Photolithography-assisted precise patterning of nanocracks for ultrasensitive strain sensors

2021 ◽  
Vol 9 (7) ◽  
pp. 4262-4272
Author(s):  
Junshan Liu ◽  
Hongji Guo ◽  
Ming Li ◽  
Chi Zhang ◽  
Yongzhi Chu ◽  
...  
Keyword(s):  
Strain Sensor ◽  
Strain Range ◽  
Metal Films ◽  
Strain Sensors ◽  
Gauge Factor

A photolithography-assisted nanocrack patterning method is reported to precisely define the nanocrack pattern in metal films. This method is used to fabricate an ultrasensitive strain sensor with a gauge factor of ∼20 000 in 0–1.2% strain range.

scholarly journals Ultrasensitive Strain Sensor Based on Pre-Generated Crack Networks Using Ag Nanoparticles/Single-Walled Carbon Nanotube (SWCNT) Hybrid Fillers and a Polyester Woven Elastic Band

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2531
Author(s):  
Yelin Ko ◽  
Ji-seon Kim ◽  
Chi Cuong Vu ◽  
Jooyong Kim
Keyword(s):  
High Performance ◽  
Strain Sensor ◽  
Strain Range ◽  
Human Motion ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Elastic Band ◽  
Practical Applications ◽  
Single Walled Carbon ◽  
Novel Strategy

Flexible strain sensors are receiving a great deal of interest owing to their prospective applications in monitoring various human activities. Among various efforts to enhance the sensitivity of strain sensors, pre-crack generation has been well explored for elastic polymers but rarely on textile substrates. Herein, a highly sensitive textile-based strain sensor was fabricated via a dip-coat-stretch approach: a polyester woven elastic band was dipped into ink containing single-walled carbon nanotubes coated with silver paste and pre-stretched to generate prebuilt cracks on the surface. Our sensor demonstrated outstanding sensitivity (a gauge factor of up to 3550 within a strain range of 1.5–5%), high stability and durability, and low hysteresis. The high performance of this sensor is attributable to the excellent elasticity and woven structure of the fabric substrate, effectively generating and propagating the prebuilt cracks. The strain sensor integrated into firefighting gloves detected detailed finger angles and cyclic finger motions, demonstrating its capability for subtle human motion monitoring. It is also noteworthy that this novel strategy is a very quick, straightforward, and scalable method of fabricating strain sensors, which is extremely beneficial for practical applications.

scholarly journals High-Performance Wearable Strain Sensor Based on MXene@Cotton Fabric with Network Structure

2021 ◽  
Author(s):  
Lu Liu ◽  
Libo Wang ◽  
Xuqing Liu ◽  
Wenfeng Yuan ◽  
Mengmeng Yuan ◽  
...  
Keyword(s):  
Cotton Fabric ◽  
High Performance ◽  
Mechanical Performance ◽  
Active Material ◽  
Large Body ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Gauge Factor

Abstract Although 2D nanomaterials such as MXene Ti3C2Tx have been used in flexible electronic devices for their unique properties such as high conductivity, excellent mechanical performance, flexibility, and good hydrophilicity, less research has focused on of MXene-based cotton fabric strain sensors. Moreover, fabrication of wearable strain sensors with a low cost, high sensitivity, good biocompatibility, and broad sensing range is still a challenge. In this work, a high-performance wearable strain sensor composed of 2D MXene d-Ti3C2Tx nanomaterials and cotton fabric is reported. As the active material in the sensor, MXene d-Ti3C2Tx exhibited an excellent conductivity and hydrophilicity and adhered well to the fabric fibers by electrostatic adsorption. Due to the unique structure of the fabric substrate and the properties of MXene sheets, the fabricated pressure sensor achieved a high sensitivity. The gauge factor of the MXene@cotton fabric strain sensor reached up to 4.11 within the strain range of 15 %. Meanwhile, the sensor possessed high durability (>500 cycles) and a low strain detection limit of 0.3%. Finally, the encapsulated strain sensor was used to detect subtle or large body movements and exhibited a rapid response. This study shows that the MXene@cotton fabric strain sensor reported here have great potential for use in flexible, comfortable, and wearable devices for health monitoring and motion detection.

