Ahsan Mian, Ph.D. (Advisor); Raghu Srinivasan, Ph.D. (Committee Member); Hong Huang, Ph.D. (Committee Member); Henry D. Young, Ph.D. (Committee Member); Amir Alfalahi, Ph.D. (Committee Member)
Doctor of Philosophy (PhD)
Different additive manufacturing (AM) methods including fused deposition modeling (FDM) and piezoelectrical drop on demand (DOD) inkjet printing have been used in printed electronics for easy production, easy integration, better performance, and low cost. These methods have been used in producing everyday smart printed electronics such as conformal antennas (planner and non-planar antennas), sensors, actuators, and solar cells created on flexible and rigid substrates. The performance of printed electronics strongly depends on printing techniques and printing resolution that enhance their electrical and mechanical properties. In this dissertation, 3D and surface printing techniques were used to enhance the performance of printed electronics devices fabricated on rigid and flexible substrates. First, fused deposition modeling (FDM) technique was used to study the effect of 3D printed heterogeneous substrates on radio frequency response of microstrip patch antennas. Microstrip patch antennas created on acrylonitrile butadiene styrene (ABS) substrates that were designed by 3D CAD design software (SOLIDWORKS) with dimension 50mm x 50mm x 5mm and fabricated with different machine infill densities 25%, 50%, and 75% using FDM 3D printer. Then, 3D X-ray microscope was used to measure the actual volume fraction and construct equivalent simulations for series and parallel equivalent dielectrics constant. The patch antennas were tested for resonant frequency using a vector network analyzer (VNA) combined with ANSYS-HFSS simulation that was developed based on the permittivity anisotropy in 3D printed heterogeneous substrates to estimate the bulk permittivity of ABS material and study the effect of varying the dielectric constant in lateral and thickness direction. Also, microstrip patch antenna with dimension 30mm x 25mm, was modeled on polydimethylsiloxane (PDMS) substrate with the same dimension of ABS substrate and analyzed for resonant frequency using Ansoft HFSS and COMSOL Multiphysics software. Then, COMSOL Multi-physics software was used to study the behavior of the microstrip patch antenna under different values of compression and bending loads to check the feasibility of using the microstrip patch antenna as a passive sensor to detect the strain in the structure wirelessly. Second, piezoelectrical drop on demand (DOD) inkjet printing was used to print uniform and even high conductive nanosilver ink on rigid and flexible substrates. For surface printing, Jetlab 4xl was used to print lines of high conductive nanosilver ink (UTDAg) on semicrystalline polyether ether ketone (PEEK) substrate using fly mode printing with burst. Then, optimal bipolar waveform was generated at proper jetting parameters to generate ideal droplet in term of velocity, size, and uniformity. The ideal droplet was ejected at different drop spacing and stage velocity to print uniform and even lines. Physical and adhesion characteristics of the printed lines were performed by optical microscopy, scanning electron microscopy, surface profilometry, and soak tests. Also, the effect of high stage velocity printing on the spread behavior of ejected droplet with different droplet spacing on Kapton substrate was studied by printing lines using two bipolar waveforms. The resistance of printed lines were measured at different curing temperature. Finally, the effect of driving waveforms at different jetting parameters on the size and velocity of generated droplet was investigated using smartink (nanosilver ink) produced by Genes’Ink. A new method was developed to measure the size of the generated droplet and recognize weather the droplet has a spherical or an elliptical shape by using Python programming and the result compared with Aphelion imaging software. Finally, lines printed at three waveform voltages on PEEK and glass substrates.
Year Degree Awarded
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