scholarly journals A Carbon Nanotube–Metal Oxide Hybrid Material for Visible-Blind Flexible UV-Sensor

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 368
Author(s):  
Pawan Pathak ◽  
Sanghoon Park ◽  
Hyoung Jin Cho

Flexible sensors with low fabrication cost, high sensitivity, and good stability are essential for the development of smart devices for wearable electronics, soft robotics, and electronic skins. Herein, we report a nanocomposite material based on carbon nanotube and metal oxide semiconductor for ultraviolet (UV) sensing applications, and its sensing behavior. The sensors were prepared by a screen-printing process under a low-temperature curing condition. The formation of a conducting string node and a sensing node could enhance a UV sensing response, which could be attributed to the uniform mixing of functionalized multi-walled carbon nanotubes and zinc oxide nanoparticles. A fabricated device has shown a fast response time of 1.2 s and a high recovery time of 0.8 s with good mechanical stability.

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1941 ◽  
Author(s):  
Yousef Al-Handarish ◽  
Olatunji Mumini Omisore ◽  
Wenke Duan ◽  
Jing Chen ◽  
Luo Zebang ◽  
...  

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.


2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Jung Joon Lee ◽  
Srinivas Gandla ◽  
Byeongjae Lim ◽  
Sunju Kang ◽  
Sunyoung Kim ◽  
...  

Abstract Conformal and ultrathin coating of highly conductive PEDOT:PSS on hydrophobic uneven surfaces is essential for resistive-based pressure sensor applications. For this purpose, a water-based poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) solution was successfully exchanged to an organic solvent-based PEDOT:PSS solution without any aggregation or reduction in conductivity using the ultrafiltration method. Among various solvents, the ethanol (EtOH) solvent-exchanged PEDOT:PSS solution exhibited a contact angle of 34.67°, which is much lower than the value of 96.94° for the water-based PEDOT:PSS solution. The optimized EtOH-based PEDOT:PSS solution exhibited conformal and uniform coating, with ultrathin nanocoated films obtained on a hydrophobic pyramid polydimethylsiloxane (PDMS) surface. The fabricated pressure sensor showed high performances, such as high sensitivity (−21 kPa−1 in the low pressure regime up to 100 Pa), mechanical stability (over 10,000 cycles without any failure or cracks) and a fast response time (90 ms). Finally, the proposed pressure sensor was successfully demonstrated as a human blood pulse rate sensor and a spatial pressure sensor array for practical applications. The solvent exchange process using ultrafiltration for these applications can be utilized as a universal technique for improving the coating property (wettability) of conducting polymers as well as various other materials.


2015 ◽  
Vol 10 (1) ◽  
pp. 13-20
Author(s):  
Elisabete Galeazzo ◽  
Marcos C. Moraes ◽  
Henrique E. M. Peres ◽  
Michel O. S. Dantas ◽  
Victor G. C. Lobo ◽  
...  

Intensive research has been focused on investigating new sensing materials, such as carbon nanotubes (CNT) because of their promising characteristics. However, there are challenges related to their application in commercial devices such as sensitivity, compatibility, and complexity of miniaturization, among others. We report the study of the electrical behavior of devices composed by multi-walled carbon nanotubes (MWCNT) deposited between aluminum electrodes on glass substrates by means of dielectrophoresis (DEP), which is a simple and cost-effective method. The devices were fabricated by varying the DEP process time. Remarkable changes in their electric resistance were noticed depending on the MWCNT quantities deposited. Other electrical properties of devices such as high sensitivity, fast response time and stability are also characterized in humid environment. A humidity sensing mechanism is proposed on the basis of charge transfer between adsorbed water molecules and the MWNTC surface or between water and the glass surface.


2021 ◽  
Author(s):  
Jihyun Lee ◽  
Youngmoon Choi ◽  
Byoung Joon Park ◽  
Jeong Woo Han ◽  
Hyun-Sook Lee ◽  
...  

Abstract ZnO has been studied intensely for chemical sensors due to its high sensitivity and fast response. Here, we present a simple approach to precisely control oxygen vacancy contents to provide significantly enhanced acetone sensing performance of commercial ZnO nanopowders. A combination of H2O2 treatment and thermal annealing produces optimal surface defects with oxygen vacancies on the ZnO nanoparticles (NPs). The highest response of ~27,562 was achieved for 10 ppm acetone in 0.125 M H2O2 treated/annealed ZnO NPs at the optimal working temperature of 400 ℃, which is significantly higher than that of reported so far in various acetone sensors based on metal-oxide-semiconductor (MOS). Furthermore, first-principles calculations indicate that pre-adsorbed O formed on the surface of H2O2-treated ZnO NPs can provide a favorable adsorption energy, especially for acetone detection, due to strong bidentate bonding between carbonyl C atom of acetone molecules and pre-adsorbed O on the ZnO surface. Our study demonstrates that controlling surface oxygen vacancies by H2O2 treatment and re-annealing at optimal temperature is an effective method to improve the sensing properties of commercial MOS materials.


2019 ◽  
Vol 6 (1) ◽  
pp. 1900845 ◽  
Author(s):  
Kyung‐Tae Kim ◽  
Seung‐Han Kang ◽  
Jaeyoung Kim ◽  
Jae Sang Heo ◽  
Yong‐Hoon Kim ◽  
...  

RSC Advances ◽  
2020 ◽  
Vol 10 (44) ◽  
pp. 26188-26196 ◽  
Author(s):  
Xiaojun Chen ◽  
Xitong Lin ◽  
Deyun Mo ◽  
Xiaoqun Xia ◽  
Manfeng Gong ◽  
...  

Bionic electronic skin with human sensory capabilities has attracted extensive research interest, which has been applied in the fields of medical health diagnosis, wearable electronics, human–computer interaction, and bionic prosthetics.


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