Droplet based microfluidics (digital microfluidics) with Electrowetting on dielectric (EWOD) has gained popularity with the promise of being technology for a true lab-on-chip device with applications spanning across assays/library prep, next-gen sequencing and point-of-care diagnostics. Most electrowetting device architecture are linear electrode arrays with a shared path for droplets, imposing serious limitations -- cross contamination and limited number of parallel operations. Our work is in addressing these issues through large 2D grid arrays with direct addressability providing flexible programmability. Scaling electrowetting to larger arrays still remains a challenge due to complex and expensive cleanroom fabrication of microfluidic devices. We take the approach of using inexpensive PCB manufacturing, investigate challenges and solutions for scaling electrowetting to large area droplet manipulation. PCB manufactured electrowetting arrays impose many challenges due to the irregularities from process and materials used. These challenges generally relate to preparing the surface that interfaces with droplets -- a dielectric material on the electrodes and the top most hydrophobic coating that interfaces with the droplets. A requirement for robust droplet manipulation with EWOD is thin (<10um) hydrophobic dielectric material which does not break down at droplet actuation voltages (AC/DC, 60V to 200V) and has a no droplet pinning. For this, we engineered materials specifically for large area PCBs. Traditionally, digital microfluidic devices sandwich droplets between two plates and have focussed on sub-microliter droplet volumes. In our approach, droplets are on an open surface with which we are able to manipulate droplets in microliter and milliliter volumes. With milliliter droplet manipulation ability on our electrowetting device, we demonstrate “digital millifluidics”. Finally, we report the performance of our device and to motivate the need for large open arrays we show an example of running multiple parallel biological experiments.

We present a design exploration on how water based droplets in our everyday environment can become interactive elements. For this exploration, we use electrowetting-on-dielectric (EWOD) technology as the underlying mechanism to precisely control motion of droplets. EWOD technology provides a means to precisely transport, merge, mix and split water based droplets and has been widely explored for automating biological experiments in industrial 1 and research settings 2. More recently, it has been explored for DIY Biology applications. In our exploration we integrate EWOD devices into a range of everyday objects and scenarios to show how programmable water droplets can be used as information displays, interaction medium for painting and personal communication.

Printflatables is a design and fabrication system for human-scale, functional and dynamic inflatable objects. We use inextensible thermoplastic fabric as the raw material with the key principle of introducing folds and thermal sealing. Upon inflation, the sealed object takes the expected three dimensional shape. The workflow begins with the user specifying an intended 3D model which is decomposed to two dimensional fabrication geometry. This forms the input for a numerically controlled thermal contact iron that seals layers of thermoplastic fabric. In this paper, we discuss the system design in detail, the pneumatic primitives that this technique enables and merits of being able to make large, functional and dynamic pneumatic artifacts. We demonstrate the design output through multiple objects which could motivate fabrication of inflatable media and pressure-based interfaces.

In this paper, we present AnimaStage: a hands-on animated craft platform based on an actuated stage. Utilizing a pin-based shape changing display, users can animate their crafts made from various materials. Through this system, we intend to lower the barrier for artists and designers to create actuated objects and to contribute to interaction design using shape changing interfaces for inter-material interactions. We introduce a three-phase design process for AnimaStage with examples of animated crafts. We implemented the system with several control modalities that allow users to manipulate the motion of the crafts so that they could easily explore their desired motion through an iterative process. To complement the animated crafts, dynamic landscapes can also be rendered. We conducted a user study to observe the subject and process by which people make crafts using AnimaStage. We invited participants with different backgrounds to design and create crafts using multiple materials and craft techniques. A variety of outcomes and application spaces were found in this study.

