We present SqueezaPulse, a technique for embedding interactivity into fabricated objects using soft, passive, low-cost bellow-like structures. When a soft cavity is squeezed, air pulses travel along a flexible pipe and into a uniquely designed corrugated tube that shapes the airflow into predictable sound signatures. A microphone captures and identifies these air pulses enabling interactivity. We describe the underlying acoustic theory used to inform our design, an informal examination of the effect of different 3D-printed corrugations on air signatures, and our resulting SqueezaPulse implementation. To demonstrate and evaluate the potential of SqueezaPulse, we present four prototype applications and a small, lab-based user study (N=9). Our evaluations show that our approach is accurate across users and robust to external noise. We conclude with a discussion of limitations and future work.

We describe techniques that allow inexpensive, ultra-thin, battery-free Radio Frequency Identification (RFID) tags to be turned into simple paper input devices. We use sensing and signal processing techniques that determine how a tag is being manipulated by the user via an RFID reader and show how tags may be enhanced with a simple set of conductive traces that can be printed on paper, stencil-traced, or even hand-drawn. These traces modify the behavior of contiguous tags to serve as input devices. Our techniques provide the capability to use off-the-shelf RFID tags to sense touch, cover, overlap of tags by conductive or dielectric (insulating) materials, and tag movement trajectories. Paper prototypes can be made functional in seconds. Due to the rapid deployability and low cost of the tags used, we can create a new class of interactive paper devices that are drawn on demand for simple tasks. These capabilities allow new interactive possibilities for pop-up books and other papercraft objects.

We introduce Acoustruments: low-cost, passive, and power-less mechanisms, made from plastic, that can bring rich, tangible functionality to handheld devices. Through a structured exploration, we identified an expansive vocabulary of design primitives, providing building blocks for the construction of tangible interfaces utilizing smartphones' existing audio functionality. By combining design primitives, familiar physical mechanisms can all be constructed from passive elements. On top of these, we can create end-user applications with rich, tangible interactive functionalities. Our experiments show that Acoustruments can achieve 99% accuracy with minimal training, is robust to noise, and can be rapidly prototyped. Acoustruments adds a new method to the toolbox HCI practitioners and researchers can draw upon, while introducing a cheap and passive method for adding interactive controls to consumer products.

We explore 3D printing physical controls whose tactile response can be manipulated programmatically through pneumatic actuation. In particular, by manipulating the internal air pressure of various pneumatic elements, we can create mechanisms that require different levels of actuation force and can also change their shape. We introduce and discuss a series of example 3D printed pneumatic controls, which demonstrate the feasibility of our approach. This includes conventional controls, such as buttons, knobs and sliders, but also extends to domains such as toys and deformable interfaces. We describe the challenges that we faced and the methods that we used to overcome some of the limitations of current 3D printing technology. We conclude with example applications and thoughts on future avenues of research.

We present a technology for designing curved display surfaces that can both display information and sense two dimensions of human touch. It is based on 3D printed optics, where the surface of the display is constructed as a bundle of printed light pipes, that direct images from an arbitrary planar image source to the surface of the display. This effectively decouples the display surface and image source, allowing to iterate the design of displays without requiring changes to the complex electronics and optics of the device. In addition, the same optical elements also direct light from the surface of the display back to the image sensor allowing for touch input and proximity detection of a hand relative to the display surface. The resulting technology is effective in designing compact, efficient displays of a small size; this has been applied in the design of interactive animated eyes.

We present an approach to 3D printing custom optical elements for interactive devices labelled Printed Optics. Printed Optics enable sensing, display, and illumination elements to be directly embedded in the casing or mechanical structure of an interactive device. Using these elements, unique display surfaces, novel illumination techniques, custom optical sensors, and embedded optoelectronic components can be digitally fabricated for rapid, high fidelity, highly customized interactive devices. Printed Optics is part of our long term vision for interactive devices that are 3D printed in their entirety. In this paper we explore the possibilities for this vision afforded by fabrication of custom optical elements using today's 3D printing technology.