Wearable electronics for intelligent sensing of patient body and physical activity is an important futuristic technology. Conventional strain sensors are rigid and not suitable for use on uneven surfaces such as human skin.
Study: Stretchable strain sensor based on reduced graphene oxide for monitoring physical activities and minute movements. Image Credit: metamorworks/Shutterstock.com
New work published in the journal Materials Today: Proceedings describes the construction of extremely flexible, precise and robust strain sensors using electrochemically produced reduced graphene oxide (rGO).
Wearable Electronics: The Future of Surveillance Devices
Consumers in the medical and health sector are gradually migrating towards controlled, personalized and monitored health care. The rapid evolution of mobile devices has contributed to the popularity of portable devices. Wearable technologies are emerging as excellent monitoring devices for health services as a result of these improvements, especially with an increased focus on wellness, wellness, and disease management.
Wearable electronic devices are sophisticated Internet of Things gadgets that collect biometric information such as sleep patterns and pulse rate. Wearable devices are used by consumers to properly transmit vital exercise, physiological and medical data to a database, which can be used to monitor patient health.
The world has recently felt the need to monitor wireless healthcare with the outbreak of the devastating coronavirus SARS-CoV-2. As a result, scientists have attempted to develop smart wearable gadgets for continuous, real-time detection of patients’ health and physical activity.
Limitations of traditional strain sensors
Conventional silicon-based strain sensors have relatively low flexibility of less than 5% and inadequate responsiveness, making them unsuitable for detecting small and large strains. Besides flexibility strain, typical silicon-based strain sensors require sophisticated fabrication procedures such as microelectromechanics and thin film deposition.
Requirements for advanced portable devices
Flexibility, responsiveness and endurance are essential characteristics of wearable devices, as they facilitate the integration of sensors on non-uniform interfaces such as the human body. Besides elasticity, these products also need a sensor capable of detecting minute deformations caused by physiological factors and physical activity.
Strain sensors used in wearable electronics must be structurally flexible to conform to soft, curved surfaces such as human skin, chemically inert to perspiration, and resistant to climatic variables such as temperature and humidity fluctuations.
Experiments on flexible strain sensors are currently underway, with an emphasis on using nanoscale carbon materials to avoid the difficulties associated with rigid nonmetals and semiconductors. Nanoscale carbon compounds can be used to make extremely flexible strain sensors.
Flexible Reduced Graphene Oxide (rGO) Strain Sensors
Due to its exceptional electrical and magnetic capabilities, graphene has been touted as a potential sensing material. By using electrochemically separated rGO flakes and a flexible silicone-based sealant, a robust, durable, cost-effective, highly elastic, ultra-sensitive, and long-lasting strain sensor was developed in this work.
An X-ray diffractometer (XRD) and a field-emission scanning electron microscope (FESEM) were used to analyze rGO. rGO/silicone strain sensors were later used in wearable devices to track many physiological movements such as hand bending, wrist rotation, finger flexion, and knee rotation. The fabricated sensor was also used to identify disturbances in hazardous containers and detect physical activities mentioned above.
Important Study Findings
The researchers used the electrolytic approach to create a large-scale rGO flake, and its characteristics were evaluated using FESEM, XRD, a pull-and-bend machine, and a multimeter. The suggested manufacturing technique is simple, environmentally friendly and cost effective. The combination of large flakes of rGO and an elastic silicone paste contributed to the development of a potential flexible strain sensor with 116% flexibility, 4100 sensitivity and 4550 cycle endurance.
Sensor flexibility results from body movement, which causes conductive channels to split and reconnect, changing the resistivity of the rGO/silicone detector. First, the rGO/silicone sensor was installed on the heels to observe the reaction of the sensor during walking and running. The sensor displayed a consistent pattern corresponding to the physical activity performed.
It can be inferred that the real-time feedback of the sensor can be applied to track physical activity such as unexpected jumps and falls. Additionally, the use of the flexible strain sensor is not limited to wearable technology; it can also be used in a variety of industries such as structural mapping and monitoring, automation, human-computer interaction, and touch recognition.
Verma, RP et al. (2022). Stretchable strain sensor based on reduced graphene oxide for monitoring physical activities and minute movements. Materials Today: Reviews. Available at: https://www.sciencedirect.com/science/article/pii/S2214785322031856?via%3Dihub