|Posted: Aug 10, 2017|
All-carbon humidity sensor handwritten on paper(Nanowerk News) In a new paper in ACS Applied Materials & Interfaces ("Drawn on Paper: A Reproducible Humidity Sensitive Device by Handwriting"), researchers in China describe the design of a type of full carbon-based humidity sensor by handwriting electrodes and the sensitive materials on paper substrates.
|Full carbon-based humidity sensor by handwriting electrodes and the sensitive materials on paper substrates. (© ACS) (click on image to enlarge)|
|The researchers used a commercial pencil to fabricate electrodes, and oxidized multiwalled carbon nanotubes (o-MWCNTs) were utilized as the sensitive material for the ink marker.|
|The marker was fabricated by injecting the ink (aqueous dispersion of o-MWCNTs) in the refill of a blank maker and drawing on the sensitive region of devices.|
|The team reports that the o-MWCNTs exhibit excellent dispersibility in water with good stability, which is beneficial for the solution process.|
|Compared with solid-state process, solution processes could introduce the sensitive material into the top layer of paper and form a structure of o-MWCNTs loaded porous cellulose layer by a permeating process.|
|Such structure could increase the contact area between the sensitive material and water molecules; meanwhile, the top layer of hydrophilic cellulose paper could participate in the water adsorption process and enhance the response of the humidity sensor.|
|Furthermore, the formation of sensitive layer does not rely on the abrasion between the substrate and bulk made from the sensitive material, which is beneficial for maintaining the completeness of electrodes.|
|According to the authors, the structure of the obtained paper-based humidity sensor mainly exhibits the following advantages:|
|The resultant devices are flexible, disposable, and potentially wearable, and meanwhile, the solution-based process is feasible for inkjet printing, which is possible for batch production.|
|By Michael Berger – Michael is author of two books by the Royal Society of Chemistry: Nano-Society: Pushing the Boundaries of Technology and Nanotechnology: The Future is Tiny.|
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