In an article recently published in the journal ACS Materials Letters, researchers presented a detailed discussion on the challenges associated with electronic skin materials and devices.
Study: Challenges in Materials and Devices of Electronic Skin. Image Credit: Lorenzo Sala/Shutterstock.com
Electronic skin is a flexible and wearable electronic system that mimics the functions and mechanical qualities of biological skin, and it has received a lot of attention in recent years. As a result, these skin-like electronics outperform typical cumbersome equipment in terms of mobility and functionality, garnering increased interest in the fields of soft robots, prostheses, and health monitoring.
To address the aforesaid mechanical and electronic criteria for electronic skins, much research has been carried out with an emphasis on synthesizing flexible materials, as well as constructing stretchy structures and extremely sensitive wearable sensors.
Although efforts have been made to incorporate skin-like electronics in a variety of applications ranging from everyday healthcare to advanced robotics, enormous challenges such as immature material selection and unbalanced device performance have stymied the commercialization process. Electronic skins still require compact integration methodologies rather than merely stacking to include advanced bionic features, array implementation, and biocompatible designs in order to obtain competitive advantages over traditional electronics.
About the Study
In the present study, the authors presented the difficulties associated with the design of electronic skins. They investigated the effects of deformation on electrical characteristics, issues in measuring precision and stability, constructive integration of multisensories, manufacturing skills, and processes for large-scale production. They highlighted these issues from the perspectives of device preparation, material modification, system design, and device preparation as well as possible research areas.
Some insights from materials, systems, and devices were presented to provide a holistic approach for designing and manufacturing skin-like electronics at the system level. The impact of deformation on repeated usage, sensor performance, and advanced functionalities was discussed.
The future development trend and potential of electronic skins in a wide range of applications were also discussed. Specific materials were chosen to ensure flexibility and stretchability, allowing devices and systems to adapt well to the surface of a detected item with deformation. The general state of development and current obstacles on the impact of deformation for electronic skin were reviewed.
In many studies, an insulator was utilized as a substrate, as well as a dielectric and packaging layer. Due to their high stretchability and flexibility, polymers were commonly used. The mechanical properties of polymeric materials were considerably enhanced by synthetically creating molecular and polymer chains. Several studies reported that electronic components were made of active, conductive, and soft materials such as metal-based materials, carbon-based materials, conductive polymers, semiconductive polymers, and two-dimensional materials.
Even after 1000 cycles, the mobility of the transistor based on such semiconductors displayed stable retention capabilities. With a water content of 90.8%, the hydrogel's inherent multilength scale structure demonstrated excellent softness and good strength. In one of the studies, the stretchy conductor's interface and the interlocking structure between gold and polydimethylsiloxane (PDMS) showed high adhesion (>2 MPa) and cycle stability (>10 000 cycles).
With a high degree of linear fitting, i.e., 0.997, a pre-stretched reduced graphene oxide (rGO) film on elastic tape showed working ranges up to 60% strain. Furthermore, the printed asymmetric micro-supercapacitors (AMSC) showed excellent capacitance retention of 96% over 20000 cycles, which implied that 3D layered materials could be useful functional materials for large-scale printing.
In conclusion, this study elucidated the mechanical characteristics, comprehensive sensory performance, bionic functionality, and potential applications of electronic skins, along with their significant hurdles and recent endeavors. The authors discussed possible optimization approaches on materials and device structures. They also reviewed recent advancements in bionic function application challenges, such as self-healing, multimodal detection, array-based perception, and biocompatibility. They emphasized that these capabilities lay the groundwork for real-world applications such as sophisticated robotic hands and obtaining various physiological signals.
According to the observations, a fully integrated electronic skin system should also contain a signal processing module, an energy supply unit, and a feedback effector. Flexible batteries, self-powering methodologies, and wireless powering are among the current research topics in electronic skin energy supply, which is critical to electronic components. Also, the development of high-performance organic and low-dimensional material-based transistors could aid in the creation of circuits that are more flexible.
Although significant progress has been made in the fabrication of logic units, analog computing circuits, and intelligent sensors, future research should focus on difficulties that impede large-scale deployment. The authors believe that adding an effector into an electronic skin system offers a lot of potential for expanding the range of its applications.
Zhang, J., Li, J., Cheng, W., et al. Challenges in Materials and Devices of Electronic Skin. ACS Materials Letters, (4) 577-599 (2022). https://pubs.acs.org/doi/10.1021/acsmaterialslett.1c00799