Design and fabrication of a flexible three-axial tactile sensor array based on polyimide micromachining

This paper describes the design and fabrication of a flexible three-axial tactile sensor array using advanced polyimide micromachining technologies. The tactile sensor array is comprised of sixteen micro force sensors and it measures 13 mm × 18 mm. Each micro force sensor has a square membrane and four strain gauges, and its force capacity is 0.6 N in the three-axial directions. The optimal positions of the strain gauges are determined by the strain distribution obtained form finite element analysis (FEA). The normal and shear forces are detected by combining responses from four thin-film metal strain gauges embedded in a polyimide membrane. In order to acquire force signals from individual micro force sensors, we fabricated a PCB based on a multiplexer, operational amplifier and microprocessor with CAN network function. The sensor array is tested from the evaluation system with a three-component load cell. The developed sensor array can be applied in robots’ fingertips, as well as to other electronic applications with three-axial force measurement and flexibility keyword requirements.     

Mechanical feedback analysis of a ferrofluid-based module with 2D dynamic traveling waves for tactile display application

With the advances of human-machine systems, tactile displays have become one of the important features for modern products. Tactile feedback can increase working efficiency and help humans to explore new environments or objects by the sense of touch. This study used a 3 × 3 electromagnet array and a ferrofluid bladder to build a tactile display module, which can create smooth and continuous real-time 2-D dynamic traveling waves. The interactions of magnetic fields between electromagnets in the array were used to control the directions of the magnetic lines of force to create different graph patterns. Our user test showed that the overall tactile perception rate was 74% for the 2-D dynamic graph patterns generated using the ferrofluid-based tactile display module.     

Bezel free design of organic light emitting diode display via a‐InGaZnO gate driver circuit integration within active array

In this article, we described an innovative design technology of active matrix organic light emitting diode (AMOLED) display, to provide a bezel free design. We designed gate driver circuit of amorphous indium‐gallium‐zinc oxide thin‐film transistors (TFTs) not on the bezel area but within the active array. Although we applied challengeable design, no degradation of electrical/optical properties of panel was observed. Because we effectively prevented capacitive coupling and interference between the emission circuit and integrated gate driver circuit in active array, finally, we successfully demonstrated a bezel free designed AMOLED display of 18.3″ HD (1366 × 768) driven by a‐InGaZnO TFTs.     

Development of a bioinspired MEMS based capacitive tactile sensor for a robotic finger

This paper presents the development of a MEMS based capacitive tactile sensor intended to be incorporated into a tactile array as the core element of a biomimetic fingerpad. The use of standard microfabrication technologies in realising the device allowed a cost efficient fabrication involving only a few process steps. A low noise readout electronics system was developed for measuring the sensor response. The performance of both bare and packaged sensors was evaluated by direct probing of individual capacitive sensor units and characterising their response to load–unload indentation cycles.     

Tactile display and vibrotactile pattern recognition on the torso

A wirelessly controlled tactile display has been designed, fabricated and tested for use as a navigation aid. The display comprises a 4 × 4 array of vibrating motors that is mounted on a waist band and stimulates the skin across the lower back. Three types of electromechanical actuators were evaluated for use in the display; based on their mechanical performance and power requirements, two of these motors were then used to fabricate tactile displays. The performance of the displays and the wireless tactile control units was assessed experimentally by having subjects identify which of eight possible vibrotactile patterns was presented to the lower back. The results indicated that subjects could recognize the vibrotactile patterns with almost perfect accuracy and that there was no difference between the two types of motor used for the displays. Moreover, the ability to recognize the pattern of vibrotactile stimulation was superior on the back as compared to the forearm. A further experiment confirmed that the tactile display can be used as a navigation aid outdoors and that the vibrotactile patterns presented can be interpreted as directional or instructional cues with almost perfect accuracy.     

A meta-surface loaded,low profile 28 GHz phased array antenna

A low-profile wide-scan phased array for 28 GHz 5G band operation, based on the current sheet array (CSA) concept, is presented in this work. The array is dual-polarized with horizontally and vertically polarized dipoles are placed in close proximity to leverage intentional capacitive coupling. A meta-surface based on fully split rings is printed on the top of the matching layer, contributing to wide-scan performance. A capacitive metallic plate is placed below the cross-section formed between orthogonal dipole elements to subdue the in-band coupled-loop modes. The design is demonstrated to operate at 26–30 GHz with voltage standing wave ratio (VSWR) <3 for ±60° scanning in principal planes, with a low-profile 0.26λ_h. The simulations are validated by measuring an 8 × 8 array prototype, which shows good agreement with the simulated predictions.     

