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Dr. Morteza Amjadi
Institute of Mechanical, Process and Energy Engineering, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom

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0 Composite materials
0 soft robotics
0 soft actuators
0 Functional nanomaterials
0 soft sensors

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soft robotics
soft actuators
Functional nanomaterials
soft sensors

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Review
Published: 11 June 2020 in Advanced Intelligent Systems
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Recent advances in the design and implementation of wearable resistive, capacitive, and optical strain sensors are summarized herein. Wearable and stretchable strain sensors have received extensive research interest due to their applications in personalized healthcare, human motion detection, human–machine interfaces, soft robotics, and beyond. The disconnection of overlapped nanomaterials, reversible opening/closing of microcracks in sensing films, and alteration of the tunneling resistance have been successfully adopted to develop high‐performance resistive‐type sensors. On the other hand, the sensing behavior of capacitive‐type and optical strain sensors is largely governed by their geometrical changes under stretching/releasing cycles. The sensor design parameters, including stretchability, sensitivity, linearity, hysteresis, and dynamic durability, are comprehensively discussed. Finally, the promising applications of wearable strain sensors are highlighted in detail. Although considerable progress has been made so far, wearable strain sensors are still in their prototype stage, and several challenges in the manufacturing of integrated and multifunctional strain sensors should be yet tackled.

ACS Style

Hamid Souri; Hritwick Banerjee; Ardian Jusufi; Norbert Radacsi; Adam A. Stokes; Inkyu Park; Metin Sitti; Morteza Amjadi. Wearable and Stretchable Strain Sensors: Materials, Sensing Mechanisms, and Applications. Advanced Intelligent Systems 2020, 2, 1 .

AMA Style

Hamid Souri, Hritwick Banerjee, Ardian Jusufi, Norbert Radacsi, Adam A. Stokes, Inkyu Park, Metin Sitti, Morteza Amjadi. Wearable and Stretchable Strain Sensors: Materials, Sensing Mechanisms, and Applications. Advanced Intelligent Systems. 2020; 2 (8):1.

Chicago/Turabian Style

Hamid Souri; Hritwick Banerjee; Ardian Jusufi; Norbert Radacsi; Adam A. Stokes; Inkyu Park; Metin Sitti; Morteza Amjadi. 2020. "Wearable and Stretchable Strain Sensors: Materials, Sensing Mechanisms, and Applications." Advanced Intelligent Systems 2, no. 8: 1.

Paper
Published: 20 March 2020 in Journal of Materials Chemistry C
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The impact of environmental parameters on the sensing behavior of carbon nanotube–elastomer nanocomposite strain sensors has been investigated, revealing significant effect of temperature and humidity variations on the sensing performance.

ACS Style

Mohammad Nankali; Nowrouz Mohammad Nouri; Mahdi Navidbakhsh; Nima Geran Malek; Mohammad Amin Amindehghan; Abdolsamad Montazeri Shahtoori; Marita Karimi; Morteza Amjadi. Highly stretchable and sensitive strain sensors based on carbon nanotube–elastomer nanocomposites: the effect of environmental factors on strain sensing performance. Journal of Materials Chemistry C 2020, 8, 6185 -6195.

AMA Style

Mohammad Nankali, Nowrouz Mohammad Nouri, Mahdi Navidbakhsh, Nima Geran Malek, Mohammad Amin Amindehghan, Abdolsamad Montazeri Shahtoori, Marita Karimi, Morteza Amjadi. Highly stretchable and sensitive strain sensors based on carbon nanotube–elastomer nanocomposites: the effect of environmental factors on strain sensing performance. Journal of Materials Chemistry C. 2020; 8 (18):6185-6195.

Chicago/Turabian Style

Mohammad Nankali; Nowrouz Mohammad Nouri; Mahdi Navidbakhsh; Nima Geran Malek; Mohammad Amin Amindehghan; Abdolsamad Montazeri Shahtoori; Marita Karimi; Morteza Amjadi. 2020. "Highly stretchable and sensitive strain sensors based on carbon nanotube–elastomer nanocomposites: the effect of environmental factors on strain sensing performance." Journal of Materials Chemistry C 8, no. 18: 6185-6195.

