DuoTouch is a passive attachment for capacitive touch panels that adds tangible input while minimizing content occlusion and loss of input area. It uses two contact footprints and two traces to encode motion as binary sequences and runs on unmodified devices through standard touch APIs. We present two configurations with paired decoders: an aligned configuration that maps fixed-length codes to discrete commands and a phase-shifted configuration that estimates direction and distance from relative timing. To characterize the system’s reliability, we derive a sampling-limited bound that links actuation speed, internal trace width, and device touch sampling rate. Through technical evaluations on a smartphone and a touchpad, we report performance metrics that describe the relationship between these parameters and decoding accuracy. Finally, we demonstrate the versatility of DuoTouch by embedding the mechanism into various form factors, including a hand strap, a phone ring holder, and touchpad add-ons.

We propose an approach to detect finger hover inputs on a smartphone screen using corneal reflection images captured by the device’s built-in front camera. This method requires no external sensors or hardware, enabling hover input detection in the near-screen space that is not directly visible to the camera. By leveraging a convolutional neural network (CNN), we estimate the two-dimensional position of a hovering finger and classify it into a predefined screen grid. Experimental results show that our model achieves approximately 95% accuracy for coarse grids and maintains over 88% accuracy for finer divisions. Furthermore, our system demonstrates real-time processing capability with an end-to-end latency of approximately 22 ms on a standard smartphone. These findings highlight the practical feasibility of camera-only hover sensing and suggest a wide range of touchless interaction applications, enabling touchless interaction when touch is undesirable, pre-touch UI adaptation, and accessibility support on commodity mobile devices.

Double-tap-to-zoom is a common gesture on mobile devices, but often applies a fixed scale factor, requiring users to manually adjust zoom levels via pinch gestures to achieve comfortable readability. This limitation is particularly critical for text content, especially for users with diverse visual needs. We propose a target-aware zooming technique that dynamically adjusts the scale factor based on content and user preferences, positioning the tapped text at a preferred screen location. A crowdsourced study (N = 269) identified design requirements, followed by quantitative (N = 12) and qualitative (N = 16) user studies demonstrating improved readability and reductions in task time, manual adjustments, and physical workload. Based on the results of these studies, we incorporated a context-aware feature that adjusts text size according to factors such as vision correction. This technique enhances usability without introducing new interaction methods, enabling more efficient navigation and improved reading experiences across diverse user needs and content formats.

Understanding smartphone users’ grasp postures can improve the mobile interaction experience; for instance, the user interface (UI) layout can be dynamically adjusted based on the detected grasp. In our previous work, we introduced ReflecTouch, a grasp posture detection method that leverages corneal reflection images captured by the front camera. Building on this, we conducted a follow-up study using crowdsourced experiments in uncontrolled, in-the-wild environments. Based on the results, we discuss design considerations and practical strategies, including recommendations for integrating ReflecTouch with complementary sensing modalities, such as touch and IMU-based methods, to enhance the model’s accuracy in real-world settings.

We present FoodSkin, a technique for adding interactive elements to foods by implementing edible circuits on the surface of the food. The circuit is easily fabricated using commercially available materials. Existing approaches to enhance the eating experience, such as presenting an electrical taste by making food part of an electronic circuit, are challenging to apply to foods with low water content due to their low conductivity. Our technique enables the integration of dry foods into an electronic circuit and provides displaying (e.g., smell or taste) and sensing (e.g., eating activity) functionalities. We describe our fabrication technique with a library of food materials that we can utilize, evaluate the conductivity and adhesion of the gold-leaf traces, introduce demonstrative applications, and conclude with a workshop we conducted to evaluate the accessibility of our technique. FoodSkin enriches the design space for the computer-augmented eating experience by enabling the digital fabrication of electronics on versatile materials, surfaces, and shapes of foods.

Virtual meeting tools, such as Zoom, can sometimes lead to inadvertently sharing private information through screen sharing features. We conducted fundamental investigations on what concerns and strategies users have for protecting their privacy. The results indicate that while most users take actions to protect their privacy before or during meetings, a significant number of users also reported experiences with inadvertent information sharing. We also found that users avoid sharing not only personal data, such as usernames, but also information that could reveal their interests and activities, such as browsing histories or personalized recommendations. Thus, we propose a system that automatically occludes areas that users do not want to share to facilitate the management of privacy during screen sharing. We conducted a data collection experiment to construct a deep learning model to detect the areas that users do not want to share with others. We implemented our system by using this model to protect information in real time during screen sharing in virtual meeting tools.

