Researchers recently developed e-skin devices that can be used for diagnostic tools and prosthetics and rehabilitation, human-machine interfaces, optogenetics, and human-computer interaction in gaming, among others.
As specified in a Nanowerk report, the fast development of these ultra-thin e-skins or electronic skins, also known as epidermal electronics or electronic tattoos, has opened new realms of probability for both flexible and stretchable "monitoring gadgets" that can be worn directly on the skin. E-skins necessitate equally thin and flexible pressure sensors with a large response range, not to mention high sensitivity.
The de devices' pressure-sensitive performance can typically be assessed via various basic characteristics in terms of stability-durability, response-recovery rate, sensitive response, and detection range which also offer a reference for the useful design of the sensor.
MXene-Based Approach
Among these characteristics, the detection range and sensitive response are the two key factors affecting sensor property. Researchers reported an MXene-based approach to designing the e-skins' sensing material to meet the two needs mentioned.
As the study authors reported in ACS Applied Materials and Interfaces, they invented a flexible pressure sensor by "sandwiching a conductive MXene/ZIF-67/PAN film" between copper electrodes and PDMS.
Gaining benefits from the special rough and porous structure and the nanofiber film's 3D stable conductive network, the researcher's sensor can simultaneously attain a wide sensing range and high sensitivity, and display mechanical solid stability of more than 10,000 cycles and fast response-recovery time.
As illustrated and described in the study, to invent their e-skin sensor, the research team initially obtained flexible nanofiber films with rough structures through "in situ embedding" of metal-organic framework or MOF particles on flexible PAN nanofibers.
Sensor, a Competitive Candidate for Flexible, Wearable Health Devices
Combining MXene nanosheets into these films resulted in three-dimensional conductive network construction. As the researchers pointed out, the distinctive rough nanostructure of such MXene/ZIF-67/PAN film enables better connection of conductive pathways when force is applied, contributing to the ultrahigh sensitive response and the assembled flexible device's broad sensing range.
As a result, the researchers concluded their work by noting that the properties' excellent sensing, paired with encouraging benefits like good biocompatibility and high flexibility, is making this sensor a competitive candidate for flexible and wearable health devices.
Metal-Organic Framework
NovoMOF describes metal-organic frameworks as "compounds of metal ions" and organic molecules forming structured frameworks.
These advanced materials are comparable to sponges that have extraordinary abilities to take up, hold, and eventually release molecules from their pores.
Consequently, MOFs are the fastest-growing class of materials in chemistry at present. By fast, it means over 20,000 MOFs have been in the past two decades.
Essentially, by making MOF from different metal atoms and organic linkers, researchers can fabricate materials that are selectively absorbing gases into tailor-made pockets within the construction.
Therefore, MOFs provide great potential specifically for their effective incorporation and exploration in different sensing applications. They can be bot together randomly like the bricks of a Lego set and outdo each previously identified material regarding flexibility.
Related information about metal-organic frameworks is shown on Instituto de Ciencia Molecular's YouTube video below:
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