Journal article
Published: 05 June 2019 in ACS Applied Materials & Interfaces
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Flexible and wearable pressure sensors have attracted a tremendous amount of attention due to their wider applications in human interfaces and healthcare monitoring. However, achieving accurate pressure detection and stability against external stimuli (in particular, bending deformation) over a wide range of pressures from tactile to body weight levels is a great challenge. Here, we introduce an ultrawide-range, bending-insensitive, and flexible pressure sensor based on a carbon nanotube (CNT) network-coated thin porous elastomer sponge for use in human interface devices. The integration of the CNT networks into three-dimensional microporous elastomers provides high deformability and a large change in contact between the conductive CNT networks due to the presence of micropores, thereby improving the sensitivity compared with that obtained using CNT-embedded solid elastomers. As electrical pathways are continuously generated up to high compressive strain (∼80%), the pressure sensor shows an ultrawide pressure sensing range (10 Pa to 1.2 MPa) while maintaining favorable sensitivity (0.01-0.02 kPa-1) and linearity ( R2 ∼ 0.98). Also, the pressure sensor exhibits excellent electromechanical stability and insensitivity to bending-induced deformations. Finally, we demonstrate that the pressure sensor can be applied in a flexible piano pad as an entertainment human interface device and a flexible foot insole as a wearable healthcare and gait monitoring device.

ACS Style

Seunghwan Kim; Morteza Amjadi; Tae-Ik Lee; Yongrok Jeong; Donguk Kwon; Min Seong Kim; Kyuyoung Kim; Taek-Soo Kim; Yong Suk Oh; Inkyu Park. Wearable, Ultrawide-Range, and Bending-Insensitive Pressure Sensor Based on Carbon Nanotube Network-Coated Porous Elastomer Sponges for Human Interface and Healthcare Devices. ACS Applied Materials & Interfaces 2019, 11, 23639 -23648.

AMA Style

Seunghwan Kim, Morteza Amjadi, Tae-Ik Lee, Yongrok Jeong, Donguk Kwon, Min Seong Kim, Kyuyoung Kim, Taek-Soo Kim, Yong Suk Oh, Inkyu Park. Wearable, Ultrawide-Range, and Bending-Insensitive Pressure Sensor Based on Carbon Nanotube Network-Coated Porous Elastomer Sponges for Human Interface and Healthcare Devices. ACS Applied Materials & Interfaces. 2019; 11 (26):23639-23648.

Chicago/Turabian Style

Seunghwan Kim; Morteza Amjadi; Tae-Ik Lee; Yongrok Jeong; Donguk Kwon; Min Seong Kim; Kyuyoung Kim; Taek-Soo Kim; Yong Suk Oh; Inkyu Park. 2019. "Wearable, Ultrawide-Range, and Bending-Insensitive Pressure Sensor Based on Carbon Nanotube Network-Coated Porous Elastomer Sponges for Human Interface and Healthcare Devices." ACS Applied Materials & Interfaces 11, no. 26: 23639-23648.

Communication
Published: 16 May 2018 in Advanced Science
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Soft actuators have demonstrated potential in a range of applications, including soft robotics, artificial muscles, and biomimetic devices. However, the majority of current soft actuators suffer from the lack of real‐time sensory feedback, prohibiting their effective sensing and multitask function. Here, a promising strategy is reported to design bilayer electrothermal actuators capable of simultaneous actuation and sensation (i.e., self‐sensing actuators), merely through two input electric terminals. Decoupled electrothermal stimulation and strain sensation is achieved by the optimal combination of graphite microparticles and carbon nanotubes (CNTs) in the form of hybrid films. By finely tuning the charge transport properties of hybrid films, the signal‐to‐noise ratio (SNR) of self‐sensing actuators is remarkably enhanced to over 66. As a result, self‐sensing actuators can actively track their displacement and distinguish the touch of soft and hard objects.

ACS Style

Morteza Amjadi; Metin Sitti. Self-Sensing Paper Actuators Based on Graphite-Carbon Nanotube Hybrid Films. Advanced Science 2018, 5, 1800239 .

AMA Style

Morteza Amjadi, Metin Sitti. Self-Sensing Paper Actuators Based on Graphite-Carbon Nanotube Hybrid Films. Advanced Science. 2018; 5 (7):1800239.

