A direction-aware and ultrafast self-healing dual network hydrogel for a flexible electronic skin strain sensor

Flexible elastomer material with high stretchability and self-healing performance is the preferred substrates for preparing multi-function flexible sensors and bionic electronic skin. However, it is still a great challenge to...

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A Versatile Wax Assisted Double Replica Molding and its Application in Flexible Electronic Skin

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2021.130132 ◽

2021 ◽

pp. 130132

Author(s):

Huihui Chai ◽

Feng Chen ◽

Zhaoxi Song ◽

Lulu Xiong ◽

Gang Xiao ◽

...

Keyword(s):

Replica Molding ◽

Electronic Skin ◽

Flexible Electronic

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Dynamic Nanohybrid-Polysaccharide Hydrogels for Soft Wearable Strain Sensing

Sensors ◽

10.3390/s21113574 ◽

2021 ◽

Vol 21 (11) ◽

pp. 3574

Author(s):

Pejman Heidarian ◽

Hossein Yousefi ◽

Akif Kaynak ◽

Mariana Paulino ◽

Saleh Gharaie ◽

...

Keyword(s):

Mechanical Strength ◽

Strain Sensors ◽

Self Healing ◽

Nano Materials ◽

Strain Sensing ◽

Ferric Ions ◽

Research Activity ◽

Adhesion Properties ◽

High Mechanical Strength ◽

The Moment

Electroconductive hydrogels with stimuli-free self-healing and self-recovery (SELF) properties and high mechanical strength for wearable strain sensors is an area of intensive research activity at the moment. Most electroconductive hydrogels, however, consist of static bonds for mechanical strength and dynamic bonds for SELF performance, presenting a challenge to improve both properties into one single hydrogel. An alternative strategy to successfully incorporate both properties into one system is via the use of stiff or rigid, yet dynamic nano-materials. In this work, a nano-hybrid modifier derived from nano-chitin coated with ferric ions and tannic acid (TA/Fe@ChNFs) is blended into a starch/polyvinyl alcohol/polyacrylic acid (St/PVA/PAA) hydrogel. It is hypothesized that the TA/Fe@ChNFs nanohybrid imparts both mechanical strength and stimuli-free SELF properties to the hydrogel via dynamic catecholato-metal coordination bonds. Additionally, the catechol groups of TA provide mussel-inspired adhesion properties to the hydrogel. Due to its electroconductivity, toughness, stimuli-free SELF properties, and self-adhesiveness, a prototype soft wearable strain sensor is created using this hydrogel and subsequently tested.

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

Nanomaterials ◽

10.3390/nano11071701 ◽

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.

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Strain Sensor Based on Biological Nanomaterial

Engineering Proceedings ◽

10.3390/i3s2021dresden-10115 ◽

2021 ◽

Vol 6 (1) ◽

pp. 23

Author(s):

Levan P. Ichkitidze ◽

Alexander Yu. Gerasimenko ◽

Dmitry V. Telyshev ◽

Eugeny P. Kitsyuk ◽

Vladimir A. Petukhov ◽

...

Keyword(s):