振动触觉纹理再现技术研究综述

纹理力触觉再现是通过特定的硬件装置模拟产生与物体纹理表面接触时的触感，使用户能感受到物体的粗糙度、软硬度等纹理特征信息。振动刺激作为再现物体触觉信息的一种刺激方式，在纹理触觉再现中被广泛运用，产生了不同的振动触觉表达装置和纹理触觉表达方法。从纹理触觉认知的角度，阐述了人对振动刺激的触觉感知生理学基础；介绍了纹理触觉再现的原理和方法；从振动与纹理特征的映射方法以及振动刺激方式两个方面分析了目前振动触觉纹理再现技术的发展现状；最后对相关研究的发展进行了总结展望。     

High‐resolution and compact virtual mouse using lens arrays to capture finger images on light sensors

To realize a finger positioning device, as called “virtual mouse,” to replace a touchpad, touchscreen, or even real mouse, current positioning technologies cannot achieve a sufficient resolution, a compact volume, and a simple detection algorithm simultaneously. For this problem, using a light‐emitting diode source, two lens arrays, and two light sensors, we design and implement a virtual mouse prototype. The optical architecture is carefully determined for a compact volume, a sufficient resolution, and a high detection accuracy. Corresponding to a compact system volume of 3.1 mm (thickness) × 4.5 mm (length) × 2, a theoretical resolution higher than 25 pixels per inch (ppi) can be obtained over a working area of 10 cm × 10 cm. Experiments are also implemented, in which a mean detection error of 0.24 cm that corresponds to approximately two distinguishable points, and a minimal resolution of 26 ppi over the whole working area are verified. If the system thickness is relaxed to 25 mm, a resolution higher than 200 ppi can be achieved. The proposed virtual mouse, which is simple enough and potential to be extended for three‐dimensional position detection, can be integrated with a flat panel display to achieve a compact display application that can interact with users.     

Foot pressure monitoring using single layer carbon loaded piezoresistive material

Arthritis is an intense or unremitting irritation ailment that influences the joints, connective tissues, muscle, ligaments, and stringy tissue. It is the leading cause of inability among individuals more than 50 years old in a developed country. Also, it tends to strike amid the most beneficial long periods of adulthood, regularly causing torment and deformation. It offers to ascend to tremendous healthcare expenditures and loss of work. With the existing system, there is a different size of FSR sensors used for foot pressure analysis. A sole with significant pressure points (2–9) was designed to analyze the foot pressure, but unfortunately, the foot size differs from one person to another person. So the single sole design setup cannot be used for all the persons. In the proposed method, a sensor array designed with single-layer carbon loaded polyethylene film was designed, and each sensor with sides 21 mm × 21 mm to form the 7 × 3 array pattern of the foot pressure pad. By using the array foot pressure pad, we can analyze the pressure points throughout the pad. Each of the sensors in the array is having a gap of 5 mm. The output analog signal acquired, and these electrical signals may result in preemptive of the knee problem.     

Fabrication of wireless sensors on flexible film using screen printing and via filling

Wireless sensors are fabricated on flexible plastic films by means of screen printing and via-hole filling. The wireless sensors are battery free with data and power transmission functions. The sensors, fabricated on polyethylene terephtalate films, are designed based on RFID technology. Using an additive patterning process known as screen printing, metallization on polymer films is created. Both sides of a polymer film are printed with metallic patterns and connected with micro vias filled with conductive paste. One side of the film consists of printed electrical traces for discrete components like resistors and transistors that would be mounted onto it; the other side consists of a printed inductive coil used for wireless data and power transmission. The micro vias, which have a diameter of 120 μm, are formed by mechanical punching and filled with conductive silver paste. The size of one sensor unit is approximately 2 cm × 1.5 cm; an array of 4 × 7 sensor units are printed over an area of 15 cm × 15 cm on a PET film. Details of manufacturing processes, component assembly and functionality test are presented in this paper.     