We present ShiftTouch, an attachment-type passive interface that provides multiple inputs for capacitive touchscreens with minimal screen occlusion. ShiftTouch utilizes multiple linear electrodes to control the fine displacement of the touch position. The touch input is activated under the electrodes when several adjacent electrodes are grounded simultaneously. Each input area shares several electrodes with neighboring input areas, and the touchscreen identifies each one by detecting the fine displacement of the touch position. ShiftTouch can effectively reduce the occlusion area while inheriting the advantages of existing touch extension interfaces, which are battery-free, freely detachable, and easy to construct. Depending on the number of inputs to implement, ShiftTouch can alleviate screen occlusion by up to 80.5% compared to existing approaches using finger-sized electrodes.

Touch surfaces are widely utilized for smartphones, tablet PCs, and laptops (touchpad), and single and double taps are the most basic and common operations on them. The detection of single or double taps causes the single-tap latency problem, which creates a bottleneck in terms of the sensitivity of touch inputs. To reduce the single-tap latency, we propose a novel machine-learning-based tap prediction method called PredicTaps. Our method predicts whether a detected tap is a single tap or the first contact of a double tap without having to wait for the hundreds of milliseconds conventionally required. We present three evaluations and one user evaluation that demonstrate its broad applicability and usability for various tap situations on two form factors (touchpad and smartphone). The results showed PredicTaps reduces the single-tap latency from 150--500 ms to 12 ms on laptops and to 17.6 ms on smartphones without reducing usability.

This pictorial presents a novel method to render color patterns using electrolysis applied onto open wet surfaces. By implementing electrodes within a wet object and electrifying them, electrolysis can occur and generate ions. We designed a color-forming display using color indicators reacting with such ions. This method can display patterns according to the shape of the electrode. By reversing the polarity of the electrodes and generating reversed-polarity ions, it is possible to fade the existing pattern and display a contrasting color. The proposed method does not require moving parts; thus, it is low cost and easy to compact. Also, some foods containing pH-reactive substances can be used as a display medium. Therefore, the proposed method can realize an information display using various objects common in everyday life, such as decor or food.

By sensing how a user is holding a smartphone, adaptive user interfaces are possible such as those that automatically switch the displayed content and position of graphical user interface (GUI) components following how the phone is being held. We propose ReflecTouch, a novel method for detecting how a smartphone is being held by capturing images of the smartphone screen reflected on the cornea with a built-in front camera. In these images, the areas where the user places their fingers on the screen appear as shadows, which makes it possible to estimate the grasp posture. Since most smartphones have a front camera, this method can be used regardless of the device model; in addition, no additional sensor or hardware is required. We conducted data collection experiments to verify the classification accuracy of the proposed method for six different grasp postures, and the accuracy was 85%.

Due to its natural warmth, wood is frequently used to produce touchable objects such as furniture and signboards. Laser cutting machines are becoming common in personal wood processing to cut and engrave wood. In this paper, we propose a method and workflow for producing various sensors and electrical circuits for interactive devices by partially carbonizing the wood surface with a laser cutting machine. Similar to wiring on a conventional printed circuit board (PCB), the carbonized part functions as a conductive electrical path. A method for creating electronic circuits and sensors made of carbon graphene on botanical materials has been proposed. This technique makes use of a raster-scanning femtosecond (fs) laser, which is less common for personal fabrication than a constant-wave (CW) laser. Moreover, raster-scanning requires a substantial amount of time to create a circuit that is mainly made of conductive lines. This paper extends the method with a defocused vector-scanning CW laser beam and reduces the time and cost required for fabrication. The proposed method uses an affordable CW laser cutter to fabricate an electrical circuit, including touch sensors, damage sensors, and load sensors on wood boards. The circuit can be easily connected to traditional PCBs and electric parts such as one-board microcomputers using metal screws and nails typically used in DIY woodworking. We develop ease of use software design tool that supports the creation and fabrication of carbon paths. In addition, we report on a series of investigations, including optimizing wood materials and laser parameters to establish design guidelines.