Chicago/Turabian Style

Morteza Amjadi; Metin Sitti. 2018. "Self-Sensing Paper Actuators Based on Graphite-Carbon Nanotube Hybrid Films." Advanced Science 5, no. 7: 1800239.

Progress report
Published: 08 January 2018 in Advanced Materials
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Wearable transdermal delivery systems have recently received tremendous attention due to their noninvasive, convenient, and prolonged administration of pharmacological agents. Here, the material prospects, fabrication processes, and drug‐release mechanisms of these types of therapeutic delivery systems are critically reviewed. The latest progress in the development of multifunctional wearable devices capable of closed‐loop sensation and drug delivery is also discussed. This survey reveals that wearable transdermal delivery has already made an impact in diverse healthcare applications, while several grand challenges remain.

ACS Style

Morteza Amjadi; Sahar Sheykhansari; Bradley J. Nelson; Metin Sitti. Recent Advances in Wearable Transdermal Delivery Systems. Advanced Materials 2018, 30, 1 .

AMA Style

Morteza Amjadi, Sahar Sheykhansari, Bradley J. Nelson, Metin Sitti. Recent Advances in Wearable Transdermal Delivery Systems. Advanced Materials. 2018; 30 (7):1.

Chicago/Turabian Style

Morteza Amjadi; Sahar Sheykhansari; Bradley J. Nelson; Metin Sitti. 2018. "Recent Advances in Wearable Transdermal Delivery Systems." Advanced Materials 30, no. 7: 1.

Article
Published: 21 July 2017 in Advanced Materials
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In article number 1701353, Metin Sitti and co-workers develop bioinspired skin-adhesives composed of microfibrills decorated with conformal and mushroom-shaped tips for strong attachment to dry and wet skin. A high skin-adhesion strength of 18 kPa, along with highly enhanced signal-to-noise quality of integrated wearable strain sensors are achieved by excellent shape adaptation and microfibrillar design of skin-adhesive films.

ACS Style

Dirk-M. Drotlef; Morteza Amjadi; Muhammad Yunusa; Metin Sitti. Microfibers: Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors (Adv. Mater. 28/2017). Advanced Materials 2017, 29, 1 .

AMA Style

Dirk-M. Drotlef, Morteza Amjadi, Muhammad Yunusa, Metin Sitti. Microfibers: Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors (Adv. Mater. 28/2017). Advanced Materials. 2017; 29 (28):1.

Chicago/Turabian Style

Dirk-M. Drotlef; Morteza Amjadi; Muhammad Yunusa; Metin Sitti. 2017. "Microfibers: Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors (Adv. Mater. 28/2017)." Advanced Materials 29, no. 28: 1.

Review
Published: 13 July 2017 in Current Gene Therapy
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There is a growing interest in transdermal delivery systems because of their noninvasive, targeted, and on-demand delivery of gene and drugs. However, efficient penetration of therapeutic compounds into the skin is still challenging largely due to the impermeability of the outermost layer of the skin, known as stratum corneum. Recently, there have been major research activities to enhance the skin penetration depth of pharmacological agents. This article reviews recent advances in the development of various strategies for skin penetration enhancement. We show that approaches such as ultrasound waves, laser, and microneedle patches have successfully been employed to physically disrupt the stratum corneum structure for enhanced transdermal delivery. Rather than physical approaches, several non-physical route have also been utilized for efficient transdermal delivery across the skin barrier. Finally, we discuss some clinical applications of transdermal delivery systems for gene and drug delivery. This paper shows that transdermal delivery devices can potentially function for diverse healthcare and medical applications while further investigations are still necessary for more efficient skin penetration of gene and drugs.

ACS Style

Morteza Amjadi; Babak Mostaghaci; Metin Sitti. Recent Advances in Skin Penetration Enhancers for Transdermal Gene and Drug Delivery. Current Gene Therapy 2017, 17, 139 -146.

AMA Style

Morteza Amjadi, Babak Mostaghaci, Metin Sitti. Recent Advances in Skin Penetration Enhancers for Transdermal Gene and Drug Delivery. Current Gene Therapy. 2017; 17 (2):139-146.

