Metamorphic Stretchable Touchpad

Abstract

nanowires (AgNWs) in polydimethylsiloxane (PDMS) [24] or liquid metals [25,26] as stretchable interconnects. However, the performances were limited to low lateral resolution capacitive sensing. The reported methods may, in our view, be challenged when it comes to high resolution patterning and multilayer registration which are two requirements to fabricate higher quality devices.In this article, we report on the design and realization of a 3D metamorphic touchpad which is able to morph reversibly from a planar to a hemispherical form. Moreover, the touchpad can be wrapped around a 3D object or body. To the best of our knowledge such a device has not been made. We mimic a commercially available universal serial bus (USB) connectable touchpad layout and translate the particular design and key elements to become metamorphic. This way the existing USB computer interface and software could be used. The approach replaces the rigid printed circuit board (PCB) with a metamorphic analog referred to as "metamorphic-PCB". Metamorphic PCBs describe a new concept and the realization of such boards to produce the touchpad is presented. Once fully developed, most rigid board based electronic systems known today, can be mimicked and translated to become metamorphic in the future. Figure 1 describes the 3D metamorphic touchpad design approach. The actual design mimics the checker board pattern found in most touchpad designs. The X-ray image shows ( Figure 1A) the layout (SpeedLink SL-6331-BK, Weertzen, Germany) we used as inspiration. The goal was to replace the capacitive touch sensor array with a metamorphic design with a similar behavior to reuse the existing capacitive touch controller, USB connection, and machine interface. The approach replaces the rigid-PCB of the commercial device with a metamorphic analog. The original design uses, as revealed by the X-ray image, two electrically separated metal layers which are patterned to form addressable rows and columns of checkers. Figure 1B schematically illustrates the operation principle of this touchpad which is based on mutual capacitance. Since the physical dimension of the conductive plates is the same, the plates contain an equal amount of charges at normal condition. Placing the finger onto the array will change the charge distributions of the corresponding plates resulting in changes in the mutual capacitance of a particular column and row, leading to a point under single touch operation (pointed by a black circle). These nonstretchable checker plates are replaced using a stretchable meander-shaped metal mesh [27] (Figure 1C). The mesh mimics the checker shape to maintain a similar Conventional touchpads are an example of a common human-machine interface. They are rigid devices with a limited usability without any form of adaptability and conformity to different morphologies necessary for gaming and virtual reality applications. A metamorphic touchpad is an envisioned conceptual approach of shape changing electronics. To demonstrate this, a multipurpose touchpad able to s...

Haptic Perception, Mechanics, and Material Technologies for Virtual Reality

“…Recently, advances in stretchable and soft electronics, and functional materials, are enabling new devices that can stretch and conform to curved, soft, or moving surfaces, such as the human body. [ 92,93 ] Thus, many of the most popular research topics in soft electronics concern the engineering of skin‐interfaced sensors, sometimes also referred to as e‐skin. Such technologies have applications in robotics, and in human‐wearable devices, such as wearable haptic augmented reality systems that capture contact areas, forces, or movements with the fingers and provide visual and haptic feedback in order to perceptually alter or augment objects in a physical environment.…”

Emerging Material Technologies for Haptics

“…However, both types require stretchable substrate. Although most of the reported examples of the stretchable haptic devices are related to sensing and robotic, there are a few examples of stretchable tactile displays based on stretchable actuators. Some of these devices have been discussed earlier and Table 4 presents a short literature review on haptic devices, their mechanisms, and methods used to realize the devices.…”

Integrated multilayer stretchable printed circuit boards paving the way for deformable active matrix

“…A dramatic increase in research activities has been perceived for last decade to enable mechanically stretchable and deformable functional electronic devices 1–4 . Consequently, a large number of stretchable devices have been realized demonstrating a wide range of diverse applications that includes soft robotics 5,6 , actuators 7 , electronic eye cameras 8 , epidermal electronics 9 , wearable electronics 10,11 , metamorphic electronics 12,13 , edible electronics 14 , acoustoelectronics 15,16 , health monitoring devices 17–19 , smart textiles 20 to give a few examples. Most of these demonstrators often use highly specialized technologies and unconventional materials that make these technologies more interesting for research, but less favorable for industrial production for mass people.…”

“…The reported method enabled high temperature processing, high alignment and registration, and allowed conventional chip assembly methods on a rigid carrier. However, the previously demonstrated methods used only a single active layer without complex routing of the metal tracks, which limited the complexity of the circuit and the device 12,13,30 . In this article, we engineered a similar method to realize integrated multilayer SPCB and demonstrate an alternative development towards the realization of stretchable electronics with higher integration density capabilities by introducing stable VIAs through interconnection between different metallization layers.…”