scholarly journals Nano-Cracked Strain Sensor with High Sensitivity and Linearity by Controlling the Crack Arrangement

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2834 ◽  
Author(s):  
Hyunsuk Jung ◽  
Chan Park ◽  
Hyunwoo Lee ◽  
Seonguk Hong ◽  
Hyonguk Kim ◽  
...  
Keyword(s):  
Pulse Wave ◽  
Wearable Sensors ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Micro Deformation ◽  
Sensing Performance ◽  
Limited Sensitivity

Studies on wearable sensors that monitor various movements by attaching them to a body have received considerable attention. Crack-based strain sensors are more sensitive than other sensors. Owing to their high sensitivity, these sensors have been investigated for measuring minute deformations occurring on the skin, such as pulse. However, existing studies have limited sensitivity at low strain range and nonlinearity that renders any calibration process complex and difficult. In this study, we propose a pre-strain and sensor-extending process to improve the sensitivity and linearity of the sensor. By using these pre-strain and sensor-extending processes, we were able to control the morphology and alignment of cracks and regulate the sensitivity and linearity of the sensor. Even if the sensor was fabricated in the same manner, the sensor that involved the pre-strain and extending processes had a sensitivity 100 times greater than normal sensors. Thus, our crack-based strain sensor had high sensitivity (gauge factor > 5000, gauge factor (GF = (△R/R0)/ε), linearity, and low hysteresis at low strain (<1% strain). Given its high sensing performance, the sensor can be used to measure micro-deformation, such as pulse wave and voice.

3D-Printed Stretchable Strain Sensor With Application to Wind Sensing

2018 ◽  
Author(s):  
Mohammed Al-Rubaiai ◽  
Ryohei Tsuruta ◽  
Umesh Gandhi ◽  
Chuan Wang ◽  
Xiaobo Tan
Keyword(s):  
Wind Speed ◽  
Large Strain ◽  
Thermoplastic Polyurethane ◽  
Strain Sensor ◽  
Strain Range ◽  
Strain Sensors ◽  
Plastic Substrate ◽  
Gauge Factor ◽  
Effective Manner ◽  
3D Printed

Stretchable strain sensors with large strain range, high sensitivity, and excellent reliability are of great interest for applications in soft robotics, wearable devices, and structure-monitoring systems. Unlike conventional template lithography-based approaches, 3D-printing can be used to fabricate complex devices in a simple and cost-effective manner. In this paper, we report 3D-printed stretchable strain sensors that embeds a flexible conductive composite material in a hyper-plastic substrate. Three commercially available conductive filaments are explored, among which the conductive thermoplastic polyurethane (ETPU) shows the highest sensitivity (gauge factor of 5), with a working strain range of 0%–20%. The ETPU strain sensor exhibits an interesting behavior where the conductivity increases with the strain. In addition, an experiment for measuring the wind speed is conducted inside a wind tunnel, where the ETPU sensor shows sensitivity to the wind speed beyond 5.6 m/s.

scholarly journals A Practical Strain Sensor Based on Ecoflex/Overlapping Graphene/Ecoflex Sandwich Structures for Vocal Fold Vibration and Body Motion Monitoring

2022 ◽  
Vol 2 ◽  
Author(s):  
Yanyan Fan ◽  
Hongbin Zhao ◽  
Yifan Yang ◽  
Yi Yang ◽  
Tianling Ren ◽  
...  
Keyword(s):  
Structural Design ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Body Motion ◽  
Gauge Factor ◽  
Sensing Element ◽  
Structure Deformation ◽  
Vocal Fold Vibration

Graphene-based stretchable and flexible strain sensors are one of the promising “bridges” to the biomedical realm. However, enhancing graphene-based wearable strain sensors to meet the demand of high sensitivity, broad sensing range, and recoverable structure deformation simultaneously is still a great challenge. In this work, through structural design, we fabricated a simple Ecoflex/Overlapping Graphene/Ecoflex (EOGE) strain sensor by encapsulating a graphene sensing element on polymer Ecoflex substrates using a drop-casting method. The EOGE strain sensor can detect stretching with high sensitivity, a maximum gauge factor of 715 with a wide strain range up to 57%, and adequate reliability and stability over 1,000 cycles for stretching. Moreover, the EOGE strain sensor shows recoverable structure deformation, and the sensor has a steady response in the frequency disturbance test. The good property of the strain sensor is attributed to the resistance variation induced by the overlap and crack structure of graphene by structural design. The vibrations caused by sound and various body movements have been thoroughly detected, which exhibited that the EOGE strain sensor is a promising candidate for wearable biomedical electronic applications.

