<p dir="ltr">Inkjet printing allows for rapid prototyping and design iteration that traditional printing methods do not. The use of inkjet printing for electronic devices has seen increased use in recent years owing to its high precision and ability to quickly test new devices. However, nearly all of this work has been done on smooth substrates with surface roughnesses on the nano scale. To further explore the capabilities of inkjet printing on rough surfaces, electrically conductive ink was printed onto a variety of solids-loaded polymer composite substrates using varied filler particle sizes with surface roughnesses on the micron scale. This work examines the necessary parameters required to print on these rough surfaces and characterizes the electrical properties of deposited ink. Electrical conductivity was demonstrated on surfaces across five distinct substrates using varied particle sizes. Further, two functional devices in the form of a heater and a strain gauge were printed and tested on these substrates. These devices showed comparable performance to commercially available devices. These findings offer improved ability to use inkjet technology on a variety of substrates and have implications in multiple fields. This demonstration of basic conductivity and advanced functionality shows the potential to continue development of complex devices and integrate them into new substrates. The optimization of printing algorithms on these rough surfaces also has significant potential to improve printability on rough surfaces and further expand capabilities.</p>

<p dir="ltr">Energetic materials (EMs) manufacturing practices have evolved little since the First and Second World Wars. Because of this, a substantial focus has recently been placed on modernizing the processes used in the production of these materials to mitigate the risk of human error and prevent the potentially fatal, and costly, consequences that exist when accidents take place. In this work, a piezoelectrically actuated inkjet printer system was used to deposit functional materials onto the surfaces of mock and live polymer-bonded EMs. The benefit to this is two-fold: (1) the material can safely be deposited remotely and (2) this high resolution method of printing can open the door to novel applications, allowing for functional elements to be integrated directly with the material. To start, composite formulation and mixing parameters were studied on a variety of mixers to better inform substrate preparation and the role that these parameters may play in a variety of substrate material properties, including local internal composition, density, quasi-static compression, and surface topography. From here, the topography and surface free energy of the surface of these materials was analyzed further to better inform ink formulation and selection. Upon observing the ink behavior at the interface, print parameters were chosen that supported the creation of continuous architectures that could function in a variety of capacities, including as resistance probes, strain gauges, heaters, spark gap igniters, and antennas.</p>