A high-performance humidity sensor based on alkalized MXenes and poly(dopamine) for touchless sensing and respiration monitoring

Abstract

The typical mode of interaction between humans and machines in current intelligent equipment and personalized health care systems is mainly contact-type. However, there are severe problems associated with direct contact,...

Chitosan-Based Highly Sensitive Viable Humidity Sensor for Human Health Monitoring

“…Ullah et al reported a highly sensitive, flexible, and eco-friendly biodegradable nonwoven paper-based humidity sensor on polyethylene terephthalate (PET) substrate with copper tape as electrodes and demonstrated its applications in health and medicine . In recent work, Li et al proposed a flexible humidity sensor based on alkalized MXenes and polydopamine for human–machine interaction in a noncontact manner . Such studies suggest the emerging application of humidity sensors in determining human health severities related to respiration and skin moisture.…”

Fast response flexible humidity sensors based on Ti3C2Tx MXene-heterostructures for multifunctional applications

“…In 2017, the first Ti 3 C 2 T x MXene humidity sensor was demonstrated, 24 and various strategies have been explored to boost their sensing performance. Ion intercalation (K + , Mg 2+ , or Na + ), 25 and hybridization with Ag, 26 TiO 2 , 27 K 2 Ti 4 O 9 , 28 and water-sensitive polyelectrolytes 29–31 have been utilized to promote the responsiveness (response and recovery time) of the MXene humidity sensors. Moreover, Ti 3 C 2 T x MXene has proved to be sensitive to low concentrations of gas vapors, 32,33 and thus the pristine Ti 3 C 2 T x may display a poor selectivity for water.…”

Covalently Functionalized MXenes for Highly Sensitive Humidity Sensors

“…Ion intercalation [ 45 ] (e.g., K + , Mg 2+ , or Na + ) in the pristine MXenes structures has been used to promote the diffusion of water in the material, improving its sensitivity toward moisture. Hybridization with Ag nanowires, [ 46 ] titanium dioxide (TiO 2 ), [ 47 ] K 2 Ti 4 O 9 nanowires, [ 48 ] and water‐sensitive polyelectrolytes such as poly(vinyl alcohol) (PVA), [ 49 ] poly(dopamine) (PDA), [ 50 ] or poly(diallyldimethylammonium chloride) (PDAC) [ 51 ] has been employed to increase the responsiveness (i.e., response and recovery time) of pristine MXenes. The intercalation of TiOF 2 nanospheres [ 52 ] in the pristine MXenes, or their hybridization with sodium ascorbate [ 53 ] or sodium alginate [ 54 ] showed improved long‐term stability.…”