Screen Printing ◽

Respiratory Diseases ◽

Specific Conductivity ◽

Strain Sensor ◽

Aqueous Dispersion ◽

Strain Sensors ◽

Bending Angle ◽

Multi Walled Carbon Nanotubes ◽

Number Of Cycles ◽

Walled Carbon Nanotubes

We investigated a prototype of a strain sensor based on the layers of a bionanomaterial containing bovine serum albumin (BSA matrix) and multi-walled carbon nanotubes (MWCNT filler). The aqueous dispersion of 25 wt.% BSA/0.3 wt.% MWCNT was applied by screen printing onto flexible polyethylene terephthalate substrates. After drying the layers by laser irradiation (~970 nm), various parameters of the layers were controlled, i.e., resistance R, bending angle θ, number of cycles n, and measurement time. One measurement cycle corresponded to a change within the range θ = ±150°. The layers of the BSA/MWCNT bionanomaterial had dimensions of (15 ÷ 20) mm × (8 ÷ 10) mm × (0.5 ÷ 1. 5) µm. The dependences of resistance R on the bending angle θ were similar for all layers at θ = ±30, and the R(θ) curves represented approximate linear dependences (with an error of ≤ 10%); beyond this range, the dependences became nonlinear. The following quantitative values were obtained for the investigated strain sensor: specific conductivity ~1 ÷ 10 S/m, linear strain sensitivity ~160, and bending sensitivity 1.0 ÷ 1.5%/°. These results are high. The examined layers of the bionanomaterial BSA/MWCNT as a strain sensor are of particular interest for medical practice. In particular, strain sensors can be implemented by applying a water dispersion of nanomaterials to human skin using a 3D printer for monitoring movements (arms and blinking) and the detection of signs of pathology (dysphagia, respiratory diseases, angina, etc.).

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Polar poly(n-butyl acrylate)-g-polyacrylonitrile elastomer with high temperature elasticity and healability as flexible electronic substrate

Fashion and Textiles ◽

10.1186/s40691-020-00235-4 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Yuzhu Zheng ◽

Deli Xu ◽

Shiyou Tian ◽

Manli Li ◽

Wenwen Wang ◽

...

Keyword(s):

High Temperature ◽

Graft Copolymer ◽

Butyl Acrylate ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Self Healing ◽

Chemical Structures ◽

Flexible Electronic ◽

Ag Nanowires ◽

Cyano Groups

AbstractIn this work, graft copolymer poly (n-butyl acrylate)-g-polyacrylonitrile with poly (n-butyl acrylate) as backbones and polyacrylonitrile as side chains (PnBA-g-PAN) was synthesized by macromonomer method and emulsion polymerization. The macromonomer was synthesized by atom transfer radical polymerization and end-group modification. The chemical structures and thermal properties of macromonomer and graft copolymer were investigated by FTIR, GPC, NMR and TGA, etc. The mechanical properties of graft copolymer elastomer was also measured by uniaxial tensile test. Rheological properties at different temperature and mechanical property demonstrated that graft copolymer elastomer possessed elasticity until 180 oC because of cyclization of cyano groups. Ag nanowires@PnBA-g-PAN composite elastomer was developed, and the resulted material exhibited autonomic healing property on account of segments’ flexibility and dynamic interaction between Ag nanowires (AgNWs) and cyano groups. This is a general method for generation of elastomer with high temperature elasticity and fast self-healing. The composite elastomer has potential application in flexible electronic conductor.

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

Materials ◽

10.3390/ma12091469 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1469 ◽

Cited By ~ 10

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.

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Structural Reinforcement Effect of a Flexible Strain Sensor Integrated with Pneumatic Balloon Actuators for Soft Microrobot Fingers

Micromachines ◽

10.3390/mi12040395 ◽

2021 ◽

Vol 12 (4) ◽

pp. 395

Author(s):

Satoshi Konishi ◽

Fuminari Mori ◽

Ayano Shimizu ◽

Akiya Hirata

Keyword(s):

Liquid Metal ◽

Strain Sensor ◽

Strain Sensors ◽

Original Performance ◽

Sensors And Actuators ◽

Parylene C ◽

Structural Reinforcement ◽

Effective Combination ◽

Metal Strain ◽

Flexible Strain Sensor

Motion capture of a robot and tactile sensing for a robot require sensors. Strain sensors are used to detect bending deformation of the robot finger and to sense the force from an object. It is important to introduce sensors in effective combination with actuators without affecting the original performance of the robot. We are interested in the improvement of flexible strain sensors integrated into soft microrobot fingers using a pneumatic balloon actuator (PBA). A strain sensor using a microchannel filled with liquid metal was developed for soft PBAs by considering the compatibility of sensors and actuators. Inflatable deformation generated by PBAs, however, was found to affect sensor characteristics. This paper presents structural reinforcement of a liquid metal-based sensor to solve this problem. Parylene C film was deposited into a microchannel to reinforce its structure against the inflatable deformation caused by a PBA. Parylene C deposition into a microchannel suppressed the interference of inflatable deformation. The proposed method enables the effective combination of soft PBAs and a flexible liquid metal strain sensor for use in microrobot fingers.

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