Vibration perception and excitatory direction for haptic devices

Vibration feedback is one of the most popular ways to communicate between human and haptic interfaces nowadays. In order to deliver a wider variety of information accurately and efficiently, significant design factors of the vibration need to be investigated and applied to haptic devices. In this study, the excitatory direction was examined as a design factor of the vibration in terms of sensitivity and emotion. We conducted two experiments. In the first experiment, the sensitivities of three excitatory directions—X (lateral), Y (fore-and-aft) and Z (vertical) axes were estimated by the absolute thresholds of the vibration perception with two frequency levels (150 and 280 Hz). Based on ten participants’ estimated absolute thresholds, we conclude that the vibration with X axis is less sensitive than Z axis at the frequency of 150 Hz, while the vibration with Y axis is less sensitive than Z axis at the frequency of 280 Hz. In the second experiment, the agreeability of 29 emotional expressions to the vibrations was measured by a 7-point scale with a total of 12 conditions (2 frequencies × 2 amplitudes (i.e., 50 × 10⁻³ and 500 × 10⁻³ g) × 3 excitatory directions). Based on 20 participants’ responses, it is concluded that at the frequency of 150 Hz and the amplitude of 50 × 10⁻³ g, the vibration is perceived as ‘light’, and as even ‘lighter’ if the vibration is with Y axis rather than with Z axis. Likewise, at the frequency of 150 Hz and the amplitude of 500 × 10⁻³ g, the vibration is perceived as ‘repulsive’, and as even ‘more repulsive’ if the vibration is with Y or Z axis rather than with X axis. Therefore, three excitatory directions can be selectively utilized to design the distinguishable vibration by its sensitivity and emotion.     

A compact planar distributed tactile display and effects of frequency on texture judgment

This paper describes the development of a planar distributed tactile display and the evaluation of the results of its effectiveness for displaying textures. The tactile display is composed of a 6 × 5 pin array actuated by 30 piezoelectric bimorphs. The distance between each pin's centers is 1.8 mm. Vertical excursion of each pin is controlled over a 0–0.7 mm range. Perceptual experiments were conducted to evaluate the performance of the system under three conditions: active touch, passive touch with vibration and passive touch without vibration. The experimental results showed that vibrational stimuli helped subjects discriminate tactile patterns. Measurements of the error rate during discrimination tasks were used to find an optimal vibration frequency for stimuli presented at a constant sensation level (32 SLdB above threshold). The experiment was repeated, this time holding the energy transferred mechanically to the fingertip tissue constant. At low frequencies, we found that the passive stimulation allowed subjects to discriminate just as well as active touch of static stimuli did. The results suggested new possibilities for displaying texture using passive touch, constant energy and spatially varied vibration frequency.     

SmartTouch: electric skin to touch the untouchable

Augmented haptics lets users touch surface information of any modality. SmartTouch uses optical sensors to gather information and electrical stimulation to translate it into tactile display. Augmented reality is an engineer's approach to this dream. In AR, sensors capture artificial information from the world, and existing sensing channels display it. Hence, we virtually acquire the sensor's physical ability as our own. Augmented haptics, the result of applying AR to haptics, would allow a person to touch the untouchable. Our system, SmartTouch, uses a tactile display and a sensor. When the sensor contacts an object, an electrical stimulation translates the acquired information into a tactile sensation, such as a vibration or pressure, through the tactile display. Thus, an individual not only makes physical contact with an object, but also touches the surface information of any modality, even those that are typically untouchable.     

A Multi-Modal Haptic Interface for Virtual Reality and Robotics

In this paper we present an innovative haptic device that combines the electro-tactile stimulation with the force and visual feedbacks in order to improve the perception of a virtual world. We discuss the sensation evoked in a user by the haptic, force, and the visual interface as provided by this device, implemented as a special glove, equipped with sensors and actuators connected to a PC. The techniques used to recreate tactile and kinesthetic sensations are based on an innovative use of cutaneous stimulation integrated with actuators and 3D modelling techniques. We discuss about the specificity of haptic interfaces, their controllers, their open problems. We present results about generating the sensation of touching virtual objects with our device. Experiments show also that, using a multi-modal sensorial pattern of stimulation, the subject perceives more realistically the virtual object. We discuss the possible use of the same technique as a way to interface intelligent robots.     

Tactile array sensor for object identification using complex moments

This article explores object identification by complex moment features obtained using a tactile array sensor. Some complex moment invariants have been derived and implemented eliminating the effects of lateral displacement and rotation from the tactile images. The generation of a decision tree and use of the complex moment features, allow easy identification of object shapes from the tactile array sensor.     