scholarly journals Fabrication and Performance Evaluation of Highly Sensitive Flexible Strain Sensors with Aligned Silver Nanowires

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 156 ◽  
Author(s):  
Jae Hyuk Choi ◽  
Myung Gyu Shin ◽  
Young Jung ◽  
Dong Hwan Kim ◽  
Jong Soo Ko
Keyword(s):  
Silver Nanowires ◽  
Low Cost ◽  
Strain Sensor ◽  
Strain Range ◽  
Longitudinal Direction ◽  
Dip Coating ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Lateral Direction ◽  
And Performance

In this study, we fabricated strain sensors by aligning silver nanowires and transferring them with polydimethylsiloxane (PDMS) and compared the performances of the fabricated strain sensors along the alignment direction. Two types of flexible strain sensors embedded with the aligned silver nanowires were fabricated: one in the longitudinal direction, which is the same as the alignment direction, and the other in the lateral direction, which is perpendicular to the alignment direction. We then evaluated their properties. The proposed longitudinally aligned strain sensor showed the maximum sensitivity (gauge factor (GF) = 89.99) under 25% tensile conditions, which is 7.08 times higher than the sensitivity (GF = 12.71) shown by the laterally aligned strain sensor under 25% tensile conditions. This finding confirmed that the alignment direction of silver nanowires influences the sensitivity of flexible strain sensors. Furthermore, this study demonstrates that the laterally aligned strain sensor (ε > 60%) can be used in wearable devices because it satisfies the required strain range (ε > 50%). Since the strain sensors were fabricated using the temperature-controlled dip coating process, they can be produced at low cost in large quantities, and thus they have advantages for commercialization. These characteristics will be applicable to various flexible devices as well as to flexible strain sensors.

scholarly journals Development of Highly Sensitive Strain Sensor Using Area-Arrayed Graphene Nanoribbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1701
Author(s):  
Ken Suzuki ◽  
Ryohei Nakagawa ◽  
Qinqiang Zhang ◽  
Hideo Miura
Keyword(s):  
Graphene Nanoribbons ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Sensitive Strain ◽  
Bending Test ◽  
Gauge Factor ◽  
Four Point Bending ◽  
Current Voltage ◽  
Highly Sensitive ◽  
Current Voltage Relationship

In this study, a basic design of area-arrayed graphene nanoribbon (GNR) strain sensors was proposed to realize the next generation of strain sensors. To fabricate the area-arrayed GNRs, a top-down approach was employed, in which GNRs were cut out from a large graphene sheet using an electron beam lithography technique. GNRs with widths of 400 nm, 300 nm, 200 nm, and 50 nm were fabricated, and their current-voltage characteristics were evaluated. The current values of GNRs with widths of 200 nm and above increased linearly with increasing applied voltage, indicating that these GNRs were metallic conductors and a good ohmic junction was formed between graphene and the electrode. There were two types of GNRs with a width of 50 nm, one with a linear current–voltage relationship and the other with a nonlinear one. We evaluated the strain sensitivity of the 50 nm GNR exhibiting metallic conduction by applying a four-point bending test, and found that the gauge factor of this GNR was about 50. Thus, GNRs with a width of about 50 nm can be used to realize a highly sensitive strain sensor.

scholarly journals A Novel Textile Stitch-Based Strain Sensor for Wearable End Users

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1469 ◽  
Author(s):  
Orathai Tangsirinaruenart ◽  
George Stylios
Keyword(s):  
Mechanical Properties ◽  
Electrical Resistance ◽  
Body Movement ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Heart Monitoring ◽  
Textile Sensors ◽  
Good Repeatability ◽  
The Ideal