Chicago/Turabian Style

Morteza Amjadi; Babak Mostaghaci; Metin Sitti. 2017. "Recent Advances in Skin Penetration Enhancers for Transdermal Gene and Drug Delivery." Current Gene Therapy 17, no. 2: 139-146.

Article
Published: 19 May 2017 in Advanced Materials
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A facile approach is proposed for superior conformation and adhesion of wearable sensors to dry and wet skin. Bioinspired skin-adhesive films are composed of elastomeric microfibers decorated with conformal and mushroom-shaped vinylsiloxane tips. Strong skin adhesion is achieved by crosslinking the viscous vinylsiloxane tips directly on the skin surface. Furthermore, composite microfibrillar adhesive films possess a high adhesion strength of 18 kPa due to the excellent shape adaptation of the vinylsiloxane tips to the multiscale roughness of the skin. As a utility of the skin-adhesive films in wearable-device applications, they are integrated with wearable strain sensors for respiratory and heart-rate monitoring. The signal-to-noise ratio of the strain sensor is significantly improved to 59.7 because of the considerable signal amplification of microfibrillar skin-adhesive films.

ACS Style

Dirk-M. Drotlef; Morteza Amjadi; Muhammad Yunusa; Metin Sitti. Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors. Advanced Materials 2017, 29, 1 .

AMA Style

Dirk-M. Drotlef, Morteza Amjadi, Muhammad Yunusa, Metin Sitti. Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors. Advanced Materials. 2017; 29 (28):1.

Chicago/Turabian Style

Dirk-M. Drotlef; Morteza Amjadi; Muhammad Yunusa; Metin Sitti. 2017. "Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors." Advanced Materials 29, no. 28: 1.

Research article
Published: 18 October 2016 in ACS Nano
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There is an increasing demand for soft actuators because of their importance in soft robotics, artificial muscles, biomimetic devices, and beyond. However, the development of soft actuators capable of low-voltage operation, powerful actuation, and programmable shape-changing is still challenging. In this work, we propose programmable bilayer actuators that operate based on the large hygroscopic contraction of the copy paper and simultaneously large thermal expansion of the polypropylene film upon increasing the temperature. The electrothermally activated bending actuators can function with low voltages (≤ 8 V), low input electric power per area (P ≤ 0.14 W cm–2), and low temperature changes (≤ 35 °C). They exhibit reversible shape-changing behavior with curvature radii up to 1.07 cm–1 and bending angle of 360°, accompanied by powerful actuation. Besides the electrical activation, they can be powered by humidity or light irradiation. We finally demonstrate the use of our paper actuators as a soft gripper robot and a lightweight paper wing for aerial robotics.

ACS Style

Morteza Amjadi; Metin Sitti. High-Performance Multiresponsive Paper Actuators. ACS Nano 2016, 10, 10202 -10210.

AMA Style

Morteza Amjadi, Metin Sitti. High-Performance Multiresponsive Paper Actuators. ACS Nano. 2016; 10 (11):10202-10210.

Chicago/Turabian Style

Morteza Amjadi; Metin Sitti. 2016. "High-Performance Multiresponsive Paper Actuators." ACS Nano 10, no. 11: 10202-10210.

Article
Published: 31 August 2016 in Physical Review Applied
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Coupling mechanical degrees of freedom to single well-controlled quantum systems has become subject to intense research recently. Here, we report on the design, fabrication, and characterization of a diamond architecture consisting of a high-quality thin circular diamond membrane with embedded near-surface nitrogen-vacancy centers (NVCs). To demonstrate this architecture, we employ the NVCs by means of their optical and spin interfaces as nanosensors of the motion of the membrane under static pressure and in-resonance vibration. We also monitor the static residual stress within the membrane using the same method. Driving the membrane at its fundamental resonance mode, we observe coupling of this vibrational mode to the spin of the NVCs. Our realization of this architecture can manifest the applications of diamond structures in 3D piezometry such as mechanobiology and vibrometry, as well as mechanically mediated spin-spin coupling in quantum-information science.

ACS Style

S. Ali Momenzadeh; Felipe Fávaro De Oliveira; Philipp Neumann; D. D. Bhaktavatsala Rao; Andrej Denisenko; Morteza Amjadi; Zhiqin Chu; Sen Yang; Neil B. Manson; Marcus W. Doherty; Jörg Wrachtrup. Thin Circular Diamond Membrane with Embedded Nitrogen-Vacancy Centers for Hybrid Spin-Mechanical Quantum Systems. Physical Review Applied 2016, 6, 024026 .

