Three-axis Tactile Sensor Research Articles

A Solid-Liquid Composite Flexible Bionic Three-Axis Tactile Sensor for Dexterous Hands

A Solid-Liquid Composite Flexible Bionic Three-Axis Tactile Sensor for Dexterous Hands

Effect of prophylactic dressings to reduce pressure injuries: a polymer-based skin model.

This study evaluated the effect of pressure injury (PI) prophylactic dressings used for patients at high risk of PI development to reduce friction, shear force and pressure, and their combined force, in an original polymer-based skin model. A low-friction outer-layer hydrocolloid (LFH) dressing and a multilayered silicone foam (MSF) dressing were used. Before application, compression and friction properties were measured. Our original experimental model-the 'simulated skin-shearing test'-consisted of: a weight; a polyurethane-based skin model containing a three-axis tactile sensor; dressings; a table covered with bedsheets; and a mechanical tester, by which the interface friction force, internal shear force and pressure were measured continuously during skin model movements. An estimated combined force generated by internal shear and pressure was represented as a vector. A model with no dressing was used as a control. The LFH dressing had significantly higher compression strength versus the MSF dressing. In contrast, the dynamic coefficient of friction was lower for the LFH dressing versus the MSF dressing (p<0.05). In simulated skin-shearing test results, shear forces were 0.45N and 0.42N for LFH and MSF dressings, respectively, with no significant difference. The estimated combined force was lower for the MSF dressing compared with that of the LFH dressing and control. The shear force-reducing effect in the skin model was equivalent between the LFH and MSF dressings. However, the MSF dressing significantly reduced the force generated by a combination of internal shear force and pressure compared with the LFH dressing.

High-performance flexible tactile sensor enabled by multi-contact mechanism for normal and shear force measurement

Flexible tactile sensors are essential components of pressure monitoring in the fields of electronic skin, health care, and robotic hands. Currently, there is a great demand for tactile sensors that exhibit high sensitivity, linearity, and a wide dynamic range, as they play an increasingly vital role in information exchange. However, it is still challenging to achieve a synchronous improvement in performance through a simple strategy. Theoretically, we present the multi-contact mechanism for sensing enhancement by changing the contact mode and the initial state. Specifically, the curved polydimethylsiloxane (PDMS)/multi-walled carbon nanotubes (MWCNTs) surface ensures the continuity of contact deformation, leading to a wide dynamic range. Besides, the discrete resistor pillars on the micro-honeycomb electrodes (MHEs) depress the initial current, and thus enhance the sensitivity. Experimentally, we utilize microelectromechanical systems (MEMS) technology to fabricate the MHEs, mainly including patterning and micro-electroforming processes. By adjusting the resistor distribution density and the curvature of PDMS contact, the extraordinary sensitivity is tuned from 25.88 kPa−1 to 64.68 kPa−1, and the maximum detection pressure switches between 500 kPa and 1400 kPa, which is consistent with the physical model. Furthermore, a proof-of-concept of the flexible three-axis tactile sensor demonstrates the possibility of realizing normal and force measurement. These results reveal the great application prospect of tactile sensors based on multi-contact mechanism in future wearable electronics.

Flexible three-axis tactile sensor based on double-layer electrospun polyimide nanofiber membrane

Flexible three-axis tactile sensor based on double-layer electrospun polyimide nanofiber membrane

Fact-finding survey of pressure and shear force at the heel using a three-axis tactile sensor

Fact-finding survey of pressure and shear force at the heel using a three-axis tactile sensor

BaroTac: Barometric Three-Axis Tactile Sensor with Slip Detection Capability.

Tactile sensors for robotic applications enhance the performance of robotic end-effectors as they ca n provide tactile information to operate various tasks. In particular, tactile sensors can measure multi-axial force and detect slip can aid the end-effectors in grasping diverse objects in an unstructured environment. We propose BaroTac, which measures three-axial forces and detects slip with a barometric pressure sensor chip (BPSC) for robotic applications. A BPSC is an off-the-shelf commercial sensor that is inexpensive, easy to customize, robust, and simple to use. While a single BPSC-based tactile sensor can measure pressure, an array of BPSC-based tactile sensors can measure multi-axial force through the reactivity of each sensor and detect slip by observing high frequency due to slip vibration. We first experiment with defining the fundamental characteristics of a single-cell BPSC-based sensor to set the design parameters of our proposed sensor. Thereafter, we suggest the sensing method of BaroTac: calibration matrix for three-axis force measurement and discrete wavelet transform (DWT) for slip detection. Subsequently, we validate the three-axis force measuring ability and slip detectability of the fabricated multi-cell BPSC-based tactile sensor. The sensor measures three-axis force with low error (0.14, 0.18, and 0.3% in the X-, Y- and Z-axis, respectively) and discriminates slip in the high-frequency range (75-150 Hz). We finally show the practical applicability of BaroTac by installing them on the commercial robotic gripper and controlling the gripper to grasp common objects based on our sensor feedback.

