Stretchable and highly sensitive strain sensor based on conductive polymer aerogel for human physiological information detection

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.

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Largely Deformable and Highly Sensitive Strain Sensor Using Carbon Nanomaterials

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2017-70388 ◽

2017 ◽

Author(s):

Kanji Yumoto ◽

Ken Suzuki ◽

Hideo Miura

Keyword(s):

Aspect Ratio ◽

Growth Condition ◽

Electrical Resistance ◽

Carbon Nanomaterials ◽

Flexible Substrate ◽

Strain Sensor ◽

Sensitive Strain ◽

Synthesis Process ◽

Pressure Sensitivity ◽

Highly Sensitive

A new type tactile sensor with spatial resolution less than 1 mm and the minimum pressure sensitivity less than 10 kPa was proposed by applying MWCNTs (Multi-Walled Carbon Nanotubes). The sensor was embedded into a highly deformable flexible substrate (PDMS: Polydimethylsiloxane) and the obtained gauge factor of the developed sensor was about 5. Since the electronic properties of MWCNTs vary drastically depending on their deformation under mechanical stress, it is important to make appropriate aspect ratio of MWCNTs for improving their stress-sensitivity. The aspect ratio of MWCNTs are mainly dominated by their growth condition such as the average thickness of catalyst layer, growth temperature, pressure of resource gases and so on. Thus, the optimum growth condition was investigated for forming the MWCNTs with high aspect ratio, in other words, high pressure sensitivity. In addition, in this study, the authors fabricated high quality carbon nano-materials to develop highly sensitive strain sensor. A thermal CVD synthesis process of MWCNTs was developed by using acetylene gas. After the synthesis of MWCNTs, flexible isolation material (PDMS) was coated around the grown MWCNT. Then, the interconnection film was deposited by sputtering. After that, PDMS was coated again to fabricate an upper protection layer. Finally, the bottom interconnection layer was sputtered and patterned. The change of the electrical resistance of the grown MWCNTs was measured by applying a compression test in the load range from 0 to 10 mN. It was found that the electrical resistance of the MWCNTs bundle increased almost linearly with the applied compressive load and this sensor showed the high load sensitivity of 10 mN that is higher than human fingers.

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Highly sensitive strain sensor based on stretchable sandwich-type composite of carbon nanotube and poly(styrene–butadiene–styrene)

Sensors and Actuators A Physical ◽

10.1016/j.sna.2020.112357 ◽

2020 ◽

Vol 315 ◽

pp. 112357

Author(s):

Bing Qin ◽

Baobi Li ◽

Jie Zhang ◽

Xiaoling Xie ◽

Wei Li

Keyword(s):

Carbon Nanotube ◽

Strain Sensor ◽

Sensitive Strain ◽

Highly Sensitive ◽

Sandwich Type ◽

Styrene Butadiene Styrene ◽

Styrene Butadiene ◽

Type Composite ◽

Butadiene Styrene

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Highly Sensitive 2D Strain Sensor Using Carbon Nanotube

Volume 1: Advanced Packaging; Emerging Technologies; Modeling and Simulation; Multi-Physics Based Reliability; MEMS and NEMS; Materials and Processes ◽

10.1115/ipack2013-73156 ◽

2013 ◽

Author(s):

Hiroshi Kawakami ◽

Masato Ohnishi ◽

Ken Suzuki ◽

Hideo Miura

Keyword(s):

Carbon Nanotubes ◽

Compressive Strain ◽

Electronic Conductivity ◽

Strain Sensor ◽

Applied Strain ◽

Uniaxial Strain ◽

Sensitive Strain ◽

Highly Sensitive ◽

2D Strain ◽

Walled Carbon Nanotubes

A new highly sensitive strain measurement method has been developed by applying the strain-induced change of the electronic conductivity of CNTs. It is reported that most multi-walled carbon nanotubes (MWCNTs) show metallic conductivity and they are rather cheap comparing with single-walled carbon nanotubes (SWCNTs). However, it was found that the electric conductivity of MWCNTs changes drastically under uniaxial strain because of the drastic change of their band gap. Therefore, the authors have developed a highly sensitive strain sensor which can detect the local strain distribution by using MWCNTs. In order to design a new sensor using MWCNT, it is very important to control the shape of the MWCNTs under strain. Thus, a method for controlling the shape of the MWCNTs was developed by applying a chemical vapor deposition (CVD) technique. It was found that the shape of the grown MWCNT could be controlled by changing the average thickness of the catalyst and the deposition temperature of the MWCNT. The electrical resistance of the grown MWCNT changed almost linearly with the applied strain, and the maximum strain sensitivity obtained under the application of uniaxial strain was about 10%/1000-μstrain (gauge factor: 100). A two-dimensional strain sensor, which consists of area-arrayed fine bundles of MWCNTs, has been developed by applying MEMS technology. Under the application of compressive strain, the electric resistance was confirmed to increase almost linearly with the applied strain.

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