AMA Style

S. Ali Momenzadeh, Felipe Fávaro De Oliveira, Philipp Neumann, D. D. Bhaktavatsala Rao, Andrej Denisenko, Morteza Amjadi, Zhiqin Chu, Sen Yang, Neil B. Manson, Marcus W. Doherty, Jörg Wrachtrup. Thin Circular Diamond Membrane with Embedded Nitrogen-Vacancy Centers for Hybrid Spin-Mechanical Quantum Systems. Physical Review Applied. 2016; 6 (2):024026.

Chicago/Turabian Style

S. Ali Momenzadeh; Felipe Fávaro De Oliveira; Philipp Neumann; D. D. Bhaktavatsala Rao; Andrej Denisenko; Morteza Amjadi; Zhiqin Chu; Sen Yang; Neil B. Manson; Marcus W. Doherty; Jörg Wrachtrup. 2016. "Thin Circular Diamond Membrane with Embedded Nitrogen-Vacancy Centers for Hybrid Spin-Mechanical Quantum Systems." Physical Review Applied 6, no. 2: 024026.

Review
Published: 17 February 2016 in Advanced Functional Materials
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There is a growing demand for flexible and soft electronic devices. In particular, stretchable, skin-mountable, and wearable strain sensors are needed for several potential applications including personalized health-monitoring, human motion detection, human-machine interfaces, soft robotics, and so forth. This Feature Article presents recent advancements in the development of flexible and stretchable strain sensors. The article shows that highly stretchable strain sensors are successfully being developed by new mechanisms such as disconnection between overlapped nanomaterials, crack propagation in thin films, and tunneling effect, different from traditional strain sensing mechanisms. Strain sensing performances of recently reported strain sensors are comprehensively studied and discussed, showing that appropriate choice of composite structures as well as suitable interaction between functional nanomaterials and polymers are essential for the high performance strain sensing. Next, simulation results of piezoresistivity of stretchable strain sensors by computational models are reported. Finally, potential applications of flexible strain sensors are described. This survey reveals that flexible, skin-mountable, and wearable strain sensors have potential in diverse applications while several grand challenges have to be still overcome.

ACS Style

Morteza Amjadi; Ki-Uk Kyung; Inkyu Park; Metin Sitti. Stretchable, Skin-Mountable, and Wearable Strain Sensors and Their Potential Applications: A Review. Advanced Functional Materials 2016, 26, 1678 -1698.

AMA Style

Morteza Amjadi, Ki-Uk Kyung, Inkyu Park, Metin Sitti. Stretchable, Skin-Mountable, and Wearable Strain Sensors and Their Potential Applications: A Review. Advanced Functional Materials. 2016; 26 (11):1678-1698.

Chicago/Turabian Style

Morteza Amjadi; Ki-Uk Kyung; Inkyu Park; Metin Sitti. 2016. "Stretchable, Skin-Mountable, and Wearable Strain Sensors and Their Potential Applications: A Review." Advanced Functional Materials 26, no. 11: 1678-1698.

Research article
Published: 16 February 2016 in ACS Applied Materials & Interfaces
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There is an increasing demand for flexible, skin-attachable, and wearable strain sensors due to their various potential applications. However, achieving strain sensors with both high sensitivity and high stretchability is still a grand challenge. Here, we propose highly sensitive and stretchable strain sensors based on the reversible microcrack formation in composite thin films. Controllable parallel microcracks are generated in graphite thin films coated on elastomer films. Sensors made of graphite thin films with short microcracks possess high gauge factors (maximum value of 522.6) and stretchability (ε ≥ 50%), whereas sensors with long microcracks show ultrahigh sensitivity (maximum value of 11 344) with limited stretchability (ε ≤ 50%). We demonstrate the high performance strain sensing of our sensors in both small and large strain sensing applications such as human physiological activity recognition, human body large motion capturing, vibration detection, pressure sensing, and soft robotics.

