Ultra-thin, transparent and flexible tactile sensors based on graphene films with excellent anti-interference

Flexible tactile sensors have been utilized for epidermal pressure sensing, motion detecting, and healthcare monitoring in robotic and biomedical applications. This paper develops a novel piezoresistive flexible tactile sensor based on porous graphene sponges. The structural design, working principle, and fabrication method of the tactile sensor are presented. The developed tactile sensor has 3 × 3 sensing units and has a spatial resolution of 3.5 mm. Then, experimental setup and characterization of this tactile sensor are conducted. Results indicated that the developed flexible tactile sensor has good linearity and features two sensitivities of 2.08 V/N and 0.68 V/N. The high sensitivity can be used for tiny force detection. Human body wearing experiments demonstrated that this sensor can be used for distributed force sensing when the hand stretches and clenches. Thus the developed tactile sensor may have great potential in the applications of intelligent robotics and healthcare monitoring.

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Ultra-Sensitive Flexible Tactile Sensor Based on Graphene Film

Micromachines ◽

10.3390/mi10110730 ◽

2019 ◽

Vol 10 (11) ◽

pp. 730 ◽

Cited By ~ 1

Author(s):

Xiaozhou Lü ◽

Liang Qi ◽

Hanlun Hu ◽

Xiaoping Li ◽

Guanghui Bai ◽

...

Keyword(s):

Industrial Robot ◽

Graphene Film ◽

High Sensitivity ◽

Tactile Sensor ◽

Measurement Range ◽

Tactile Sensors ◽

Piezoresistive Effect ◽

Large Measurement ◽

Pet Film ◽

Maximum Measurement

Flexible tactile sensor can be integrated into artificial skin and applied in industrial robot and biomedical engineering. However, the presented tactile sensors still have challenge in increasing sensitivity to expand the sensor’s application. Aiming at this problem, this paper presents an ultra-sensitive flexible tactile sensor. The sensor is based on piezoresistive effect of graphene film and is composed of upper substrate (PDMS bump with a size of 5 mm × 7 mm and a thickness of 1 mm), medial Graphene/PET film (Graphene/PET film with a size of 5 mm × 7 mm, PET with a hardness of 2H) and lower substrate (PI with fabricated electrodes). We presented the structure and reduced the principle of the sensor. We also fabricated several sample devices of the sensor and carried out experiment to test the performance. The results show that the sensor performed an ultra high sensitivity of 10.80/kPa at the range of 0–4 kPa and have a large measurement range up to 600 kPa. The sensor has 4 orders of magnitude between minimum resolution and maximum measurement range which have great advantage compared with state of the art. The sensor is expected to have great application prospect in robot and biomedical.

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Facile Fabrication of 3D Porous Sponges Coated with Synergistic Carbon Black/Multiwalled Carbon Nanotubes for Tactile Sensing Applications

Nanomaterials ◽

10.3390/nano10101941 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1941 ◽

Cited By ~ 1

Author(s):

Yousef Al-Handarish ◽

Olatunji Mumini Omisore ◽

Wenke Duan ◽

Jing Chen ◽

Luo Zebang ◽

...

Keyword(s):

