Multi-Touch Interaction Generation Device by Spatiotemporally Switching Electrodes

With the spread of devices equipped with touch panels, such as smartphones, tablets, and laptops, the opportunity for users to perform touch interaction has increased. In this paper, we constructed a device that generates multi-touch interactions to realize high-speed, continuous, or hands-free touch input on a touch panel. The proposed device consists of an electrode sheet printed with multiple electrodes using conductive ink and a voltage control board, and generates eight multi-touch interactions: tap, double-tap, long-press, press-and-tap, swipe, pinch-in, pinch-out, and rotation, by changing the capacitance of the touch panel in time and space. In preliminary experiments, we investigated the appropriate electrode size and spacing for generating multi-touch interactions, and then implemented the device. From the evaluation experiments, it was confirmed that the proposed device can generate multi-touch interactions with high accuracy. As a result, tap, press-and-tap, swipe, pinch-in, pinch-out, and rotation can be generated with a success rate of 100%. It was confirmed that all the multi-touch interactions evaluated by the proposed device could be generated with high accuracy and acceptable speed.

Equivalent Electrical Circuit Modeling of CNT-Based Transparent Electrodes

Among the various applications of carbon nanotubes (CNTs) that have been investigated since the discovery of their exceptional potential in the electronic field, great interest has been directed towards the creation of carbon-based materials capable of replacing Indium Tin Oxide (ITO) as a transparent electrode. Such transparent conductive films find application in touch panels, LCD screens, OLED displays, photovoltaic cells, and many others. This review presents a collection of techniques that have been proposed during the last decade for the modeling of carbon nanotube-based materials by means of equivalent electrical networks. These networks represent the electrical properties of CNT-based conductive thin films in a way that can be easily included in circuit simulators for the simulation-assisted design of the different devices under static and dynamic conditions.

Highly stretchable metal-polymer hybrid conductors for wearable and self-cleaning sensors

We fabricated semitransparent and stretchable hybrid Ag-polytetrafluoroethylene (PTFE) conductors on a polyurethane (PU) substrate for use in high-performance wearable and self-cleaning sensors. The highly conductive Ag metal and stretchable PTFE polymer matrix were cosputtered, embedding the self-formed Ag in the PTFE matrix. Depending on the cosputtering RF and DC power ratio, the Ag-PTFE conductors showed a sheet resistance of 3.09–17.23 Ω/square and an optical transparency of 25.27–38.49% at a wavelength of 550 nm. Under the optimal cosputtering conditions, the Ag-PTFE electrode showed outstanding stretchability (strain 20%) and reversible hysteresis, enabling the production of stretchable and semitransparent conductors. In addition, the very small critical inward/outward bending radius near 1 mm and the hydrophobic surface indicate that the Ag-PTFE films could also be applied in wearable and self-cleaning devices. The suitability of the high stretchability and low sheet resistance of the sputtered Ag-PTFE conductor was verified by using it as a stretchable interconnector for commercial ELs, LEDs, and strain sensors. We applied the Ag-PTFE film as a semitransparent conductor for stretchable touch panels and electromyography sensors. Cosputtered Ag-PTFE films are promising stretchable conductors for a variety of applications in next-generation wearable devices.

Skin-inspired self-healing semiconductive touch panel based on novel transparent stretchable hydrogels

As the increasing importance of human-machine interactions, stretchability, biocompatibility and self-healing behavior will play a more significant role in the next-generation touch panels so as to allow integration with a...

A Force–Voltage Responsivity Stabilization Method for Piezoelectric Touch Panels in the Internet of Things

Piezoelectric force touch panels are extensively utilized as human-machine interfaces for 3-dimensional touch sensing in internet of things (IoT) applications. However, the unstable force voltage responsivity issue induced by different touch orientations limits the successful use of piezoelectric touch panels. In this article, a piezoelectric touch panel, which is sensitive to both capacitive and force stimulation, is assembled; and a touch orientation classification technique is developed to calibrate the detected force amplitude by training a machine learning model with finger induced capacitive information. Finally, a high stable force voltage responsivity of 87.5% is achieved experimentally.

A Force–Voltage Responsivity Stabilization Method for Piezoelectric Touch Panels in the Internet of Things

Piezoelectric force touch panels are extensively utilized as human-machine interfaces for 3-dimensional touch sensing in internet of things (IoT) applications. However, the unstable force voltage responsivity issue induced by different touch orientations limits the successful use of piezoelectric touch panels. In this article, a piezoelectric touch panel, which is sensitive to both capacitive and force stimulation, is assembled; and a touch orientation classification technique is developed to calibrate the detected force amplitude by training a machine learning model with finger induced capacitive information. Finally, a high stable force voltage responsivity of 87.5% is achieved experimentally.