In this pictorial, we propose an approach to integrate electronics into a paper-woven craft. A paper-woven structure is formed by alternately and orthogonally weaving paper strips. The key idea is to add conductive layers to these strips by printing or transferring conductive materials. Our approach enables us to form the skeleton of an object and its wiring and sensor arrangement simultaneously. We explore the creative space of this approach, i.e., integrating functions such as sensing, display, and sound amplification into objects, for leveraging the paper-woven structure. We also outline the workflow of the approach, introduce a design support tool, and discuss example applications that combine the electronic-enabled functionality and woven structure.

We propose a novel phone-case-shaped interface named TetraForce, which enables four types of force input consisting of two force directions (i.e., pressure force and shear force) and two force-applied surfaces (i.e., touch surface and back surface) in a single device. Force detection is achieved using the smartphone's built-in magnetometer (and supplementary accelerometer and gyro sensor) by estimating the displacement of a magnet attached to a 3-DoF passively movable panel at the back. We conducted a user study (N=12) to investigate the fundamental user performance by our interface and demonstrated that the input was detected as intended with a success rate of 97.4% on average for all four input types. We further conducted an ideation workshop with people who were involved in human-computer interaction (N=12) to explore possible applications of this interface, and we obtained 137 ideas for applications using individual input types and 51 possible scenarios using them in combination. Organizing these ideas reveals the advantages of each input type and suggests that our interface is useful for applications that require complex operations and that it can improve intuitiveness through elastic feedback.

We propose TiltChair, an actuated office chair that physically manipulates the user’s posture by actively inclining the chair’s seat to address problems associated with prolonged sitting. The system controls the inclination angle and motion speed with the aim of achieving manipulative but unobtrusive posture guidance. To demonstrate its potential, we first built a prototype of TiltChair with a seat that could be tilted by pneumatic control. We then investigated the effects of the seat’s inclination angle and motions on task performance and overall sitting experience through two experiments. The results show that the inclination angle mainly affects the difficulty of maintaining one’s posture, while the motion speed affected the conspicuousness and subjective acceptability of the motion. However, these seating conditions did not affect objective task performance. Based on these results, we propose a design space for facilitating effective seat-inclination behavior using the three dimensions of angle, speed, and continuity. Furthermore, we discuss promising applications.

We present LightTouch, a 3D-printed passive gadget to enhance touch interactions on unmodified capacitive touchscreens. The LightTouch gadgets simulate finger operations such as tapping, swiping, and multi-touch gestures by means of conductive materials and light-dependent resistors (LDR) embedded in the object. The touchscreen emits visible light and the LDR senses the level of this light, which changes its resistance value. By controlling the screen brightness, it intentionally connects or disconnects the path between the GND and the touchscreen, thus allowing the touch inputs to be controlled. In contrast to conventional physical extensions for touchscreens, our technique requires neither continuous finger contact on the conductive part nor the use of batteries. As such, it opens up new possibilities for touchscreen interactions beyond the simple automation of touch inputs, such as establishing a communication channel between devices, enhancing the trackability of tangibles, and inter-application operations.

Research was conducted on a digital information display using electrolysis bubbles. Although the research mainly focused on information displays in daily life, the ephemerality of bubbles is also a promising method for dynamic art installations. In this paper, we present two novel artworks using this electrolysis bubble display mechanism. First, we present “UTAKATA,” a ticker-like bubble display, using a running-water channel. Seven electrodes are placed linearly on the channel bed, and they generate text messages using bubble dots that drift toward the lower end of the channel. Second, we present the “Bubble Mirror,” which is a water pan with a camera that captures a visitor’s face and displays it using electrolysis bubbles as pixels. Facial images with six levels of grayscales are displayed on the water surface using 32 × 32 electrodes. We evaluated the output properties of these configurations and discuss the results obtained.

Drilling teeth is a significant technique for dental learners. However, the existing VR tooth drill training simulators are physically large and costly, which cannot be used at home or classroom for a private study. This work presents a novel low-cost mobile VR dental simulator using off-the-shelf devices, including a mobile HMD and a stylus smartphone. In this system, a 3D-printed physical teeth prop is placed on an EMR stylus smartphone where its stylus tracks the tip position of a physical drill. Unlike existing solutions using haptic/force devices, our approach involving physical contact between the prop and drill tip enables the user’s natural teeth hardness sensation. The use of smartphone stylus would enable significantly more accurate drill position sensing around the teeth than HMD’s accompanying controllers. We also developed VR software to simulate tooth drilling on this setup. This demo will show how our new mobile simulator offers a realistic feeling of drilling teeth.

