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Technology Review - 3D touch
Huawei’s force touch vs. Apple’s 3D touch
In September 2015, Huawei, the Chinese smartphone maker, unveiled the world’s first smartphone loaded with force touch. One week later, Apple launched iPhone 6S, for which it presented 3D touch as technological forte. 3D touch is pressure sensitive technology and executes specific functions by responding to different levels of pressure. The new interface, which consists in pressure detection in touch sensor, is now drawing spotlight, touted as the next generation of multitouch.
Fig. 1 ― Huawei’s Mate S (left) loaded with pressure tensor and Apple’s iPhone 6S (right); source: Yonhap News / Macworld
The arrival of advanced smart sensors
As advanced smart sensors become smaller and cheaper, their integration accelerates and the usability of their functions increases. And it requires some other method that surpasses the existing touch sensor technology. Especially, mobile devices want to realize greater precision in their operation all the while performing various interfaces with just one finger. For example, the emerging buzzwords are touch sensor or touch screen technology, which applies the technology that even considers sensibility by detecting not just positions but also the degree of pressure.
Such pressure sensors are usable and partially applied in not only smart mobile devices like smartphone and tablet, but also various wearable IoT devices such as user body position measurement, gesture sensing, and healthcare, while the scope of application is gradually expanding. Next-generation pressure sensor technology constitutes the core of 3D touch which Apple recently adopted after multitouch. And anyone who wants to pre-empt the core source technology that can innovate the mobile and wearable device industry needs to develop the core technology of pressure sensor. Due to the limitations involved in the material and technology for electrodes used in touch screen, the industry is calling for new technology that uses new materials.
Limitations of existing electrode materials and display technology
Korea leads smartphone and display, with Korea-based Samsung Electronics and LG Electronics demonstrating worldwide competitive advantage in smartphone and tablet PC. Used in transparent electrodes adopted for various electronic devices, ITO has seen explosive demand as it is used in touch screen technology. For indium, the key material for ITO, however, the industry is increasingly dependent on China, and with the depletion of indium looming as a problem, we face a growing demand for a replacement material. Besides, due to the physical and chemical properties of ITO, there is a limit to its expansion into various applications.
Prospects for the market for graphene-based touch screen
Samsung Techwin R&D Center, Prof. Hong Byeong-hee of Seoul National University, Sungkyunkwan University Advanced Institute of Nanotechnology, and Graphene Square disclosed that they applied a touch screen made with large-area graphene in smartphone Galaxy, as featured in the Dec. 23, 2013 issue of ACS Nano, an international academic journal on nano. Samsung and Apple are striving so fiercely to dominate the display industry that we now have the phrase, ‘graphene screen war’. Currently, Apple has registered minimum two graphene-related patents in the US, whereas Samsung has acquired at least 38 related patents in the US.
If graphene is applied in the currently available pressure sensor touch screen, it may expand into flexible display and wearable devices. Graphene-based pressure sensor is expected to be the core technology for next-generation smartphone’s touch screen panel.
Mechanism for detecting both positions and pressure
Graphene Square has patented technology for graphene-based touch sensor that can detect both positions and pressure through changes in resistance. Multitouch function can be realized by applying in touch sensor the X-axis and Y-axis graphene electrodes patterned on the material. Pressure can be measured with the changes in graphene resistance caused by pressure applied from outside, and positions can be detected with the distribution of changes in resistance that occur in different lines of graphene electrodes. Hence the realization of simultaneous detection of pressure and positions.
Using the size of applied pressure, one can add various functions such as adjusting font thickness, adjusting sound volume, and camera zoom in/out. If electrodes are manufactured with graphene, problems with wrong alignment can be prevented or minimized, while uniformity and reproducibility for products can be easily ensured. Moreover, as graphene registers excellent transparency and mechanical properties, it can be used to make touch sensor with flexibility and stretchability. Therefore, a sensor that applies Graphene Square’s technology can also be used as a flexible 3D sensor.
Applications and Prospects of 3D pressure sensor
Looking ahead, graphene-based pressure sensor has unlimited potential. It can not only take dominant position in the competition for innovation among mobile devices, but will also create entirely new kind of wearable technology and business through developing an interface that maximizes user experience. When built in smart wear, it can measure the angle and speed at which the muscle operates and transmits them to a fitness app for analysis. And when attached to the sole of a shoe, it can measure the weight distribution and weight and transmit them to mobile devices real time. This way, it will also enable the development of games, education software, and apps that adopt 3D input method. Now that Apple has applied force touch to iPhone 6S, the technology is bound to emerge as the kernel of smartphone technology down the road.
Video : https://youtu.be/0ell4jGDHrw