Abstract
Thin films with nanometer thicknesses in the range 100–400 nm are prepared from double hydrophilic copolymers of complex branched structures containing poly(N,N-dimethyl acrylamide) and poly(ethylene oxide) blocks and are used as humidity sensitive media. Instead of using glass or opaque wafer for substrates, polymer thin films are deposited on Bragg stacks and thin (30 nm) sputtered Au–Pd films thus bringing color for the colorless polymer/glass system and enabling transmittance measurements for humidity sensing. All samples are characterized by transmittance measurements at different humidity levels in the range from 5% to 90% relative humidity. Additionally, the humidity induced color change is studied by calculating the color coordinates at different relative humidity using measured spectra of transmittance or reflectance. A special attention is paid to the selection of wavelength(s) of measurements and discriminating between different humidity levels when sensing is performed by measuring transmittance at fixed wavelengths. The influence of initial film thickness, sensor architecture, and measuring configuration on sensitivity is studied. The potential and advantages of using top covered Bragg stacks and polymer/metal thin film structures as humidity sensors with simple optical read-outs are demonstrated and discussed.
Highlights
Humidity is present everywhere and is one of the mostly important physical parameters in our lives
In this study we prove the concept of utilization of top covered Bragg stacks and polymer/metal thin films as optical sensors for humidity
When polymer film or hydrogel are exposed to high humidity the polymer chains swell due to the pWenheetrnatpioolnyomfemr ofiilsmtuorer ihnysdidreogtheleafirlemexapnodsaesdatorehsiuglht thhueymcidhiatnygtehethpeoirlythmicekrncehsasi,nis.es.,wswelleldliunegtios tohbesperevneedtr.aStiiomnuolftamnoeoisutuslrye, iansdirdoepthine rfielfmraacntidveasinadreexsutaltktehsepylcahceandgueethtoeitrhtehircekdnuecsesd, i.dee.,nsswiteylloinf gthise ofiblmser[v32ed]..IStimmauyltbaneeeoxupselcyt,ead dthroapt tihne rdeefrgarceteivoef isnwdeelxlintagkdeseppelnacdes dounethtoe itnhietiraeldthuiccekdnedsesnosiftythoeffitlhme
Summary
Humidity is present everywhere and is one of the mostly important physical parameters in our lives. The accurate monitoring of humidity is significant in semiconductors, electronics, food processing, and pharmaceutical industries where the quality of products is influenced sufficiently by the humidity. Humidity control is essential in museums or archives in order to ensure the correct storage of artworks. Monitoring of relative humidity in office environments is in favor of human comfort and health and helps achieve hygienic conditions. The established technology nowadays is an electrical measurement of humidity [1] where the change of resistivity, dielectric constant, or the impedance of a sensitive medium, usually metal oxide thin film, is used [2,3]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
