scholarly journals High-Porosity Foam-Based Iontronic Pressure Sensor with Superhigh Sensitivity of 9280 kPa−1

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Qingxian Liu ◽  
Yuan Liu ◽  
Junli Shi ◽  
Zhiguang Liu ◽  
Quan Wang ◽  
...  

Abstract Flexible pressure sensors with high sensitivity are desired in the fields of electronic skins, human–machine interfaces, and health monitoring. Employing ionic soft materials with microstructured architectures in the functional layer is an effective way that can enhance the amplitude of capacitance signal due to generated electron double layer and thus improve the sensitivity of capacitive-type pressure sensors. However, the requirement of specific apparatus and the complex fabrication process to build such microstructures lead to high cost and low productivity. Here, we report a simple strategy that uses open-cell polyurethane foams with high porosity as a continuous three-dimensional network skeleton to load with ionic liquid in a one-step soak process, serving as the ionic layer in iontronic pressure sensors. The high porosity (95.4%) of PU-IL composite foam shows a pretty low Young’s modulus of 3.4 kPa and good compressibility. A superhigh maximum sensitivity of 9,280 kPa−1 in the pressure regime and a high pressure resolution of 0.125% are observed in this foam-based pressure sensor. The device also exhibits remarkable mechanical stability over 5,000 compression-release or bending-release cycles. Such high porosity of composite structure provides a simple, cost-effective and scalable way to fabricate super sensitive pressure sensor, which has prominent capability in applications of water wave detection, underwater vibration sensing, and mechanical fault monitoring.

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Dong Hwan Kim ◽  
Young Jung ◽  
Kyungkuk Jung ◽  
Dong Hwa Kwak ◽  
Dong Min Park ◽  
...  

AbstractWe propose a highly sensitive capacitive pressure sensor made of hollow polydimethylsiloxane (PDMS) foam with a three-dimensional network structure. The stiffness of the foam is adjusted by the viscosity of the PDMS solution. The fabricated PDMS-30 (PDMS 30 wt%) foam shows extremely high porosity (> 86%) approximately 19 times that of bare PDMS (PDMS 100 wt%) foam. Capacitive pressure sensors fabricated using the foam possess high sensitivity, good compressibility (up to 80% strain), and consistent output characteristics in a 2000-cycle test.


RSC Advances ◽  
2021 ◽  
Vol 11 (23) ◽  
pp. 13898-13905
Author(s):  
Chuan Cai ◽  
He Gong ◽  
Weiping Li ◽  
Feng Gao ◽  
Qiushi Jiang ◽  
...  

A three-dimensional electrospun carbon nanofiber network was used to measure press strains with high sensitivity.


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.


Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 569
Author(s):  
Jianzhong Chen ◽  
Ke Sun ◽  
Rong Zheng ◽  
Yi Sun ◽  
Heng Yang ◽  
...  

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.


2021 ◽  
Vol 21 (8) ◽  
pp. 4400-4405
Author(s):  
Junyeop Lee ◽  
Nam Gon Do ◽  
Dong Hyuk Jeong ◽  
Sae-Wan Kim ◽  
Maeum Han ◽  
...  

Carbon monoxide (CO) is an odorless, colorless, tasteless, extremely flammable, and highly toxic gas. It is produced when there is insufficient oxygen supply during the combustion of carbon to produce carbon dioxide (CO2). CO is produced from operating engines, stoves, or furnaces. CO poisoning occurs when CO accumulates in the bloodstream and can result in severe tissue damage or even death. Many types of CO sensors have been reported, including electrochemical, semiconductor metal-oxide, catalytic combustion, thermal conductivity, and infrared absorption-type for the detection of CO. However, despite their excellent selectivity and sensitivity, issues such as complexity, power consumption, and calibration limit their applications. In this study, a fabricbased colorimetric CO sensor is proposed to address these issues. Potassium disulfitopalladate (II) (K2Pd(SO3)2) is dyed on a polyester fabric as a sensing material for selective CO detection. The sensing characteristics and performance are investigated using optical instruments such as RGB sensor and spectrometer. The sensor shows immediate color change when exposed to CO at a concentration that is even lower than 20 ppm before 2 min. The fast response time of the sensor is attributed to its high porosity to react with CO. This easy-to-fabricate and cost-effective sensor can detect and prevent the leakage of CO simultaneously with high sensitivity and selectivity toward CO.


Author(s):  
Jiang Zhao ◽  
Jiahao Gui ◽  
Jinsong Luo ◽  
Jing Gao ◽  
Caidong Zheng ◽  
...  

