3D printing (considered by many as a transformative technology) and has been receiving significant attention in the scientific literature and the popular press.  Over the last several years, 3D printing has generated exciting business opportunities, interests, and prospects.  This rapidly evolving technology is capable of impacting many areas of Science (e.g., Physics, Chemistry and Biology), many branches of Engineering, and Medicine (including dentistry).  The ability to print (on-demand using relatively inexpensive printers) one-of-a-kind, personalized items will offer the foundation for a personalized future.  The aim of this tutorial is to provide a brief description of 3D-printing (including printing technology and materials), and to describe some selected applications.   Toward the end of the tutorial, future directions and the potential on societal and economic impacts of 3D printing will be described.

Among different types of sensors, piezoelectric sensors are of great interest due to their high sensitivity, long lifetime and fast response time. Some types of piezoelectric sensors have the ability to work in wired and wireless modes. With the advancement in flexible printed electronics, researchers have started to fabricate flexible printed piezoelectric sensors as they are low cost, conformable and have lower frequency of operation than their rigid microfabricated counterpart. However, very few researchers have successfully applied flexible printed electronics technology to develop highly sensitive piezoelectric sensor. This tutorial session will identify the key difficulties to achieve highly sensitive piezoelectric sensor. It will cover conventional materials, processes and design used for flexible printed piezoelectric sensor, their limiting factors and present emerging materials and processes that can overcome those limitations. It will also cover how new circuit topologies can improve the performance of flexible printed piezoelectric sensors. Some of the performance improvement techniques will be presented in the context acoustic wave sensor, a popular type of piezoelectric sensor. The tutorial will present some examples of high performance piezoelectric sensor from from the literature (with some from the author’s laboratory). At the end, the tutorial will allow the attendees to brainstorm on possible ideas (other than the ideas presented in the tutorial) to improve the performance of printed flexible piezoelectric sensors.

Conducting polymers are highly suitable as sensing materials for different gases, with their earliest application dating back to the 1980s.  This tutorial discusses chemical sensors based on chemical modulation of electronic properties of conducting polymers resulting from their interaction with gases. Key indicators of sensor performance including sensor response, analyte concentration, response time, and recovery time are the essential aspects of robust gas sensing. Doping and undoping play vital roles in the gas sensing mechanism of the conducting polymer sensors. The chemistry of the materials and mechanisms of interaction with gases are discussed. Conducting polymers are first introduced as chemoresistors, followed by their incorporation into organic field effect transistors (FET) that are sensitive to gases and development of Electrolyte-gated organic FET (EGOFET). Additionally, the parameters that govern selectivity of a conducting polymer to specific gases and vapours are discussed. The talk will also cover aspects of sampling, measurement and instrumentation platforms that are appropriate to the technology and will give example applications.

For decades we’ve been hearing about the promise of printing electronics directly onto any surface. However, despite significant progress in the development of inks and printing processes, reports on fully, direct-write printed electronics continue to rely on excessive thermal treatments and/or fabrication processes that are external from the printer. In this tutorial, background information on aerosol jet printing – a versatile, direct-write printing technique – will be provided. The use of nanomaterial suspensions as electronic inks will also be reviewed, including carbon nanotubes (CNTs), graphene, and hexagonal boron nitride (hBN). Then, recent progress towards print-in-place electronics will be discussed; print-in-place involves loading a substrate into a printer, printing all needed layers, then removing the substrate with electronic devices immediately ready to test. To achieve this, significant advancements were made to minimize the intermixing of printed layers, drive down sintering temperature, and achieve sufficient thin-film electrical properties. It will be shown how inks from nanoscale materials have the potential to overcome some of the major hurdles for printed devices, particularly in yielding direct-printed thin films meeting target electrical performance, air stability, and process compatibility. In addition, three attractive options for direct-write printed insulating inks will be discussed: 2D hBN, ion gel, and crystalline nanocellulose. The appropriate design of these nanomaterial-based inks can enable the printing of fully recyclable electronics, where the constituent nanomaterials can be reclaimed and reused after initial printing and use in electronic devices. Overall, this tutorial should provide: 1) background for those less familiar with aerosol jet printing and nanomaterial-based inks; and 2) recent progress on print-in-place and recyclable electronics, from transistors to diverse sensors on virtually any substrate.

Inkjet printing technology encompasses the generation, control and deposition of 10-100 um liquid drops. Besides graphic printing applications, new opportunities for inkjet printing are starting to be exploited commercially in the manufacture of high value, high precision products. The applications include flexible electronics such as sensors and logic circuits as well as 3D biological tissues and organs for regenerative medicine. This talk covers from the fundamentals of inkjet printing to the wide range of electronical and biological applications. I will begin with the introduction of inkjet printing process from ink rheology to jet formation, drop impact and drying. Next how the inkjet printing can be used to fabricate thin-film transistors with a focus on 3D-stacked transistors and circuits as an innovative route for scaling in printed electronics, followed by flexible and wearable sensor arrays. Finally, another new application of inkjet – 3D printing of living cells and biomaterials for tissue engineering and regenerative medicine will be discussed. This part of the talk will show how living cells can be ejected from micron-sized nozzle and how multiple types of cells can be patterned into liquid-filled plate with high-resolution and high-precision. The fabrication processes and applications of inkjet-printed artificial skin and lung models will be introduced.