One-Step Laser Encapsulation of Nano-Cracking Strain Sensors

Abstract

Development of flexible strain sensors that can be attached directly onto the skin, such as skin-mountable or wearable electronic devices, has recently attracted attention. However, such flexible sensors are generally exposed to various harsh environments, such as sweat, humidity, or dust, which cause noise and shorten the sensor lifetimes. This study reports the development of a nano-crack-based flexible sensor with mechanically, thermally, and chemically stable electrical characteristics in external environments using a novel one-step laser encapsulation (OLE) method optimized for thin films. The OLE process allows simultaneous patterning, cutting, and encapsulating of a device using laser cutting and thermoplastic polymers. The processes are simplified for economical and rapid production (one sensor in 8 s). Unlike other encapsulation methods, OLE does not degrade the performance of the sensor because the sensing layers remain unaffected. Sensors protected with OLE exhibit mechanical, thermal, and chemical stability under water-, heat-, dust-, and detergent-exposed conditions. Finally, a waterproof, flexible strain sensor is developed to detect motions around the eye, where oil and sweat are generated. OLE-based sensors can be used in several applications that are exposed to a large amount of foreign matter, such as humid or sweaty environments.

Moving beyond flexible to stretchable conductive electrodes using metal nanowires and graphenes

“…They are dominant in new structural layouts strategy and the interfacial state between the polymer and conductive film determines the type of failure. 20 Cracking occurs under tensile strain or in a strongly adhered film, whereas channelling occurs under compressive strain or in a weakly adhered film. However, in spite of the remarkable stretchability and flexibility of electrodes with the new structural layout, the complicated fabrication and low transparency hinder integration of theses optoelectronic devices over a large area.…”

Realizing the high energy density and flexibility of a fabric electrode through hierarchical structure design

“…The NiPS 3 /NCNF free-standing electrode was bent to 120°, 180°and 360°to simulate the practical working conditions. 44,45 The testing method is shown in Fig. 7a and b.…”

Approaches for Solution-Processed Encapsulation of Printed Medical Wearable Devices

“…In barrier foil lamination, a barrier foil is attached to the substrate mostly by using adhesion, thermal or laser welding. One example is discussed in [22]. Here, an one-step laser encapsulation of a nano-cracking strain sensor was applied.…”