Carbon Black ◽

High Sensitivity ◽

Tactile Sensor ◽

Fast Response ◽

Wearable Electronics ◽

Tactile Sensors ◽

Multiwalled Carbon ◽

Human Machine Interaction ◽

External Compression ◽

Sensing Applications

Recently, flexible tactile sensors based on three-dimensional (3D) porous conductive composites, endowed with high sensitivity, a wide sensing range, fast response, and the capability to detect low pressures, have aroused considerable attention. These sensors have been employed in different practical domain areas such as artificial skin, healthcare systems, and human–machine interaction. In this study, a facile, cost-efficient method is proposed for fabricating a highly sensitive piezoresistive tactile sensor based on a 3D porous dielectric layer. The proposed sensor is designed with a simple dip-coating homogeneous synergetic conductive network of carbon black (CB) and multi-walled carbon nanotube (MWCNTs) composite on polydimethysiloxane (PDMS) sponge skeletons. The unique combination of a 3D porous structure, with hybrid conductive networks of CB/MWCNTs displayed a superior elasticity, with outstanding electrical characterization under external compression. The piezoresistive tactile sensor exhibited a high sensitivity of (15 kPa−1), with a rapid response time (100 ms), the capability of detecting both large and small compressive strains, as well as excellent mechanical deformability and stability over 1000 cycles. Benefiting from a long-term stability, fast response, and low-detection limit, the piezoresistive sensor was successfully utilized in monitoring human physiological signals, including finger heart rate, pulses, knee bending, respiration, and finger grabbing motions during the process of picking up an object. Furthermore, a comprehensive performance of the sensor was carried out, and the sensor’s design fulfilled vital evaluation metrics, such as low-cost and simplicity in the fabrication process. Thus, 3D porous-based piezoresistive tactile sensors could rapidly promote the development of high-performance flexible sensors, and make them very attractive for an enormous range of potential applications in healthcare devices, wearable electronics, and intelligent robotic systems.

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A Sensitive Piezoresistive Tactile Sensor Combining Two Microstructures

Nanomaterials ◽

10.3390/nano9050779 ◽

2019 ◽

Vol 9 (5) ◽

pp. 779 ◽

Cited By ~ 1

Author(s):

Xuguang Sun ◽

Jianhai Sun ◽

Shuaikang Zheng ◽

Chunkai Wang ◽

Wenshuo Tan ◽

...

Keyword(s):

Low Cost ◽

Body Movement ◽

High Sensitivity ◽

Tactile Sensor ◽

Tactile Sensors ◽

Electronic Skin ◽

Highly Sensitive ◽

Monitoring Applications ◽

Monitoring Application ◽

Fast Dynamic

A tactile sensor is an indispensable component for electronic skin, mimicking the sensing function of organism skin. Various sensing materials and microstructures have been adopted in the fabrication of tactile sensors. Herein, we propose a highly sensitive flexible tactile sensor composed of nanocomposites with pyramid and irregularly rough microstructures and implement a comparison of piezoresistive properties of nanocomposites with varying weight proportions of multi-wall nanotubes and carbon black particles. In addition to the simple and low-cost fabrication method, the tactile sensor can reach high sensitivity of 3.2 kPa−1 in the range of <1 kPa and fast dynamic response of 217 ms (loading) and 81 ms (recovery) at 40 kPa pressure. Moreover, body movement monitoring applications have been carried out utilizing the flexible tactile sensor. A sound monitoring application further indicates the potential for applications in electronic skin, human–computer interaction, and physiological detection.

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Extra-Soft Tactile Sensor for Sensitive Force/Displacement Measurement with High Linearity Based on a Uniform Strength Beam

Materials ◽

10.3390/ma14071743 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1743

Author(s):

Na Ni ◽

Xiaomin Xue ◽

Dongbo Li

Keyword(s):

High Sensitivity ◽

Tactile Sensor ◽

Normal Displacement ◽

Test Results ◽

Tactile Sensors ◽

High Linearity ◽

Uniform Strength ◽

Soft Objects ◽

Force Displacement ◽

Sensing Characteristics

The soft sensing system has drawn huge enthusiasm for the application of soft robots and healthcare recently. Most of them possess thin-film structures that are beneficial to monitoring strain and pressure, but are unfavorable for measuring normal displacement with high linearity. Here we propose soft tactile sensors based on uniform-strength cantilever beams that can be utilized to measure the normal displacement and force of soft objects simultaneously. First, the theoretical model of the sensors is constructed, on the basis of which, the sensors are fabricated for testing their sensing characteristics. Next, the test results validate the constructed model, and demonstrate that the sensors can measure the force as well as the displacement. Besides, the self-fabricated sensor can have such prominent superiorities as follows—it is ultra-soft, and its equivalent stiffness is only 0.31 N·m−1 (approximately 0.4% of fat); it has prominent sensing performance with excellent linearity (R2 = 0.999), high sensitivity of 0.533 pF·mm−1 and 1.66 pF·mN−1 for measuring displacement and force; its detection limit is as low as 70 μm and 20 μN that is only one-tenth of the touch of a female fingertip. The presented sensor highlights a new idea for measuring the force and displacement of the soft objects with broad application prospects in mechanical and medical fields.

