scholarly journals Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 824
Author(s):  
Byunggeon Park ◽  
Young Jung ◽  
Jong Soo Ko ◽  
Jinhyoung Park ◽  
Hanchul Cho
Keyword(s):  
Porous Structure ◽  
Shape Memory ◽  
Pressure Sensor ◽  
Shape Memory Polymer ◽  
Three Dimensional ◽  
Pressure Sensors ◽  
Capacitive Pressure Sensor ◽  
Practical Applications ◽  
Flexible Pressure Sensor ◽  
Sensing Performance

Highly flexible and compressible porous polyurethane (PU) structures have effectively been applied in capacitive pressure sensors because of the good elastic properties of the PU structures. However, PU porous structure-based pressure sensors have been limited in practical applications owing to their low durability during pressure cycling. Herein, we report a flexible pressure sensor based on a three-dimensional porous structure with notable durability at a compressive pressure of 500 kPa facilitated by the use of a shape memory polymer (SMP). The SMP porous structure was fabricated using a sugar templating process and capillary effect. The use of the SMP resulted in the maintenance of the sensing performance for 100 cycles at 500 kPa; the SMP can restore its original shape within 30 s of heating at 80 °C. The pressure sensor based on the SMP exhibited a higher sensitivity of 0.0223 kPa−1 than a typical PU-based sensor and displayed excellent sensing performance in terms of stability, response time, and hysteresis. Additionally, the proposed sensor was used to detect shoe insole pressures in real time and exhibited remarkable durability and motion differentiation.

scholarly journals A Highly Sensitive and Flexible Capacitive Pressure Sensor Based on a Porous Three-Dimensional PDMS/Microsphere Composite

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1412 ◽  
Author(s):  
Young Jung ◽  
Wookjin Lee ◽  
Kyungkuk Jung ◽  
Byunggeon Park ◽  
Jinhyoung Park ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Sacrificial Layer ◽  
Three Dimensional ◽  
Pressure Sensors ◽  
Capacitive Pressure Sensor ◽  
Mechanical Stimuli ◽  
Highly Sensitive ◽  
Flexible Pressure Sensors ◽  
Fast Rise ◽  
Better Than

In recent times, polymer-based flexible pressure sensors have been attracting a lot of attention because of their various applications. A highly sensitive and flexible sensor is suggested, capable of being attached to the human body, based on a three-dimensional dielectric elastomeric structure of polydimethylsiloxane (PDMS) and microsphere composite. This sensor has maximal porosity due to macropores created by sacrificial layer grains and micropores generated by microspheres pre-mixed with PDMS, allowing it to operate at a wider pressure range (~150 kPa) while maintaining a sensitivity (of 0.124 kPa−1 in a range of 0~15 kPa) better than in previous studies. The maximized pores can cause deformation in the structure, allowing for the detection of small changes in pressure. In addition to exhibiting a fast rise time (~167 ms) and fall time (~117 ms), as well as excellent reproducibility, the fabricated pressure sensor exhibits reliability in its response to repeated mechanical stimuli (2.5 kPa, 1000 cycles). As an application, we develop a wearable device for monitoring repeated tiny motions, such as the pulse on the human neck and swallowing at the Adam’s apple. This sensory device is also used to detect movements in the index finger and to monitor an insole system in real-time.

scholarly journals Multi-Material 3D Printed Shape Memory Polymer with Tunable Melting and Glass Transition Temperature Activated by Heat or Light

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 710 ◽  
Author(s):  
Ela Sachyani Keneth ◽  
Rama Lieberman ◽  
Matthew Rednor ◽  
Giulia Scalet ◽  
Ferdinando Auricchio ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Shape Memory ◽  
Smart Materials ◽  
Shape Memory Polymer ◽  
3D Structure ◽  
Three Dimensional ◽  
Shape Memory Polymers ◽  
Practical Applications ◽  
Different Temperatures ◽  
Robotic Devices

Shape memory polymers are attractive smart materials that have many practical applications and academic interest. Three-dimensional (3D) printable shape memory polymers are of great importance for the fabrication of soft robotic devices due to their ability to build complex 3D structures with desired shapes. We present a 3D printable shape memory polymer, with controlled melting and transition temperature, composed of methacrylated polycaprolactone monomers and N-Vinylcaprolactam reactive diluent. Tuning the ratio between the monomers and the diluents resulted in changes in melting and transition temperatures by 20, and 6 °C, respectively. The effect of the diluent addition on the shape memory behavior and mechanical properties was studied, showing above 85% recovery ratio, and above 90% fixity, when the concentration of the diluent was up to 40 wt %. Finally, we demonstrated multi-material printing of a 3D structure that can be activated locally, at two different temperatures, by two different stimuli; direct heating and light irradiation. The remote light activation was enabled by utilizing a coating of Carbon Nano Tubes (CNTs) as an absorbing material, onto sections of the printed objects.

