Fabricating entire systems with both electrical and mechanical content through on-demand 3D printing is the future for high value manufacturing. In this new paradigm, conformal and complex shapes with a diversity of materials in spatial gradients can be built layer-by-layer using hybrid Additive Manufacturing (AM). A design can be conceived in Computer Aided Design (CAD) and printed on-demand. This new integrated approach enables the fabrication of sophisticated electronics in mechanical structures by avoiding the restrictions of traditional fabrication techniques, which result in stiff, two dimensional printed circuit boards (PCB) fabricated using many disparate and wasteful processes. The integration of Additive Manufacturing (AM) combined with Direct Print (DP) micro-dispensing and robotic pick-and-place for component placement can 1) provide the capability to print-on-demand fabrication, 2) enable the use of micron-resolution cavities for press fitting electronic components and 3) integrate conductive traces for electrical interconnect between components. The fabrication freedom introduced by AM techniques such as stereolithography (SL), ultrasonic consolidation (UC), and fused deposition modeling (FDM) have only recently been explored in the context of electronics integration and 3D packaging. This paper describes a process that provides a novel approach for the fabrication of stiff conformal structures with integrated electronics and describes a prototype demonstration: a volumetrically-efficient sensor and microcontroller subsystem scheduled to launch in a CubeSat designed with the CubeFlow methodology.

Implementing electronics systems that are conformal with curved and complex surfaces is difficult if not impossible with traditional fabrication techniques, which require stiff, two dimensional printed circuit boards (PCB). Flexible copper based fabrication is currently available commercially providing conformance, but not simultaneously stiffness. Consequently, these systems are susceptible to reliability problems if bent or stretched repeatedly. The integration of Additive Manufacturing (AM) combined with Direct Print (DP) micro-dispensing can provide shapes of arbitrary and complex form which incorporate 1) miniature cavities for insetting electronic components and 2) conductive traces for electrical interconnect between components. The fabrication freedom introduced by AM techniques such as stereolithography (SL), ultrasonic consolidation (UC), and fused deposition modeling (FDM) have only recently been explored in the context of electronics integration. Advanced dispensing processes have been integrated into these systems allowing for the introduction of conductive inks to serve as electrical interconnect within intricately-detailed dielectric structures. This paper describes a process that provides a novel approach for the fabrication of stiff conformal structures with integrated electronics and describes several prototype demonstrations: a body conformal helmet insert for detection of Traumatic Brain Injury (TBI), a 3D magnetic flux sensor with LED indicators for magnitude and direction and a floating sensor capable of detecting impurities in water while maintaining orientation through density gradients.

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Applications of RFID technology are continually increasing, solving problems related with keeping track of objects and persons. For instance, nowadays the fact of knowing the precise location of a shipment is considered essential. On the other hand, antenna principles often seem complicated when they are studied the first time; but the reality is that the main concepts could be explained in a simple and practical way. Furthermore, an early contact with these concepts generates a solid understanding of the phenomena. The RFID system presented in this work is intended to be used with pre-college students, being simple enough to ensure understanding, but also showing interesting antenna designs such as the sinuous antenna. The system is easy to reproduce, using Digital Direct Manufacturing (3D printing) to build it, and convenient to teach antenna principles to students at all levels. Screen printing was the metal deposition of choice since at the high school level this process is easily implemented. Screen printing kits purchased from a craft store can be obtained for less than fifty dollars and can accommodate the antenna design “graphics”. This process can be compared to that of screen printing t-shirts replacing paint with polymer conductive ink. A sinuous antenna is used for the reader and a meandered dipole for the tag. The tag design is flexible enough to allow students to adapt it to different shapes, hence, promoting their creativity.

3-D printing, rapid prototyping, and additive manufacturing (AM) technologies are maturing to the point where direct integration of sensors into Wind Tunnel Models (WTM's) is becoming feasible. Direct integration thru rapid prototyping can enable WTM's having a larger number of enhanced measurements. Such easily integrated and ubiquitous sensor capabilities are critical to improving the correlation between model performance and CFD simulations, especially in the transonic regime where computational predictions are often lacking. Heat flux sensors have been a mainstay of aerodynamic testing due to the sensor's simplicity, conformal application, and ability to infer many phenomena such as flow separation, shock behavior, and boundary layer phenomena. Here we describe our efforts to directly print heat flux sensors onto 3-D printed WTM components. We present data to characterize these sensors in a low-speed wind tunnel and compare results to commercially available heat flux sensors. The effort addresses several challenges to 3-D printed heat flux integration including printed heat flux sensor design, printing onto curved surfaces, printing of electrical traces, and printing of electrical via's such that electrical traces can be routed on the inner surfaces of the WTM. The printed sensor's ability to detect flow separation and vortex shedding phenomena is demonstrated. The printed sensors are also shown to have comparable performance to commercially available sensors fabricated using traditional methods.