ACS Style

Morteza Amjadi; Mehmet Turan; Cameron P. Clementson; Metin Sitti. Parallel Microcracks-based Ultrasensitive and Highly Stretchable Strain Sensors. ACS Applied Materials & Interfaces 2016, 8, 5618 -5626.

AMA Style

Morteza Amjadi, Mehmet Turan, Cameron P. Clementson, Metin Sitti. Parallel Microcracks-based Ultrasensitive and Highly Stretchable Strain Sensors. ACS Applied Materials & Interfaces. 2016; 8 (8):5618-5626.

Chicago/Turabian Style

Morteza Amjadi; Mehmet Turan; Cameron P. Clementson; Metin Sitti. 2016. "Parallel Microcracks-based Ultrasensitive and Highly Stretchable Strain Sensors." ACS Applied Materials & Interfaces 8, no. 8: 5618-5626.

Conference paper
Published: 01 November 2015 in 2015 IEEE SENSORS
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Finger motion capturing systems have a wide variety of applications such as telerobotics, rehabilitation, and avatar control. While commercial devices are too costly, studies on such systems are either impractical to use or have speed limitations. This paper proposes a practical version of the glove-based finger motion capturing system. This system can achieve a capture speed high enough to represent smooth and swift finger motions with considerably low cost. The system provides a speed of 54 Hz for 14 channels with their signal conditioning circuits and flexible strain sensors. In addition, the system has one-touch calibration mode for baseline cancellation, which makes it user-friendly more.

ACS Style

Ji-Hoon Suh; Morteza Amjadi; Inkyu Park; Hyung-Joun Yoo. Finger motion detection glove toward human-machine interface. 2015 IEEE SENSORS 2015, 1 -4.

AMA Style

Ji-Hoon Suh, Morteza Amjadi, Inkyu Park, Hyung-Joun Yoo. Finger motion detection glove toward human-machine interface. 2015 IEEE SENSORS. 2015; ():1-4.

Chicago/Turabian Style

Ji-Hoon Suh; Morteza Amjadi; Inkyu Park; Hyung-Joun Yoo. 2015. "Finger motion detection glove toward human-machine interface." 2015 IEEE SENSORS , no. : 1-4.

Text
Published: 01 November 2015 in AIP Advances
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Possessing a strong piezoresistivity,nanocomposites of metal nanowires and elastomer have been studied extensively for its use in highly flexible, stretchable, and sensitive sensors. In this work, we analyze the working mechanism and performance of a nanocomposite based stretchable strain sensor by calculating the conductivity of the nanowirepercolationnetwork as a function of strain. We reveal that the nonlinear piezoresistivity is attributed to the topological change of percolationnetwork, which leads to a bottleneck in the electric path. We find that, due to enhanced percolation, the linearity of the sensor improves with increasing aspect ratio or volume fraction of the nanowires at the expense of decreasing gauge factor. In addition, we show that a wide range of gauge factors (from negative to positive) can be obtained by changing the orientation distribution of nanowires. Our study suggests a way to intelligently design nanocomposite-based piezoresistivesensors for flexible and wearable devices.

ACS Style

Sangryun Lee; Morteza Amjadi; Nicola Pugno; Inkyu Park; Seunghwa Ryu. Computational analysis of metallic nanowire-elastomer nanocomposite based strain sensors. AIP Advances 2015, 5, 117233 .

AMA Style

Sangryun Lee, Morteza Amjadi, Nicola Pugno, Inkyu Park, Seunghwa Ryu. Computational analysis of metallic nanowire-elastomer nanocomposite based strain sensors. AIP Advances. 2015; 5 (11):117233.

Chicago/Turabian Style

Sangryun Lee; Morteza Amjadi; Nicola Pugno; Inkyu Park; Seunghwa Ryu. 2015. "Computational analysis of metallic nanowire-elastomer nanocomposite based strain sensors." AIP Advances 5, no. 11: 117233.

