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Posted: Jul 06, 2017
Toward 'invisible' wearable sensors with gold nanowires
(Nanowerk News) To build conformal contact of sensors with human skin/muscle with curvilinear surfaces, stretchable and bendable features are required – a capability impossible to achieve with existing rigid circuit board technologies.
To date, great progress has been utilized in fabricating skin-like strain sensors using a number of novel materials including metallic nanomaterials (metal nanoparticles, and metallic nanowires such as gold nanowires, silver nanowires, and copper nanowires), carbon nanomaterials (carbon blacks, graphene, and carbon nanotubes), and even ionic liquids.
Researchers in Australia now report on a transparent and stretchable strain sensor using percolating networks of 'soft' gold nanowires (AuNWs) and 'rigid' silver nanowires (AgNWs) which are fabricated through simple and solution-processable approach.
The team successfully fabricated a highly sensitive, transparent, bendable, and stretchable strain sensor based on the novel percolating networks of the 'soft' AuNWs and 'rigid' AgNWs.
With optimum sensor design, this sensor can achieve a high sensitivity with a gauge factor of 236.6 at low strain (≤5.0%), the ultralow strain detection as low as only 0.05% strain, the tunable transmittance from 58.7% to 66.7%, and the stretchability of about 70% strain while maintaining high sensing performance.
Moreover, the hybrid AgNW/AuNW-based sensor shows excellent durability as it can withstand up to 1000 stretching cycles at 10% strain and features low energy consumption (functioning at a low voltage of only 0.1 V).
Also reporting in this paper, the team further demonstrates the applications of their durable and transparent strain sensors in detecting human emotional expressions, respiration rate, and apexcardiograms.
"The unique attributes of our sensors in conjunction with simple yet cost-effective fabrication process indicate their potential real-world applications in next-generation 'invisible' and 'unfeelable' wearable technologies," the authors conclude.