Multilayered silicone foam dressings potentially used for preventing recurrence of pressure injuries: A bench-to-clinical bedside study.

This study aimed to evaluate the use of multilayered silicone foam dressings for preventing pressure injury recurrence by reducing friction, pressure, and shear force at skin sites where previous pressure injuries closed. A bench-to-clinical bedside investigation was conducted. In the bench, three multilayered silicone foam dressings were assessed. The simulated skin-shearing test consisted of a weight, a polyurethane-based skin model containing a three-axis tactile sensor, dressings, a table covered with bedsheets, and a mechanical tester. The mechanical tester simultaneously measured the interface friction force and internal shear force and pressure continuously during skin model movements. No-dressing was used as a negative control. In clinical bedside assessments, a multilayered silicone foam dressing with lower friction and shear force was applied to two bedridden patients. Photographs and ultrasound images were used to assess the recurrence of pressure injury. The dressings significantly reduced friction, pressure, and shear force compared with these parameters in the negative control. No significant differences in the shear forces between the dressings were observed. One clinical case did not develop a new pressure injury reaching the dermis. However, the second case developed a new pressure injury within one month after the first pressure injury closed. Our bench-to-clinical bedside study revealed that multilayered silicone foam dressings can potentially prevent pressure injury recurrence.

An improved BP neural network‐based calibration method for the capacitive flexible three‐axis tactile sensor array

Flexible tactile sensing based on capacitive sensing has become a research hotspot in recent years because of its low energy consumption, high performance and wide application prospects. However, the axis error caused by the coupling deformation of the dielectric will seriously affect the accuracy of the sensor. In this paper, a capacitive flexible three-axis tactile sensor array is modelled and simulated, and a neural network-based calibrator for the three-axis sensor array is proposed, which can be used to calibrate the simulated measurement data. The simulation results show that even though the correlation coefficient of linear regression for each axis is very close to 1, the effect of dielectric nonlinear coupling distortion cannot be eliminated. The calibration method based on the neural network can effectively suppress the nonlinear coupling distortion of the dielectric, and reduce the measurement coupling rate of the sensor model from 26% to 1%. At the same time, in order to ensure the measurement accuracy and robustness of different units in the sensor array, the input layer of the calibrator is expanded, and the data set containing capacitance information and two-dimensional location information is used for training. The experimental results show that the proposed calibration method combining two-dimensional position information training accurately calibrates the capacitive flexible three-dimensional tactile sensor array.

Reducing effects of dressing materials on pressure and shear force for preventing heel pressure injury: An experimental study using three-axis tactile sensor

Reducing effects of dressing materials on pressure and shear force for preventing heel pressure injury: An experimental study using three-axis tactile sensor

Capacitive Flexible Three-Axis Force Tactile Sensor Based on Porous Composite Dielectric Layer for Dexterous Robotic Manipulation

Capacitive Flexible Three-Axis Force Tactile Sensor Based on Porous Composite Dielectric Layer for Dexterous Robotic Manipulation

Detection Precision of Tangential Force Direction of CNN Aided Fingernail Color Three-axis Tactile Sensor

Detection Precision of Tangential Force Direction of CNN Aided Fingernail Color Three-axis Tactile Sensor

Precision enhancement and sensing area expansion of feeler movement typed three-axis tactile sensors

Precision enhancement and sensing area expansion of feeler movement typed three-axis tactile sensors

P89 Non-invasive Blood Pressure Measurement System Using Three-axis Tactile Force Sensor

Blood pressure is most important parameter reflecting hemodynamic factors, however it is continuously variable in 24 hours. Here, we made a non-invasive and continuous BP measurement device using a three-axis tactile force sensor. All the data was collected every 2 min for the short-term experiment, and every 10 min for the long-term experiment. In addition, the effects on the BP measurement of external physical factors such as the tension to the radial artery on applying the device and wrist circumference were evaluated. A high correlation between the measured BP with the proposed system and with the cuff-based non-invasive blood pressure, and reproducibility, were demonstrated. All data satisfied the Association for the Advancement of Medical Instrumentation criteria. The external physical factors did not affect the measurement results. In addition to previous research indicating the high reliability of the arterial pulse waveforms, the present results have demonstrated the reliability of numerical BP values, and this implies that the three-axis force sensor can be used as a patient monitoring device.