Journal article
Published: 25 August 2015 in Nanotechnology
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Super-stretchable, skin-mountable, and ultra-soft strain sensors are presented by using carbon nanotube percolation network-silicone rubber nanocomposite thin films. The applicability of the strain sensors as epidermal electronic systems, in which mechanical compliance like human skin and high stretchability (ϵ > 100%) are required, has been explored. The sensitivity of the strain sensors can be tuned by the number density of the carbon nanotube percolation network. The strain sensors show excellent hysteresis performance at different strain levels and rates with high linearity and small drift. We found that the carbon nanotube-silicone rubber based strain sensors possess super-stretchability and high reliability for strains as large as 500%. The nanocomposite thin films exhibit high robustness and excellent resistance-strain dependency for over ~1380% mechanical strain. Finally, we performed skin motion detection by mounting the strain sensors on different parts of the body. The maximum induced strain by the bending of the finger, wrist, and elbow was measured to be ~ 42%, 45% and 63%, respectively.

ACS Style

Morteza Amjadi; Yong Jin Yoon; Inkyu Park. Ultra-stretchable and skin-mountable strain sensors using carbon nanotubes–Ecoflex nanocomposites. Nanotechnology 2015, 26, 375501 .

AMA Style

Morteza Amjadi, Yong Jin Yoon, Inkyu Park. Ultra-stretchable and skin-mountable strain sensors using carbon nanotubes–Ecoflex nanocomposites. Nanotechnology. 2015; 26 (37):375501.

Chicago/Turabian Style

Morteza Amjadi; Yong Jin Yoon; Inkyu Park. 2015. "Ultra-stretchable and skin-mountable strain sensors using carbon nanotubes–Ecoflex nanocomposites." Nanotechnology 26, no. 37: 375501.

Conference paper
Published: 01 January 2015 in 2015 28th IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
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We developed highly stretchable, flexible and very soft conductors based on the carbon nanotubes (CNTs)-silicone rubber (Ecoflex®) nanocomposite thin films. The resistance of the CNTs-Ecoflex nanocomposite thin film was recovered to its original value under cyclic loading/unloading for strains as large as 510%. Failure strain of the CNTs-Ecoflex nanocomposite was measured to be about ~ 1380% showing its ultra-high stretchability and robustness. As an application of our highly stretchable conductors, we utilized them as skin-mountable and wearable strain sensors for human motion detection. The strain sensors possess high linearity and low hysteresis performance. We observed overshoot behavior of the strain sensors with maximum normalized overshooting peaks 15%. Finally, motion detection of the finger and wrist joints was conducted by using CNTs-Ecoflex nanocomposite thin film strain sensors.

ACS Style

Morteza Amjadi; Inkyu Park. Carbon nanotubes-ecoflex nanocomposite for strain sensing with ultra-high stretchability. 2015 28th IEEE International Conference on Micro Electro Mechanical Systems (MEMS) 2015, 744 -747.

AMA Style

Morteza Amjadi, Inkyu Park. Carbon nanotubes-ecoflex nanocomposite for strain sensing with ultra-high stretchability. 2015 28th IEEE International Conference on Micro Electro Mechanical Systems (MEMS). 2015; ():744-747.

Chicago/Turabian Style

Morteza Amjadi; Inkyu Park. 2015. "Carbon nanotubes-ecoflex nanocomposite for strain sensing with ultra-high stretchability." 2015 28th IEEE International Conference on Micro Electro Mechanical Systems (MEMS) , no. : 744-747.

Conference paper
Published: 01 August 2014 in 14th IEEE International Conference on Nanotechnology
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We develop highly flexible and compressible 3D interconnected porous PDMS structures by using sugar cubes as templates. The porous structures can be compressed to more than 80% without any side-wall buckling comparable with bulk polymers. Force sensitive resistors were fabricated by filtration of the CNT solution inside the porous structure of PDMS. We found that sufficient acid treatment can increase the adhesion and bonding between CNTs and PDMS. Force sensitive resistors respond the applied pressure and compressive strains by high linearity (R2>0.97) and sensitivity (GFs>2) with a reliable manner. Finally, as an application of our force sensitive resistors, a flexible foot pad containing force sensitive resistors arrays is developed for the foot sole distributed force detection.

ACS Style

Morteza Amjadi; Min Seong Kim; Inkyu Park. Flexible and sensitive foot pad for sole distributed force detection. 14th IEEE International Conference on Nanotechnology 2014, 764 -767.

AMA Style

Morteza Amjadi, Min Seong Kim, Inkyu Park. Flexible and sensitive foot pad for sole distributed force detection. 14th IEEE International Conference on Nanotechnology. 2014; ():764-767.

