Electronic Muscles and Skins: A Review of Soft Sensors and Actuators (original) (raw)
Related papers
2009
A growing need for ambient electronics in our daily life leads to higher demands from the user in the view of comfort of the electronic devices. Those devices should become invisible to the user, especially when they are embedded in clothes (e.g. in smart textiles). They should be soft, conformable and to a certain degree stretchable. Electronics for implantation on the other hand should ideally be soft and conformable in relation to the body tissue, in order to minimize the rejecting nature of the body to unknown implanted rigid objects. Conformable and elastic circuitry is an emerging topic in the electronics and packaging domain. In this contribution a new low cost, elastic and stretchable electronic device technology will be presented, based on the use of a stretchable substrate. The process steps used are standard PCB fabrication processes, resulting in a fast technology transfer to the industry. This new developed technology is based on the combination of rigid standard SMD components which are connected with 2-D spring-shaped metallic interconnections. Embedding is done by moulding the electronic device in a stretchable polymer. The reliability of the overall system is improved by varying the thickness of the embedding polymer, wherever the presence and type of components requires to. Manufacturability issues are discussed together with the need for good reliability of the stretchable interconnections when stress is applied during stretching.
Mechanical Designs for Inorganic Stretchable Circuits in Soft Electronics
Mechanical concepts and designs in inorganic circuits for different levels of stretchability are reviewed in this paper, through discussions of the underlying mechanics and material theories, fabrication procedures for the constituent microscale/nanoscale devices, and experimental characterization. All of the designs reported here adopt heterogeneous structures of rigid and brittle inorganic materials on soft and elastic elastomeric substrates, with mechanical design layouts that isolate large deformations to the elastomer, thereby avoiding potentially destructive plastic strains in the brittle materials. The overall stiffnesses of the electronics, their stretchability, and curvilinear shapes can be designed to match the mechanical properties of biological tissues. The result is a class of soft stretchable electronic systems that are compatible with traditional high-performance inorganic semiconductor technologies. These systems afford promising options for applications in portable biomedical and health-monitoring devices. Mechanics theories and modeling play a key role in understanding the underlining physics and optimization of these systems.
Advances in Rational Design and Materials of High‐Performance Stretchable Electromechanical Sensors
Small, 2020
An effective solution is using stretchable intrinsic materials and stretchable structural designs to form mechanical sensors. [7,8] Compared to conventional rigid sensors, it is desirable for stretchable sensors to provide mechanical robustness, biocomparability, multifunctionality, as well as comfort of wearing such sensors. [9,10] Stretchable electromechanical sensors are capable of being comfortably attached on the human body and skin and perceiving mechanical stimuli. These sensors have huge potential applications in personal healthcare, including detection of human motion/gesture, breath, and pulse monitoring. Stretchable electromechanical sensors have recently attracted great interest due to their high sensitivity, stretchability, simplicity in design, and implementation. Compared with the other kinds of sensors, for example, stretchable piezoelectric/triboelectric sensors, electromechanical sensors usually require supply power or battery. A stretchable sensor typically consists of a sensing block embedded or integrated into a stretchable substrate that can be elongated under application of mechanical stimuli. [11,12] The sensing block acts as a mechanical sensing unit, which for instance converts stress/strain into a measurable electrical signal. The presence of nanomaterials and composites in the sensing block has been utilized as a preferable design for stretchable sensors. [11,13] Selection criteria of these materials include structural stretchability, suitable conductivity, and high mechanical strength. Designing the sensing structure aims for high sensitivity, fast response, linearity, and a wide working range. [14,15] The integration of nanomaterials and nanocomposites into stretchable sensors are currently an emerging trend of wearable sensors in their research, development, and commercialization. [10,11] The development of stretchable sensors with low power consumption for portable applications is also of great interest. [16,17] The conventional design method for "partly stretchable" sensing devices integrates "hard" sensors and "soft" interconnects to form "island-interconnect" configurations. [18,19] This approach deploys an isolated island to carry the rigid sensors and a stretchable network of interconnections. Geometric engineering structures including serpentine and fractal designs have been widely employed, to achieve stretchability Stretchable and wearable sensor technology has attracted significant interests and created high technological impact on portable healthcare and smart human-machine interfaces. Wearable electromechanical systems are an important part of this technology that has recently witnessed tremendous progress toward high-performance devices for commercialization. Over the past few years, great attention has been paid to simultaneously enhance the sensitivity and stretchability of the electromechanical sensors toward high sensitivity, ultra-stretchability, low power consumption or selfpower functionalities, miniaturisation as well as simplicity in design and fabrication. This work presents state-of-the-art advanced materials and rational designs of electromechanical sensors for wearable applications. Advances in various sensing concepts and structural designs for intrinsic stretchable conductive materials as well as advanced rational platforms are discussed. In addition, the practical applications and challenges in the development of stretchable electromechanical sensors are briefly mentioned and highlighted.