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Design of a Sensitive Balloon Sensor for Safe Human–Robot Interaction

Sensors ◽

10.3390/s21062163 ◽

2021 ◽

Vol 21 (6) ◽

pp. 2163

Author(s):

Dongjin Kim ◽

Seungyong Han ◽

Taewi Kim ◽

Changhwan Kim ◽

Doohoe Lee ◽

...

Keyword(s):

High Performance ◽

Strain Sensor ◽

High Sensitivity ◽

Human Robot Interaction ◽

Large Area ◽

Tactile Sensors ◽

Robot Interaction ◽

Mechanical Crack ◽

Flexible Strain Sensor ◽

Contact Sensing

As the safety of a human body is the main priority while interacting with robots, the field of tactile sensors has expanded for acquiring tactile information and ensuring safe human–robot interaction (HRI). Existing lightweight and thin tactile sensors exhibit high performance in detecting their surroundings. However, unexpected collisions caused by malfunctions or sudden external collisions can still cause injuries to rigid robots with thin tactile sensors. In this study, we present a sensitive balloon sensor for contact sensing and alleviating physical collisions over a large area of rigid robots. The balloon sensor is a pressure sensor composed of an inflatable body of low-density polyethylene (LDPE), and a highly sensitive and flexible strain sensor laminated onto it. The mechanical crack-based strain sensor with high sensitivity enables the detection of extremely small changes in the strain of the balloon. Adjusting the geometric parameters of the balloon allows for a large and easily customizable sensing area. The weight of the balloon sensor was approximately 2 g. The sensor is employed with a servo motor and detects a finger or a sheet of rolled paper gently touching it, without being damaged.

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A Vibrissa-Inspired Highly Flexible Tactile Sensor: Scanning 3D Object Surfaces Providing Tactile Images

Sensors ◽

10.3390/s21051572 ◽

2021 ◽

Vol 21 (5) ◽

pp. 1572

Author(s):

Lukas Merker ◽

Joachim Steigenberger ◽

Rafael Marangoni ◽

Carsten Behn

Keyword(s):

Steel Wire ◽

Sense Organ ◽

Tactile Sensor ◽

Tactile Sensors ◽

Measuring Device ◽

3D Object ◽

Torque Transducer ◽

Sense Of Touch ◽

Important Basis ◽

Support Reactions

Just as the sense of touch complements vision in various species, several robots could benefit from advanced tactile sensors, in particular when operating under poor visibility. A prominent tactile sense organ, frequently serving as a natural paragon for developing tactile sensors, is the vibrissae of, e.g., rats. Within this study, we present a vibrissa-inspired sensor concept for 3D object scanning and reconstruction to be exemplarily used in mobile robots. The setup consists of a highly flexible rod attached to a 3D force-torque transducer (measuring device). The scanning process is realized by translationally shifting the base of the rod relative to the object. Consequently, the rod sweeps over the object’s surface, undergoing large bending deflections. Then, the support reactions at the base of the rod are evaluated for contact localization. Presenting a method of theoretically generating these support reactions, we provide an important basis for future parameter studies. During scanning, lateral slip of the rod is not actively prevented, in contrast to literature. In this way, we demonstrate the suitability of the sensor for passively dragging it on a mobile robot. Experimental scanning sweeps using an artificial vibrissa (steel wire) of length 50 mm and a glass sphere as a test object with a diameter of 60 mm verify the theoretical results and serve as a proof of concept.

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Soft magnetic skin for super-resolution tactile sensing with force self-decoupling

Science Robotics ◽

10.1126/scirobotics.abc8801 ◽

2021 ◽

Vol 6 (51) ◽

pp. eabc8801

Author(s):

Youcan Yan ◽

Zhe Hu ◽

Zhengbao Yang ◽

Wenzhen Yuan ◽

Chaoyang Song ◽

...