Flexible Multimodal Sensors for Electronic Skin: Principle, Materials, Device, Array Architecture, and Data Acquisition Method

Electronic skin (e-skin) is designed to mimic the comprehensive nature of human skin. Various advances in e-skin continue to drive the development of the multimodal tactile sensor technology on flexible and stretchable platforms. e-skin incorporates pressure, temperature, texture, photographic imaging, and other sensors as well as data acquisition and signal processing units formed on a soft substrate for humanoid robots, wearable devices, and health monitoring electronics that are the most critical applications of soft electronics. This artificial skin has developed very rapidly toward becoming real technology. However, the complex nature of e-skin technology presents significant challenges in terms of materials, devices, sophisticated integration methods, and interference-free data acquisition. These challenges range from functional materials, device architecture, pixel design, array structure, and data acquisition method to multimodal sensing performance with negligible interference. In this article, we present recent research trends and approaches in the field of flexible and stretchable multimodal sensors for e-skin focusing on the following aspects: 1) flexible and stretchable platforms; 2) operating principles and materials suitable for pressure, temperature, strain, photograph, and hairy sensor devices; 3) device and integration architectures, including multimodal single cells, three-axis tactile sensors, vertical-stacked sensor arrays, active matrix sensor arrays, and integration electronics; 4) reliable acquisition methods for various texture sensing and machine-learning algorithms for processing tactile sensing data; and 5) future outlook.

A Novel Three-Axial Force Tactile Sensor Based on the Fringing Effect of Electric Field

A novel flexible three-axial tactile sensor, which is composed of four interdigital capacitors, is presented in this paper. The operation of the sensor is based on the measurement of a load-induced capacitance change. For the configuration of the electrodes, four sensing electrodes and a public electrode are in the same plane, which is based on the fringing effect of the electric field. There are no floating electrodes which are beneficial to flexibility. The dielectric layer consists of air gap and polydimethylsiloxane (PDMS), and the equivalent dielectric constant of the dielectric layer will be changed when the sensor is under external force, which causes the capacitance change. Different from the existing fringing effect tactile sensor, interdigital electrodes are adopted here to enhance the sensitivity and stability of the sensor. Finite element simulation and experimental results show that there is a great enhancement in sensitivity and stability.

Reliability and Validity of Non-invasive Blood Pressure Measurement System Using Three-Axis Tactile Force Sensor.

Blood pressure (BP) is a physiological parameter reflecting hemodynamic factors and is crucial in evaluating cardiovascular disease and its prognosis. In the present study, the reliability of a non-invasive and continuous BP measurement using a three-axis tactile force sensor was verified. All the data were collected every 2 min for the short-term experiment, and every 10 min for the long-term experiment. In addition, the effects on the BP measurement of external physical factors such as the tension to the radial artery on applying the device and wrist circumference were evaluated. A high correlation between the measured BP with the proposed system and with the cuff-based non-invasive blood pressure, and reproducibility, were demonstrated. All data satisfied the Association for the Advancement of Medical Instrumentation criteria. The external physical factors did not affect the measurement results. In addition to previous research indicating the high reliability of the arterial pulse waveforms, the present results have demonstrated the reliability of numerical BP values, and this implies that the three-axis force sensor can be used as a patient monitoring device.

A Simulation Using Tacit Learning of a Robot Hand Equipped with Three-axis Tactile Sensor

A Simulation Using Tacit Learning of a Robot Hand Equipped with Three-axis Tactile Sensor

Measurement accuracy of finger shaped three-axis tactile sensor affected by back surface micro texture of skin rubber

Measurement accuracy of finger shaped three-axis tactile sensor affected by back surface micro texture of skin rubber

Flexible three-axial tactile sensors with microstructure-enhanced piezoelectric effect and specially-arranged piezoelectric arrays

Flexible tactile sensors with high sensitivity, good flexibility and the capability of measuring multidirectional forces are urgently required in modern robot technology and flexible electronic applications. Here, we present a flexible three-axial tactile sensor using piezoelectricity enhanced P(VDF-TrFE) micropillars. For achieving three-axis force measurement, the vertical aligned P(VDF-TrFE) micropillars are sandwiched between four square bottom electrodes and a common top electrode to form four symmetrically arranged piezoelectric sensing units. An elastomeric PDMS bump is fixed on the common top electrode surface to effectively transfer the contact force to the four sensing units. Taking advantage of the high sensitivity and good flexibility of the imprinted P(VDF-TrFE) micropillars, the resultant four distributed piezoelectric units are highly sensitive to the strain and can generate related signals corresponding to the compressive and tensile stress, from which the direction and the amplitude of the applied force can be deduced. The structural design, manufacturing technique，the three-axial force measuring principle, and sensing performance characterization of the proposed tactile sensor are presented in this paper. The sensitivities for X-, Y-, and Z-axis force components are calibrated as 0.3738 V N−1, 0.4146 V N−1, and 0.3443 V N−1 in experimental study. Furthermore, the proposed tactile sensor array is successfully integrated with a magnetic bar consist of NdFeB/PDMS composites to construct a magnetic actuator with sensing ability. These results give the flexible three-axial tactile sensor high potential for use in advanced robots, wearable electronics and a variety of human-machine interface implementations.

Development of robot fingers equipped with magnetic three-axis tactile sensor

Development of robot fingers equipped with magnetic three-axis tactile sensor