Auxetic Mechanical Metamaterials to Enhance Sensitivity of Stretchable Strain Sensors

Jiang, Ying; Liu, Zhiyuan; Matsuhisa, Naoji; Qi, Dianpeng; Leow, Wan Ru; Yang, Hui; Yu, Jiancan; Chen, Geng; Liu, Yaqing; Wan, Changjin; Liu, Zhuangjian; Chen, Xiao

doi:10.1002/adma.201706589

Cited by 372 publications

(272 citation statements)

References 60 publications

Supporting

Mentioning

267

Contrasting

Order By: Relevance

“…Stretchable conductors are the basic building blocks of advanced flexible electronic devices, such as flexible display, skin‐like sensors, stretchable batteries, soft actuators and so forth . They are used in a vast number of soft and stretchable devices developed in recent years, including biointerfacing electrodes, transistors, mechanical sensors, energy devices and many more . To meet most application requirements, stretchable conductors need to remain conductive under tensile strain of more than 100%, and even more importantly, to show stable performance in terms of interfacial adhesion between conductive metal film and the supporting polymer substrate .…”

mentioning

confidence: 99%

Highly Stable and Stretchable Conductive Films through Thermal‐Radiation‐Assisted Metal Encapsulation

et al. 2019

Self Cite

View full text Add to dashboard Cite

Stretchable conductors are the basic building blocks of advanced flexible electronic devices, such as flexible display, skin-like sensors, stretchable batteries, soft actuators and so forth. [1][2][3][4][5][6][7][8][9][10] They are used in a vast number of soft and stretchable devices developed in recent years, including biointerfacing electrodes, [11][12][13][14][15] transistors, [16][17][18] mechanical sensors, [19][20][21][22] energy devices [23][24][25][26] and many more. [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] To meet most application requirements, stretchable conductors need to remain conductive under tensile strain of more than 100%, and even more importantly, to show stable performance in terms of interfacial adhesion between conductive metal film and the supporting polymer substrate.[1] Current methods to achieve stretchable conductors generally fall into two categories. One involves a structural design strategy, where the conducting material is designed with specific structures/topographies including serpentines, [46][47][48][49][50][51][52] wrinkles, [53,54] meshes, [55][56][57][58] and microcracks. [59][60][61][62][63] The other strategy relies on intrinsic stretchability of Stretchable conductors are the basic units of advanced flexible electronic devices, such as skin-like sensors, stretchable batteries and soft actuators. Current fabrication strategies are mainly focused on the stretchability of the conductor with less emphasis on the huge mismatch of the conductive material and polymeric substrate, which results in stability issues during long-term use. Thermal-radiation-assisted metal encapsulation is reported to construct an interlocking layer between polydimethylsiloxane (PDMS) and gold by employing a semipolymerized PDMS substrate to encapsulate the gold clusters/atoms during thermal deposition. The stability of the stretchable conductor is significantly enhanced based on the interlocking effect of metal and polymer, with high interfacial adhesion (>2 MPa) and cyclic stability (>10 000 cycles). Also, the conductor exhibits superior properties such as high stretchability (>130%) and large active surface area (>5:1 effective surface area/geometrical area). It is noted that this method can be easily used to fabricate such a stretchable conductor in a wafer-scale format through a one-step process. As a proof of concept, both long-term implantation in an animal model to monitor intramuscular electric signals and on human skin for detection of biosignals are demonstrated. This design approach brings about a new perspective on the exploration of stretchable conductors for biomedical applications.

show abstract

mentioning

confidence: 99%

Highly Stable and Stretchable Conductive Films through Thermal‐Radiation‐Assisted Metal Encapsulation

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…Among various application scenarios of different strain ranges, the requirement of sensitivity is different. For instance, high sensitivity (gauge factor ≥ 20) is a prerequisite for extracting the detailed medical information in radial pulse detection . By contrast, low‐sensitivity (gauge factor ≈ 1) is usually sufficient for the detection of large‐scale strain in a majority of joint movements .…”