Keyword(s):

External Disturbance ◽

Super Resolution ◽

Tactile Sensor ◽

Human Robot Interaction ◽

Tactile Sensors ◽

Dexterous Manipulation ◽

Robot Interaction ◽

Flexible Film ◽

Challenging Tasks ◽

External Forces

Human skin can sense subtle changes of both normal and shear forces (i.e., self-decoupled) and perceive stimuli with finer resolution than the average spacing between mechanoreceptors (i.e., super-resolved). By contrast, existing tactile sensors for robotic applications are inferior, lacking accurate force decoupling and proper spatial resolution at the same time. Here, we present a soft tactile sensor with self-decoupling and super-resolution abilities by designing a sinusoidally magnetized flexible film (with the thickness ~0.5 millimeters), whose deformation can be detected by a Hall sensor according to the change of magnetic flux densities under external forces. The sensor can accurately measure the normal force and the shear force (demonstrated in one dimension) with a single unit and achieve a 60-fold super-resolved accuracy enhanced by deep learning. By mounting our sensor at the fingertip of a robotic gripper, we show that robots can accomplish challenging tasks such as stably grasping fragile objects under external disturbance and threading a needle via teleoperation. This research provides new insight into tactile sensor design and could be beneficial to various applications in robotics field, such as adaptive grasping, dexterous manipulation, and human-robot interaction.

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A high-sensitivity 3-D tactile sensor for minimally invasive surgery

2007 IEEE Sensors ◽

10.1109/icsens.2007.4388523 ◽

2007 ◽

Cited By ~ 2

Author(s):

Rakesh B. Katragadda ◽

Zhuo Wang ◽

Yong Xu

Keyword(s):

Minimally Invasive Surgery ◽

Minimally Invasive ◽

Invasive Surgery ◽

High Sensitivity ◽

Tactile Sensor

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Fabrication of Piezoelectric Polyvinylidene Fluoride (PVDF) Polymer-Based Tactile Sensor Using Electrospinning Method

Nano Hybrids and Composites ◽

10.4028/www.scientific.net/nhc.12.42 ◽

2016 ◽

Vol 12 ◽

pp. 42-50 ◽

Cited By ~ 1

Author(s):

N. Manikandan ◽

S. Muruganand ◽

K. Sriram ◽

P. Balakrishnan ◽

A. Suresh Kumar

Keyword(s):

Polyvinylidene Fluoride ◽

Biomedical Application ◽

Electric Pulse ◽

High Sensitivity ◽

Tactile Sensor ◽

Main Role ◽

Nano Structure ◽

Sem Image ◽

Β Phase ◽

Α Phase

The polyvinylidene fluoride (PVDF) nanofiber has widely investigated as a sensor and transducer material, because of its high piezo and Ferro electric properties. The novel nano structure of PVDF has attracted considerable interest in the bio sensing and biomedical application. This paper deals with PVDF Tactile sensor. Basically The PVDF acts as piezoelectric effect which convert load into electrical signals. The tactile sensor has a main role for visual handicap and robotics. Any physical activities of robotic in all industrial the tactile sensor is a crucible role, whether it can left the object or handling glass parts pressure of object is main. The Sandwich type PVDF base tactile sensor has been fabricated using nanofiber. Using electro spinning method, the PVDF based nanofiber coated over coper the electrodes. In normal, the PVDF has α-phase and while applying electric pulse the PVDF polymer would be changed from α-phase into β-phase. Only in β-phase, the PVDF act as piezo electrics sensor and measure the piezoelectricity simultaneously measure pressure and temperature in real time. The pressure was monitored from the change in the electrical resistance via the piezo resistance of the material. The enhancement of PVDF properties has been carried by using SEM. The SEM image result showed that the size of nanofiber, the size of nanofiber is varied in the range of (180 nm-400 nm) with smooth surface. The X-Ray diffraction has shown that the PVDF was aggregated with the β-phase crystalline nature. Due to β-phase it was act as a piezo electric prosperity’s and its results are very high sensitivity.

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