Synergistic visual/haptic rendering modes for scientific visualization

Our approach uses a visual/haptic interface to display scientific data both graphically and haptically. The haptic interface provides a natural means of interacting with the data through direct tactile sensing and manipulation of the data display. Our experience with this interface suggests that users understand the data more clearly when the haptic component acts as a synergistic companion to the visual display. That is, rather than replace the visual display of data or display disparate data haptically, the haptic component reinforces and clarifies visual information via compatible haptic data rendering.     

小型化柔性触觉再现装置

提出了一种小型化的具有实时触觉反馈作用的人机接口装置的设计方法,以控制弹性梁的有效变形长度为核心,保证了触觉再现的实时性和准确性,从而可以在操作者指端大范围再现虚拟对象或远程对象的刚度。介绍了该小型化人机触觉再现接口装置的硬件设计和软件设计。该实时触觉再现接口具有尺寸小、刚度再现范围大,可方便与鼠标相结合等特点,可广泛应用于遥操作机器人和虚拟现实领域。     

Integrated SWCNT sensors in micro-wind tunnel for air-flow shear-stress measurement

We have developed SWCNT sensors for air-flow shear-stress measurement inside a polymethylmethacrylate (PMMA) “micro-wind tunnel” chip. An array of sensors is fabricated by using dielectrophoretic (DEP) technique to manipulate bundled single-walled carbon nanotubes (SWCNTs) across the gold microelectrodes on a PMMA substrate. The sensors are then integrated in a PMMA micro-wind tunnel, which is fabricated by SU-8 molding/hot-embossing technique. Since the sensors detect air flow by thermal transfer principle, we have first examined the I–V characteristics of the sensors and confirmed that self-heating effect occurs when the input voltage is above ~1 V. We then performed the flow sensing experiment on the sensors using constant temperature (CT) configuration with input power of ~230 μW. The voltage output of the sensors increases with the increasing flow rate in the micro-wind tunnel and the detectable volumetric flow is in the order of 1 × 10⁻⁵m³/s. We also found that the activation power of the sensors has a linear relation with 1/3 exponential power of the shear stress which is similar to conventional hot-wire and polysilicon types of convection-based shear-stress sensors. Moreover, measurements of sensors with different overheat ratios were compared, and results showed that sensor is more sensitive to the flow with a higher overheat ratio.     

Digitally-controlled array of solid-state microcoolers for use in surgery

This paper presents an approach for generating a well-defined cooling pattern over an area of tissue. An array of solid-state microcoolers is used, which could be included in a probe that provides local cooling. This medical instrument can be used for removal of scar tissue in the eye or for the rapid stopping of bleeding due to micro-cuts, which makes it a useful tool to medical doctors and could make surgery more secure to the patient. The array of microcoolers is composed of 64 independent thermo-electric elements, each controlled using an integrated circuit designed in CMOS. The independent control allows the flexible programming of the surface temperature profile. This type of control is very suitable in case abrupt temperature steps should be avoided. Cooling by lateral heat flow was selected in order to minimize the influence of heat by dissipation from the electronic circuits. Moreover, a thermo-electric component with lateral heat allows fabrication of the cooling elements using planar thin-film technology, lithography and wet etching on top of the silicon wafer. This approach is potentially CMOS compatible, which would allow for the fabrication of the thermo-electric elements on top of a pre-fabricated CMOS wafer as a post-process step. Each pixel is composed of thin-films of n-type bismuth telluride, Bi₂Te₃ and p-type antimony telluride, Sb₂Te₃, which are electrically interconnected as thermocouple. These materials have excellent thermoelectric characteristics, such as thermoelectric figures-of-merit, ZT, at room temperatures of 0.84 and 0.5, respectively, which is equivalent to power-factors, PF, of 3.62 × 10⁻³ W K⁻¹ m⁻² and 2.81 × 10⁻³ W K⁻¹ m⁻², respectively. The theoretical study presented here demonstrates a cooling capability of 15°C at room temperature (300 K ≈ 27°C). This cooling performance is sufficient to maintain a local tissue temperature at 25°C, which makes it suitable for the intended application. A first prototype was successfully fabricated to demonstrate the concept.     

Ubi-Pen: A Haptic Interface with Texture and Vibrotactile Display

The Ubi-Pen is a pen-like haptic interface incorporating a compact tactile display and a vibrating module. It can represent tactile patterns and provide feedback with the click of a button. It's also applicable to combined force- and tactile-feedback display.