety of micro-scale electronic components from capacitors, traces, resistors, sensors and so on. In this AJP is used to develop an electrically insulative thin-film capable of functioning at high temperatures, addressing a critical need in high performance sensing devices. A key focus of the research is the selection and development of an electrically insulative tailored for high-temperature sensing applications. Aluminium-oxide (Al2O3) was selected due to its ability to maintain reasonably high resistivity, essential for effective insulation. To formulate an ink for AJP, two synthesis pathways were explored, yielding a stable and printable ink. To enhance the ink’s properties in terms of viscosity, adhesion, and thermal stability, several additives were explored, including special particles and other chemical co-solvents. It was noted that environmental conditions had a significant effect on determining the overall final outcome of the deposited ink. The ink composition and AJP printing parameters were systematically optimized maximize printability. Electrical and mechanical testing was conducted at both room temperature and high temperatures. At room temperature, it was found that with the optimized print parameters, the insulation met the minimum requirement. High-temperature testing, however, faced challenges due to limitations in test setup, resulting in a limited dataset with mixed but promising outcomes. Further investigations are needed to confirm high temperature resistance. Mechanically, the deposited insulation met strain requirements with results further improved by refining the ink formulation and machine settings. This thesis lays a foundation for future development of robust, high-temperature insulative coatings printed via AJP.