Chicago/Turabian Style

Morteza Amjadi; Min Seong Kim; Inkyu Park. 2014. "Flexible and sensitive foot pad for sole distributed force detection." 14th IEEE International Conference on Nanotechnology , no. : 764-767.

Journal article
Published: 24 June 2014 in Small
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Silver nanowire (Ag NW) based transparent electrodes are inherently unstable to moist and chemically reactive environment. A remarkable stability improvement of the Ag NW network film against oxidizing and sulfurizing environment by local electrodeposition of Ni along Ag NWs is reported. The optical transmittance and electrical resistance of the Ni deposited Ag NW network film can be easily controlled by adjusting the morphology and thickness of the Ni shell layer. The electrical conductivity of the Ag NW network film is increased by the Ni coating via welding between Ag NWs as well as additional conductive area for the electron transport by electrodeposited Ni layer. Moreover, the chemical resistance of Ag NWs against oxidation and sulfurization can be dramatically enhanced by the Ni shell layer electrodeposited along the Ag NWs, which provides the physical barrier against chemical reaction and diffusion as well as the cathodic protection from galvanic corrosion.

ACS Style

Hyeonjin Eom; Jaemin Lee; Aekachan Pichitpajongkit; Morteza Amjadi; Jun-Ho Jeong; Eungsug Lee; Jung-Yong Lee; Inkyu Park. [email protected] Core-Shell Nanowire Network for Robust Transparent Electrodes Against Oxidation and Sulfurization. Small 2014, 10, 4171 -4181.

AMA Style

Hyeonjin Eom, Jaemin Lee, Aekachan Pichitpajongkit, Morteza Amjadi, Jun-Ho Jeong, Eungsug Lee, Jung-Yong Lee, Inkyu Park. [email protected] Core-Shell Nanowire Network for Robust Transparent Electrodes Against Oxidation and Sulfurization. Small. 2014; 10 (20):4171-4181.

Chicago/Turabian Style

Hyeonjin Eom; Jaemin Lee; Aekachan Pichitpajongkit; Morteza Amjadi; Jun-Ho Jeong; Eungsug Lee; Jung-Yong Lee; Inkyu Park. 2014. "[email protected] Core-Shell Nanowire Network for Robust Transparent Electrodes Against Oxidation and Sulfurization." Small 10, no. 20: 4171-4181.

Journal article
Published: 14 April 2014 in ACS Nano
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The demand for flexible and wearable electronic devices is increasing due to their facile interaction with human body. Flexible, stretchable and wearable sensors can be easily mounted on clothing or directly attached onto the body. Especially, highly stretchable and sensitive strain sensors are needed for the human motion detection. Here, we report highly flexible, stretchable and sensitive strain sensors based on the nanocomposite of silver nanowire (AgNW) network and PDMS elastomer in the form of the sandwich structure (i.e., AgNW thin film embedded between two layers of PDMS). The AgNW network-elastomer nanocomposite based strain sensors show strong piezoresistivity with tunable gauge factors in the ranges of 2 to 14 and a high stretchability up to 70%. We demonstrate the applicability of our high performance strain sensors by fabricating a glove integrated with five strain sensors for the motion detection of fingers and control of an avatar in the virtual environment.

ACS Style

Morteza Amjadi; Aekachan Pichitpajongkit; Sangjun Lee; Seunghwa Ryu; Inkyu Park. Highly Stretchable and Sensitive Strain Sensor Based on Silver Nanowire–Elastomer Nanocomposite. ACS Nano 2014, 8, 5154 -5163.

AMA Style

Morteza Amjadi, Aekachan Pichitpajongkit, Sangjun Lee, Seunghwa Ryu, Inkyu Park. Highly Stretchable and Sensitive Strain Sensor Based on Silver Nanowire–Elastomer Nanocomposite. ACS Nano. 2014; 8 (5):5154-5163.

Chicago/Turabian Style

Morteza Amjadi; Aekachan Pichitpajongkit; Sangjun Lee; Seunghwa Ryu; Inkyu Park. 2014. "Highly Stretchable and Sensitive Strain Sensor Based on Silver Nanowire–Elastomer Nanocomposite." ACS Nano 8, no. 5: 5154-5163.