We propose a method for controlling a device that draws letters and illustrations on large, flat surfaces. Similarly to conventional inkjet printers, the device ejects a volume of water from its nozzle, with the water droplets then forming dots on surfaces such as soil, concrete, and sand. Both the direction of the nozzle and the water pressure can be controlled to enable the device to draw arbitrary two-dimensional patterns within a semicircular region with a radius of six meters. The device can draw letters and illustrations. We have investigated the pressure, the shape of the nozzle, and droplet size in order to avoid further division of the droplets into even smaller droplets while traversing the air. In this paper, we introduce the mechanism of this device and demonstrate how a user can take advantage of this new drawing tool.

In this paper, we investigated how "lying down'' body postures affected the use of the smartphone user interface (UI) design. Extending previous research that studied body postures, handgrips, and the movement of the smartphone. We have done this in three steps; (1) An online survey that examined what type of lying down postures, participants, utilized when operating a smartphone; (2) We broke down these lying down postures in terms of body angle (i.e., users facing down, facing up, and on their side) and body support; (3) We conducted an experiment questioning the effects that these body angles and body supports had on the participants' handgrips. What we found was that the smartphone moves the most (is the most unstable) in the "facing up (with support)'' condition. Additionally, we discovered that the participants preferred body posture was those that produced the least amount of motion (more stability) with their smartphones.

We propose a 3D-printed interface, CAPath, in which conductive contact points are in a grid layout. This structure allows not only specific inputs (e.g., scrolling or pinching) but also general 2D inputs and gestures that fully leverage the "touch surface." We provide the requirements to fabricate the interface and implement a designing system to generate 3D objects in the conductive grid structure. The CAPath interface can be utilized in the uniquely shaped interfaces and opens up further application fields that cannot currently be accessed with existing passive touch extensions. Our contributions also include an evaluation for the recognition accuracy of the touch operations with the implemented interfaces. The results show that our technique is promising to fabricate customizable touch-sensitive interactive objects.

We propose "Ohmic-Sticker'', a novel force-to-motion type input device to extend capacitive touch surfaces. It realizes various types of force-sensitive inputs by simply attaching on to commercial touchpads or touchscreens. A simple force-sensitive-resistor (FSR)-based structure enables thin (less than 2 mm) form factors and battery-less operation. The applied force vector is detected as the leakage current from the corresponding touch surface electrodes by using Ohmic-Touch technology. Ohmic-Sticker can be used for adding force-sensitive interactions to touch surfaces, such as analog push buttons, TrackPoint-like devices, and full 6 DoF controllers for navigating virtual spaces. In this paper, we report a series of investigations on the design requirements of Ohmic-Sticker and some prototypes.We also evaluate the performance of Ohmic-Sticker as a pointing device.

When an object is interposed between a touch surface and a finger/touch pen, the change in impedance caused by the object can be measured by the driver software. This phenomenon has been used to develop new interaction techniques. Unlike previous works that focused on the capacitance component in impedance, Ohmic-Touch enhances touch input modality by sensing resistance. Using 3D printers or inkjet printers with conductive materials and off-the-shelf electronic components/sensors, resistance is easily and precisely controllable. We implement mechanisms on touch surfaces based on the electrical resistance of the object: for example, to sense the touching position on an interposed object, to identify each object, and to sense light, force, or temperature by using resistors and sensors. Additionally, we conduct experimental studies that demonstrate that our technology has a recognition accuracy of the resistance value of 97%.

Drawing characters or images using smartphones and tablets is much easier than drawing using trackpads commonly equipped in laptops and desktop computers. The reason is that tablets are absolute coordinate input devices, whereas trackpads are relative coordinates input devices similar to conventional mouse. However, most of the modern laptops have trackpads approximately the same size as a smartphone screen, and they have enough space for hand-writing. We believe that modern trackpads would allow users to write easily as smartphones or tablets, if they properly provide an absolute coordinates input mode. This paper proposes a novel input technique that aims to switch between relative and absolute coordinates input methods seamlessly based on the "carbon copy" metaphor. We display a small workspace ("carbon copy area") on a computer screen that corresponds one-to-one with the handy trackpad. The user can input hand-written characters or images using absolute coordinates input on this virtual carbon copy paper and move it anywhere using relative coordinates. Our technique allows a user to call both absolute and relative coordinates input methods and use them appropriately with arbitrary timing. We developed a prototype application software to utilize this technique based on a preliminary experiment.