scholarly journals Printed and Flexible Capacitive Pressure Sensor with Carbon Nanotubes based Composite Dielectric Layer

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 715 ◽  
Author(s):  
Zhenxin Guo ◽  
Lixin Mo ◽  
Yu Ding ◽  
Qingqing Zhang ◽  
Xiangyou Meng ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Pressure Sensor ◽  
Dielectric Layer ◽  
Pressure Sensors ◽  
Weight Fraction ◽  
Capacitive Pressure Sensor ◽  
Flexible Pressure Sensor ◽  
Flexible Pressure Sensors

Flexible pressure sensors have attracted tremendous attention from researchers for their widely applications in tactile artificial intelligence, electric skin, disease diagnosis, and healthcare monitoring. Obtaining flexible pressure sensors with high sensitivity in a low cost and convenient way remains a huge challenge. In this paper, the composite dielectric layer based on the mixture of carbon nanotubes (CNTs) with different aspect ratios and polydimethylsiloxane (PDMS) was employed in flexible capacitive pressure sensor to increase its sensitivity. In addition, the screen printing instead of traditional etching based methods was used to prepare the electrodes array of the sensor. The results showed that the aspect ratio and weight fraction of the CNTs play an important role in improving the sensitivity of the printed capacitive pressure sensor. The prepared capacitive sensor with the CNTs/PDMS composite dielectric layer demonstrated a maximum sensitivity of 2.9 kPa−1 in the pressure range of 0–450 Pa, by using the CNTs with an aspect ratio of 1250–3750 and the weight fraction of 3.75%. The mechanism study revealed that the increase of the sensitivity of the pressure sensor should be attributed to the relative permittivity increase of the composite dielectric layer under pressure. Meanwhile, the printed 3 × 3 and 10 × 10 sensor arrays showed excellent spatial resolution and uniformity when they were applied to measure the pressure distribution. For further applications, the flexible pressure sensor was integrated on an adhesive bandage to detect the finger bending, as well as used to create Morse code by knocking the sensor to change their capacitance curves. The printed and flexible pressure sensor in this study might be a good candidate for the development of tactile artificial intelligence, intelligent medical diagnosis systems and wearable electronics.

Development of circuit solution and design of capacitive pressure sensor array for applied robotics

2020 ◽  
Vol 8 (4) ◽  
pp. 296-307
Author(s):  
Konstantin Krestovnikov ◽  
Aleksei Erashov ◽  
Аleksandr Bykov
Keyword(s):  
Pressure Sensor ◽  
Output Signal ◽  
Sensor Array ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Fine Tuning ◽  
Capacitive Pressure Sensor ◽  
Cell Parameters ◽  
Linear Pattern ◽  
Sensor Structure

This paper presents development of pressure sensor array with capacitance-type unit sensors, with scalable number of cells. Different assemblies of unit pressure sensors and their arrays were considered, their characteristics and fabrication methods were investigated. The structure of primary pressure transducer (PPT) array was presented; its operating principle of array was illustrated, calculated reference ratios were derived. The interface circuit, allowing to transform the changes in the primary transducer capacitance into voltage level variations, was proposed. A prototype sensor was implemented; the dependency of output signal power from the applied force was empirically obtained. In the range under 30 N it exhibited a linear pattern. The sensitivity of the array cells to the applied pressure is in the range 134.56..160.35. The measured drift of the output signals from the array cells after 10,000 loading cycles was 1.39%. For developed prototype of the pressure sensor array, based on the experimental data, the average signal-to-noise ratio over the cells was calculated, and equaled 63.47 dB. The proposed prototype was fabricated of easily available materials. It is relatively inexpensive and requires no fine-tuning of each individual cell. Capacitance-type operation type, compared to piezoresistive one, ensures greater stability of the output signal. The scalability and adjustability of cell parameters are achieved with layered sensor structure. The pressure sensor array, presented in this paper, can be utilized in various robotic systems.