This research presents an investigation of novel textile-based strain sensors and evaluates their performance. The electrical resistance and mechanical properties of seven different textile sensors were measured. The sensors are made up of a conductive thread, composed of silver plated nylon 117/17 2-ply, 33 tex and 234/34 4-ply, 92 tex and formed in different stitch structures (304, 406, 506, 605), and sewn directly onto a knit fabric substrate (4.44 tex/2 ply, with 2.22, 4.44 and 7.78 tex spandex and 7.78 tex/2 ply, with 2.22 and 4.44 tex spandex). Analysis of the effects of elongation with respect to resistance indicated the ideal configuration for electrical properties, especially electrical sensitivity and repeatability. The optimum linear working range of the sensor with minimal hysteresis was found, and the sensor’s gauge factor indicated that the sensitivity of the sensor varied significantly with repeating cycles. The electrical resistance of the various stitch structures changed significantly, while the amount of drift remained negligible. Stitch 304 2-ply was found to be the most suitable for strain movement. This sensor has a wide working range, well past 50%, and linearity (R2 is 0.984), low hysteresis (6.25% ΔR), good gauge factor (1.61), and baseline resistance (125 Ω), as well as good repeatability (drift in R2 is −0.0073). The stitch-based sensor developed in this research is expected to find applications in garments as wearables for physiological wellbeing monitoring such as body movement, heart monitoring, and limb articulation measurement.

scholarly journals A novel strain sensor using a microchannel embedded in PDMS

2018 ◽  
Vol 4 (2) ◽  
pp. 1 ◽  
Author(s):  
Angelica Campigotto ◽  
Stephane Leahy ◽  
Ayan Choudhury ◽  
Guowei Zhao ◽  
Yongjun Lai
Keyword(s):  
Finite Element ◽  
Rotation Angle ◽  
Strain Sensor ◽  
Element Model ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Sectional Area ◽  
Cross Sectional ◽  
Higher Sensitivity

A novel, inexpensive, and easy-to-use strain sensor using polydimethylsiloxane (PDMS)  was developed. The sensor consists of a microchannel that is partially filled with a coloured liquid and embedded in a piece of PDMS. A finite element model was developed to optimize the geometry of the microchannel to achieve higher sensitivity. The highest gauge factor that was measured experimentally was 41. The gauge factor was affected by the microchannel’s square cross-sectional area, the number of basic units in the microchannel, and the inlet and outlet configuration. As a case study, the developed strain sensors were used to measure the rotation angle of the wrist and finger joints.

Direct Printing of a Flexible Strain Sensor for Distributed Monitoring of Deformation in Inflatable Structures

2019 ◽  
Author(s):  
Mohammed Al-Rubaiai ◽  
Ryohei Tsuruta ◽  
Taewoo Nam ◽  
Umesh Gandhi ◽  
Xiaobo Tan
Keyword(s):  
3D Printing ◽  
Structural Changes ◽  
Strain Sensor ◽  
Strain Range ◽  
Gauge Factor ◽  
Distributed Monitoring ◽  
Inflatable Structures ◽  
Resistance Change ◽  
Flexible Strain Sensor ◽  
Conductive Paint

Abstract Inflatable structures provide significant volume and weight savings for future space and soft robotic applications. Structural health monitoring (SHM) of these structures is essential to ensuring safe operation, providing early warnings of damage, and measuring structural changes over time. In this paper, we propose the design of a single flexible strain sensor for distributed monitoring of an inflatable tube, in particular, the detection and localization of a kink should that occur. Several commercially available conductive materials, including 3D-printing filaments, conductive paint, and conductive fabrics are explored for their strain-sensing performance, where the resistance change under uniaxial tension is measured, and the corresponding gauge factor (GF) is characterized. Flexible strain sensors are then fabricated and integrated with an inflatable structure fabric using screen-printing or 3D-printing techniques, depending on the nature of the raw conductive material. Among the tested materials, the conductive paint shows the highest stability, with GF of 15 and working strain range of 2.28%. Finally, the geometry of the sensor is designed to enable distributed monitoring of an inflatable tube. In particular, for a given deformation magnitude, the sensor output shows a monotonic relationship with the location where the deformation is applied, thus enabling the monitoring of the entire tube with a single sensor.

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