Abstract Graphene-based pressure sensors have received extensive attention in wearable devices. However, reliable, low-cost, and large-scale preparation of structurally stable graphene electrodes for flexible pressure sensors is still a challenge. Herein, for the first time, laser-induced graphene (LIG) powder are prepared into screen printing ink, and shape-controllable LIG patterned electrodes can be obtained on various substrates using a facile screen printing process, and a novel asymmetric pressure sensor composed of the resulting screen-printed LIG electrodes has been developed. Benefit from the 3D porous structure of LIG, the as-prepared flexible LIG screen-printed asymmetric pressure sensor has super sensing properties with a high sensitivity of 1.86 kPa−1, low detection limit of about 3.4 Pa, short response time, and long cycle durability. Such excellent sensing performances give our flexible asymmetric LIG screen-printed pressure sensor the ability to realize real-time detection of tiny body physiological movements (such as wrist pulse and pronunciation action). Besides, the integrated sensor array has a multi-touch function. This work could stimulate an appropriate approach to designing shape-controllable LIG screen-printed patterned electrodes on various flexible substrates to adapt the specific needs of fulfilling compatibility and modular integration for potential application prospects in wearable electronics.


2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000373-000378
Author(s):  
R. Otmani ◽  
N. Benmoussa ◽  
K. Ghaffour

Piezoresistive pressure sensors based on Silicon have a large thermal drift because of their high sensitivity to temperature (ten times more sensitive to temperature than metals). So the study of the thermal behavior of these sensors is essential to define the parameters that cause the drift of the output characteristics. In this study, we adopted the behavior of 2nd degree gauges depending on the temperature. Then we model the thermal behavior of the sensor and its characteristics.


Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 664 ◽  
Author(s):  
Junsong Hu ◽  
Junsheng Yu ◽  
Ying Li ◽  
Xiaoqing Liao ◽  
Xingwu Yan ◽  
...  

The reasonable design pattern of flexible pressure sensors with excellent performance and prominent features including high sensitivity and a relatively wide workable linear range has attracted significant attention owing to their potential application in the advanced wearable electronics and artificial intelligence fields. Herein, nano carbon black from kerosene soot, an atmospheric pollutant generated during the insufficient burning of hydrocarbon fuels, was utilized as the conductive material with a bottom interdigitated textile electrode screen printed using silver paste to construct a piezoresistive pressure sensor with prominent performance. Owing to the distinct loose porous structure, the lumpy surface roughness of the fabric electrodes, and the softness of polydimethylsiloxane, the piezoresistive pressure sensor exhibited superior detection performance, including high sensitivity (31.63 kPa−1 within the range of 0–2 kPa), a relatively large feasible range (0–15 kPa), a low detection limit (2.26 pa), and a rapid response time (15 ms). Thus, these sensors act as outstanding candidates for detecting the human physiological signal and large-scale limb movement, showing their broad range of application prospects in the advanced wearable electronics field.


Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1412 ◽  
Author(s):  
Young Jung ◽  
Wookjin Lee ◽  
Kyungkuk Jung ◽  
Byunggeon Park ◽  
Jinhyoung Park ◽  
...  

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.


Sensor Review ◽  
2020 ◽  
Vol 40 (5) ◽  
pp. 529-534
Author(s):  
Igor S. Nadezhdin ◽  
Aleksey G. Goryunov

Purpose Differential pressure is an important technological parameter, one urgent task of which is control and measurement. To date, the lion’s share of research in this area has focused on the development and improvement of differential pressure sensors. The purpose of this paper is to develop a smart differential pressure sensor with improved operational and metrological characteristics. Design/methodology/approach The operating principle of the developed pressure sensor is based on the capacitive measurement principle. The measuring unit of the developed pressure sensor is based on a differential capacitive sensitive element. Programmable system-on-chip (PSoC) technology has been used to develop the electronics unit. Findings The use of a differential capacitive sensitive element allows the unit to compensate for the influence of interference (for example, temperature) on the measurement result. With the use of PSoC technology, it is also possible to increase the noise immunity of the developed smart differential pressure sensor and provide an unparalleled combination of flexibility and integration of analog and digital functionality. Originality/value The use of PSoC technology in the developed smart differential pressure sensor has many indisputable advantages, as the size of the entire circuit can be minimized. As a result, the circuit has improved noise immunity. Accordingly, the procedure for debugging and changing the software of the electronics unit is simplified. These features make development and manufacturing cost effective.


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