Applications of flexible and stretchable threedimensional structures for soft electronics
Soft Science, 2023
The development of devices that can be mechanically deformed in geometrical layouts, such as flexible/stretchable devices, is important for various applications. Conventional flexible/stretchable devices have been demonstrated using two-dimensional (2D) geometry, resulting in dimensional constraints on device operations and functionality limitations. Accordingly, expanding the dimensions in which such devices can operate and acquiring unique functionality that is difficult to implement in 2D planar structures remain challenging. As a solution, the development of a flexible/stretchable device embedding a three-dimensional (3D) structure fabricated through the precise control of a 2D structure or direct construction has been attracting significant attention. Because of a significant amount of effort, several 3D material systems with distinctive engineering properties, including electrical, optical, thermal, and mechanical properties, which are difficult to occur in nature or to obtain in usual 2D material systems, have been demonstrated. Furthermore, 3D advanced material systems with flexibility and stretchability can provide additional options for developing devices with various form factors. In this review, novel fabrication methods and unprecedented physical properties of flexible/stretchable 3D material systems are reviewed through multiple application cases. In addition, we summarized the latest advances and trends in innovative applications implemented through the introduction of advanced 3D systems in various fields, including microelectromechanical systems, optoelectronics, energy devices, biomedical devices, sensors, actuators, metamaterials, and microfluidic systems.
Nanomaterials
With the recent great progress made in flexible and wearable electronic materials, the upcoming next generation of skin-mountable and implantable smart devices holds extensive potential applications for the lifestyle modifying, including personalized health monitoring, human-machine interfaces, soft robots, and implantable biomedical devices. As a core member within the wearable electronics family, flexible strain sensors play an essential role in the structure design and functional optimization. To further enhance the stretchability, flexibility, sensitivity, and electricity performances of the flexible strain sensors, enormous efforts have been done covering the materials design, manufacturing approaches and various applications. Thus, this review summarizes the latest advances in flexible strain sensors over recent years from the material, application, and manufacturing strategies. Firstly, the critical parameters measuring the performances of flexible strain sensors and material...
Design of Strain‐Limiting Substrate Materials for Stretchable and Flexible Electronics
Advanced Functional Materials, 2016
Recently developed classes of electronics for biomedical applications exploit substrates that offer low elastic modulus and high stretchability, to allow intimate, mechanically biocompatible integration with soft biological tissues. A challenge is that such substrates do not generally offer protection of the electronics from high peak strains that can occur upon large‐scale deformation, thereby creating a potential for device failure. The results presented here establish a simple route to compliant substrates with strain‐limiting mechanics based on approaches that complement those of recently described alternatives. Here, a thin film or mesh of a high modulus material transferred onto a prestrained compliant substrate transforms into wrinkled geometry upon release of the prestrain. The structure formed by this process offers a low elastic modulus at small strain due to the small effective stiffness of the wrinkled film or mesh; it has a high tangent modulus (e.g., >1000 times the...
Polymers
Soft stretchable sensors rely on polymers that not only withstand large deformations while retaining functionality but also allow for ease of application to couple with the body to capture subtle physiological signals. They have been applied towards motion detection and healthcare monitoring and can be integrated into multifunctional sensing platforms for enhanced human machine interface. Most advances in sensor development, however, have been aimed towards active materials where nearly all approaches rely on a silicone-based substrate for mechanical stability and stretchability. While silicone use has been advantageous in academic settings, conventional silicones cannot offer self-healing capability and can suffer from manufacturing limitations. This review aims to cover recent advances made in polymer materials for soft stretchable conductors. New developments in substrate materials that are compliant and stretchable but also contain self-healing properties and self-adhesive capab...
Flexible and Stretchable Electronics: Current Status and Future Scope
Research & Reviews: Journal Of Engineering And Technology, 2019
Flexible and stretchable electronics have been subjects of interest for decades to scientists and industrial manufacturers. Ongoing research is trying to prove instrumental towards making this a reality with through technical verifications and analysis. These should then be suitable for production. Starting with metals and semiconductor substrates, interest has now veered to organic polymers and graphene. However, problems still remain. This review article discusses the properties of different materials and possible processes by which stretchable devices can be manufactured in the near future.
Fabrication Approaches to Interconnect Based Devices for Stretchable Electronics: A Review
Materials (Basel, Switzerland), 2018
Stretchable electronics promise to naturalize the way that we are surrounded by and interact with our devices. Sensors that can stretch and bend furthermore have become increasingly relevant as the technology behind them matures rapidly from lab-based workflows to industrially applicable production principles. Regardless of the specific materials used, creating stretchable conductors involves either the implementation of strain reliefs through insightful geometric patterning, the dispersion of stiff conductive filler in an elastomeric matrix, or the employment of intrinsically stretchable conductive materials. These basic principles however have spawned a myriad of materials systems wherein future application engineers need to find their way. This paper reports a literature study on the spectrum of different approaches towards stretchable electronics, discusses standardization of characteristic tests together with their reports and estimates matureness for industry. Patterned copper...