Printflatables is a design and fabrication system for human-scale, functional and dynamic inflatable objects. We use inextensible thermoplastic fabric as the raw material with the key principle of introducing folds and thermal sealing. Upon inflation, the sealed object takes the expected three dimensional shape. The workflow begins with the user specifying an intended 3D model which is decomposed to two dimensional fabrication geometry. This forms the input for a numerically controlled thermal contact iron that seals layers of thermoplastic fabric. In this paper, we discuss the system design in detail, the pneumatic primitives that this technique enables and merits of being able to make large, functional and dynamic pneumatic artifacts. We demonstrate the design output through multiple objects which could motivate fabrication of inflatable media and pressure-based interfaces.

The ACM Symposium on User Interface Software and Technology (UIST) is the premier forum for innovations in human-computer interfaces. This year, we curated more than 40 demonstrations, aimed to allow conference attendees to look, touch, and witness new and inspiring technologies live. Here, we selected four projects that showcase the very best in the community. Chris Harrison and Nicolai Marquardt, UIST 2015 Demo Committee Chairs

Based on kinesiology research demonstrating that translation and rotation are inseparable actions in the physical world, we present Mushaca, a 3-degrees-of-freedom mouse that senses rotation in addition to traditional planar position. We present an optical realization of the Mushaca device based on two optical sensors and then evaluate the device through a series of controlled experiments. Our results show that rotation is indeed a useful input modality for a pointing device, and also give some insight into how users perceive the changing coordinate system of the rotating mouse and adapt to this change through kinesthetic learning.

Physical sketching of 3D wireframe models, using a hand-held plastic extruder, allows users to explore the design space of 3D models efficiently. Unfortunately, the scale of these devices limits users' design explorations to small-scale objects. We present protopiper, a computer aided, hand-held fabrication device, that allows users to sketch room-sized objects at actual scale. The key idea behind protopiper is that it forms adhesive tape into tubes as its main building material, rather than extruded plastic or photopolymer lines. Since the resulting tubes are hollow they offer excellent strength-to-weight ratio, thus scale well to large structures. Since the tape is pre-coated with adhesive it allows connecting tubes quickly, unlike extruded plastic that would require heating and cooling in the kilowatt range. We demonstrate protopiper's use through several demo objects, ranging from more constructive objects, such as furniture, to more decorative objects, such as statues. In our exploratory user study, 16 participants created objects based on their own ideas. They rated the device as being "useful for creative exploration", "its ability to sketch at actual scale helped judge fit", and "fun to use."

We present "Level-Ups", computer-controlled stilts that allow virtual reality users to experience walking up and down steps. Each Level-Up unit is a self-contained device worn like a boot. Its main functional element is a vertical actuation mechanism mounted to the bottom of the boot that extends vertically. Unlike traditional solutions that are integrated with locomotion devices, Level-Ups allow users to walk around freely ("real-walking"). We present Level-Ups in a demo environment based on a head-mounted display, optical motion capture, and integrated with two different game engines. In a user study, participants rated the realism of stepping onto objects 6.0 out of 7.0 when wearing Level-Ups compared to 3.5 without.

Laser cutters are useful for rapid prototyping because they are fast. However, they only produce planar 2D geometry. One approach to creating non-planar objects is to cut the object in horizontal slices and to stack and glue them. This approach, however, requires manual effort for the assembly and time for the glue to set, defeating the purpose of using a fast fabrication tool. We propose eliminating the assembly step with our system LaserStacker. The key idea is to use the laser cutter to not only cut but also to weld. Users place not one acrylic sheet, but a stack of acrylic sheets into their cutter. In a single process, LaserStacker cuts each individual layer to shape (through all layers above it), welds layers by melting material at their interface, and heals undesired cuts in higher layers. When users take out the object from the laser cutter, it is already assembled. To allow users to model stacked objects efficiently, we built an extension to a commercial 3D editor (SketchUp) that provides tools for defining which parts should be connected and which remain loose. When users hit the export button, LaserStacker converts the 3D model into cutting, welding, and healing instructions for the laser cutter. We show how LaserStacker does not only allow making static objects, such as architectural models, but also objects with moving parts and simple mechanisms, such as scissors, a simple pinball machine, and a mechanical toy with gears.