mentioning

confidence: 99%

Mechanocombinatorially Screening Sensitivity of Stretchable Strain Sensors

et al. 2019

Self Cite

View full text Add to dashboard Cite

are often realized at the expense of stretchability, and vice versa. Hence, developing strain sensors with customizable sensitivity could be vital for reliable sensing. The sensitivity of resistive-type strain sensors is defined by gauge factor, GF = (ΔR/R 0 )/ε, where ΔR is the resistance change with strain, R 0 is the resistance before strain, and ε is the applied strain. [28] Currently, a large number of stretchable strain sensors are developed based on conductive materials, such as carbon nanotubes, graphene, metal networks, and liquid metal. [1,2,26,[29][30][31][32][33][34] The sensitivity is highly scattered and independent due to different sensing materials and diverse fabrication methods (Table S1, Supporting Information). Thus, it still remains a challenge to screen out the specific sensitivity from these traditional strain sensors.The resistive-type stretchable strain sensors are typically composed of conductive films and polymer substrates. [28,35,36] The mechanism involves the transfer of strain from the substrate to the conductive film during stretching, which induces cracks and thus increases electrical resistance; when the strain is released, the resistance returns to its initial value. [6] Hence, the strain distribution of polymer substrates largely determines the resistance-strain behavior of the conductive film, thereby determining sensitivity. According to mechanics of materials, strain is uniformly distributed over a mechanically homogeneous film ( Figure S1, Supporting Information). In contrast, taking a simplest mechanically heterogeneous film for example, strain is redistributed over the film, and local strain is determined by two factors, mechanics and structure parameters ( Figure S2, Supporting Information). Therefore, for the resistive-type stretchable strain sensors, the sensitivity could be screened via strain distribution of substrates. Based on finite element modeling (FEM), strain is indeed redistributed on mechanically heterogeneous substrates, which are composed of low and high modulus regions (Figure 1a,b). Numerous gradient structures can be precisely obtained by changing the parameter of substrates. By combining both mechanics and structure parameters of the substrates, a strategy we termed mechanocombinatorics, strain redistribution could be systematically studied. The strain enhancement is well customized by mechanically combined parameters, modulus ratio and pitch, which can be directly extracted from the strain enhancement library (Figure 1c). Stretchable strain sensors have aroused great interest for their application inhuman activity recognition, health monitoring, and soft robotics. For various scenarios involving the application of different strain ranges, specific sensitivities need to be developed, due to a trade-off between sensor sensitivity and stretchability. Traditional stretchable strain sensors are developed based on conductive sensing materials and still lack the function of customizable sensitivity. A novel strategy of mechanocombinatorics is proposed to scr...

show abstract

Section: Stretchable and Conformal Sensors For Cyber Biophysical Intementioning

confidence: 99%

“…For traditional elastic film, it expands longitudinally but compresses in the transverse direction. Expansion separates the conductive materials while Poisson compression squeezes the conductive materials . Hence, the former contributes to sensitivity but the latter intrinsically limits the sensitivity.…”

Section: Stretchable and Conformal Sensors For Cyber Biophysical Intementioning

confidence: 99%

“…The interesting feature of auxetic mechanical metamaterials is their 2D expansion due to their negative structural Poisson's ratio. Their bidirectional expansion promotes the separation of conductive materials and enhances the sensitivity of strain sensors by 24‐fold (Figure c) . These stretchable strain sensors can be attached on neck muscles, which is useful for the diagnosis of damaged vocal cords, respiratory disorders, and throat cancers.…”

Section: Stretchable and Conformal Sensors For Cyber Biophysical Intementioning

confidence: 99%

See 1 more Smart Citation

Cyber–Physiochemical Interfaces

et al. 2020

Self Cite

View full text Add to dashboard Cite

Living things rely on various physical, chemical, and biological interfaces, e.g., somatosensation, olfactory/gustatory perception, and nervous system response. They help organisms to perceive the world, adapt to their surroundings, and maintain internal and external balance. Interfacial information exchanges are complicated but efficient, delicate but precise, and multimodal but unisonous, which has driven researchers to study the science of such interfaces and develop techniques with potential applications in health monitoring, smart robotics, future wearable devices, and cyber physical/human systems. To understand better the issues in these interfaces, a cyber–physiochemical interface (CPI) that is capable of extracting biophysical and biochemical signals, and closely relating them to electronic, communication, and computing technology, to provide the core for aforementioned applications, is proposed. The scientific and technical progress in CPI is summarized, and the challenges to and strategies for building stable interfaces, including materials, sensor development, system integration, and data processing techniques are discussed. It is hoped that this will result in an unprecedented multi‐disciplinary network of scientific collaboration in CPI to explore much uncharted territory for progress, providing technical inspiration—to the development of the next‐generation personal healthcare technology, smart sports‐technology, adaptive prosthetics and augmentation of human capability, etc.

show abstract

Auxetic Mechanical Metamaterials to Enhance Sensitivity of Stretchable Strain Sensors

Cited by 372 publications

References 60 publications

Highly Stable and Stretchable Conductive Films through Thermal‐Radiation‐Assisted Metal Encapsulation

Highly Stable and Stretchable Conductive Films through Thermal‐Radiation‐Assisted Metal Encapsulation

Mechanocombinatorially Screening Sensitivity of Stretchable Strain Sensors

Cyber–Physiochemical Interfaces

Contact Info

Product

Resources

About