Three-dimensional Graphene Coated Shape Memory Polyurethane Foam with Fast Responsive Performance

2021 ◽  
Author(s):  
Tianjiao Wang ◽  
Jun Zhao ◽  
Chuanxin Weng ◽  
Tong Wang ◽  
Yayun Liu ◽  
...  
Keyword(s):  
Shape Memory ◽  
Polyurethane Foam ◽  
Three Dimensional ◽  
Shape Memory Polymers ◽  
Practical Applications ◽  
External Stimuli ◽  
Shape Memory Polyurethane

Shape memory polymers (SMPs) that change shapes as designed by external stimuli have become one of the most promising materials as actuators, sensors, and deployable devices. However, their practical applications...

scholarly journals Three-Dimensional Arterial Pulse Signal Acquisition in Time Domain Using Flexible Pressure-Sensor Dense Arrays

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 569
Author(s):  
Jianzhong Chen ◽  
Ke Sun ◽  
Rong Zheng ◽  
Yi Sun ◽  
Heng Yang ◽  
...  
Keyword(s):  
Radial Artery ◽  
Pressure Sensor ◽  
Pulse Width ◽  
Printed Circuit Boards ◽  
Color Doppler ◽  
Three Dimensional ◽  
Pressure Sensors ◽  
Sensor Arrays ◽  
Signal Acquisition ◽  
Dynamic Pulse

In this study, we developed a radial artery pulse acquisition system based on finger-worn dense pressure sensor arrays to enable three-dimensional pulse signals acquisition. The finger-worn dense pressure-sensor arrays were fabricated by packaging 18 ultra-small MEMS pressure sensors (0.4 mm × 0.4 mm × 0.2 mm each) with a pitch of 0.65 mm on flexible printed circuit boards. Pulse signals are measured and recorded simultaneously when traditional Chinese medicine practitioners wear the arrays on the fingers while palpating the radial pulse. Given that the pitches are much smaller than the diameter of the human radial artery, three-dimensional pulse envelope images can be measured with the system, as can the width and the dynamic width of the pulse signals. Furthermore, the array has an effective span of 11.6 mm—3–5 times the diameter of the radial artery—which enables easy and accurate positioning of the sensor array on the radial artery. This study also outlines proposed methods for measuring the pulse width and dynamic pulse width. The dynamic pulse widths of three volunteers were measured, and the dynamic pulse width measurements were consistent with those obtained by color Doppler ultrasound. The pulse wave velocity can also be measured with the system by measuring the pulse transit time between the pulse signals at the brachial and radial arteries using the finger-worn sensor arrays.

scholarly journals Noncovalent π-stacked robust topological organic framework

2020 ◽  
Vol 117 (34) ◽  
pp. 20397-20403
Author(s):  
Dong Meng ◽  
Jonathan Lee Yang ◽  
Chengyi Xiao ◽  
Rui Wang ◽  
Xiaofei Xing ◽  
...  
Keyword(s):  
Porous Structure ◽  
Organic Semiconductors ◽  
Organic Electronics ◽  
High Performance ◽  
Three Dimensional ◽  
Self Healing ◽  
Direct Construction ◽  
Covalent Bonds ◽  
Practical Applications ◽  
Organic Framework

Organic frameworks (OFs) offer a novel strategy for assembling organic semiconductors into robust networks that facilitate transport, especially the covalent organic frameworks (COFs). However, poor electrical conductivity through covalent bonds and insolubility of COFs limit their practical applications in organic electronics. It is known that the two-dimensional intralayer π∙∙∙π transfer dominates transport in organic semiconductors. However, because of extremely labile inherent features of noncovalent π∙∙∙π interaction, direct construction of robust frameworks via noncovalent π∙∙∙π interaction is a difficult task. Toward this goal, we report a robust noncovalent π∙∙∙π interaction-stacked organic framework, namely πOF, consisting of a permanent three-dimensional porous structure that is held together by pure intralayer noncovalent π∙∙∙π interactions. The elaborate porous structure, with a 1.69-nm supramaximal micropore, is composed of fully conjugated rigid aromatic tetragonal-disphenoid-shaped molecules with four identical platforms. πOF shows excellent thermostability and high recyclability and exhibits self-healing properties by which the parent porosity is recovered upon solvent annealing at room temperature. Taking advantage of the long-range π∙∙∙π interaction, we demonstrate remarkable transport properties of πOF in an organic-field-effect transistor, and the mobility displays relative superiority over the traditional COFs. These promising results position πOF in a direction toward porous and yet conductive materials for high-performance organic electronics.

A flexible pressure sensor based on an MXene–textile network structure

2019 ◽  
Vol 7 (4) ◽  
pp. 1022-1027 ◽  
Author(s):  
Tongkuai Li ◽  
Longlong Chen ◽  
Xiang Yang ◽  
Xin Chen ◽  
Zhihan Zhang ◽  
...  
Keyword(s):  
Network Structure ◽  
Pressure Sensor ◽  
High Performance ◽  
Pressure Sensors ◽  
Wearable Electronics ◽  
Physiological Signal ◽  
Signal Perception ◽  
Performance Pressure ◽  
Human Machine Interfaces ◽  
Flexible Pressure Sensor

High-performance pressure sensors have attracted considerable attention recently due to their promising applications in touch displays, wearable electronics, human–machine interfaces, and real-time physiological signal perception.

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