Abstract
3D printing has attracted a lot of attention in recent years. Over the past three decades, various 3D printing technologies have been developed including photopolymerization-based, materials extrusion-based, sheet lamination-based, binder jetting-based, power bed fusion-based and direct energy deposition-based processes. 3D printing offers unparalleled flexibility and simplicity in the fabrication of highly complex 3D objects. Tactile sensors that emulate human tactile perceptions are used to translate mechanical signals such as force, pressure, strain, shear, torsion, bend, vibration, etc. into electrical signals and play a crucial role toward the realization of wearable electronics and electronic skin. To date, many types of 3D printing technologies have been applied in the manufacturing of various types of tactile sensors including piezoresistive, capacitive and piezoelectric sensors. This review attempts to summarize the current state-of-the-art 3D printing technologies and their applications in tactile sensors for wearable electronics and electronic skin. The applications are categorized into five aspects: 3D-printed molds for microstructuring substrate, electrodes and sensing element; 3D-printed flexible sensor substrate and sensor body for tactile sensors; 3D-printed sensing element; 3D-printed flexible and stretchable electrodes for tactile sensors; and fully 3D-printed tactile sensors. Latest advances in the fabrication of tactile sensors by 3D printing are reviewed and the advantages and limitations of various 3D printing technologies and printable materials are discussed. Finally, future development of 3D-printed tactile sensors is discussed.
Highlights
Epidermal electronic system or electronic skin has been introduced as a multifunctional electronic system to detect the physiological signals including temperature, pressure, strain and electrophysiological signals by integrating electrodes, various sensors, power supply and communication components onto a flexible and stretchable substrate [1]
Among all the components incorporated in an epidermal electronic system, flexible tactile sensors able to detect force, pressure, strain, shear, torsion, bend and vibration produced by human subtle touch, contact and movement play a very important role [10,14,15]
They designed a tactile sensor consisting of two sensing layers with straight piezoresistive line removal; and (c)500, piezoresistive ink injection or direct ink writing
Summary
Epidermal electronic system or electronic skin has been introduced as a multifunctional electronic system to detect the physiological signals including temperature, pressure, strain and electrophysiological signals by integrating electrodes, various sensors, power supply and communication components onto a flexible and stretchable substrate [1] These wearable artificial skin systems have important applications in biomedical engineering and health monitoring [1,2,3,4,5,6,7,8,9,10,11,12,13]. Among all the components incorporated in an epidermal electronic system, flexible tactile sensors able to detect force, pressure, strain, shear, torsion, bend and vibration produced by human subtle touch, contact and movement play a very important role [10,14,15] They require high sensitivity with the minimum detectable pressure as low as ~5 Pa [16,17]. Advantages and limitations of various 3D printing processes and future development of 3D-printed tactile sensors are discussed
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