Ultrafast colorimetric humidity-sensitive polyelectrolyte coating for touchless control

Yu, Li; Xu, Haolan; Monro, Tanya M.; Lancaster, David G.; Xie, Yi; Zeng, Hongbo; Chen, George G.; Liu, Xiaokong

doi:10.1039/c6mh00317f

Cited by 57 publications

(68 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A half and whole bilayer denote the coatings with PDDA and PSS as the outmost layer, respectively. The coating thickness for PDDA/PSS has been known to increase exponentially with the number of bilayers 12 , attributed to polyelectrolyte diffusion 19 . Although described as a multilayer, a PEM coating can be treated as an optically homogeneous layer due to: (a) negligible refractive-index variation across the coating due to polyelectrolyte diffusion; (b) sub-wavelength thickness of the individual layers; and (c) sub-wavelength diameter of the nanopores.…”

Section: Resultsmentioning

confidence: 99%

“…Electrical hygrometers are unsuitable for applications requiring the sensors to be compact and lightweight for good portability, flexible enough to probe in and retract from confined spaces, immune to electromagnetic interference (EMI), completely inert within combustive environments, and sufficiently robust to last a few years. Driven by these demands, fiber-optic hygrometers have emerged 5 – 12 , and they typically have response times ranging from tens of milliseconds to seconds. Existing hygrometers must be faster for applications that require faster temporal response, such as: (a) process control for mass production of chemical compounds 13 , 14 , where humidity is regulated as a part of quality assurance; (b) touchless keypads for information systems, where selectiveness to bare skin leads to less false triggers than capacitive/resistive-touch technologies; (c) water-hazard safety mechanisms for portable electronics (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, layer-by-layer-assembled polyelectrolyte multilayer (PEM) coatings featuring nanoporous-based hydrophilicity have been optically interrogated on silicon substrates for humidity-based touchless control, exhibiting a fast response time of 35 ms and wavelength shift of the reflectance spectrum exceeding 305 nm for 0–99%RH 12 (i.e. 6 × 10 −3 %RH detection limit for 20 pm wavelength resolution).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ultra-fast Hygrometer based on U-shaped Optical Microfiber with Nanoporous Polyelectrolyte Coating

Chen

Kang

et al. 2017

Sci Rep

Self Cite

View full text Add to dashboard Cite

Real-time measurement of the relative humidity of air has applications ranging from process control to safety. By using a microfiber form-factor, we demonstrate a miniature and fast-response hygrometer with the shortest-ever response time (3 ms). The sensor head consists of an optical microfiber of 10 µm diameter and 2 mm length configured to form a compact U-shaped probe, and functionalized with a polyelectrolyte multilayer coating of 1.0 bilayer. The sensing mechanism is primarily water-absorption-based optical loss. We have measured a response time of 3 ms and a recovery time of 36 ms. The sensitivity is as high as 0.4%/%RH, and the detection limit is as low as 1.6%RH. The maximum relative humidity is 99%RH, before reaching a recoverable dew-point.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ultra-fast Hygrometer based on U-shaped Optical Microfiber with Nanoporous Polyelectrolyte Coating

Chen

Kang

et al. 2017

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…Recently, the layer‐by‐layer‐assembled PEM coatings have been reported by a number of authors . The PEM thin film possesses the characters of nanoporous‐based hydrophilicity, which has been optically interrogated on silicon substrates for humidity–based touchless control, exhibiting a fast response time of 35 ms and wavelength shift of the reflectance spectrum exceeding 305 nm for 0–99%RH . However, the high sensitivity and fast response of PEM coating cannot be implemented simultaneously.…”

Section: Sensitive Materialsmentioning

confidence: 99%

Research Advances in Microfiber Humidity Sensors

Peng

Zhao

Chen

et al. 2018

Small

View full text Add to dashboard Cite

An overview of the numerous latest research in microfiber humidity sensors is carried out with a specific focus on measurement methods, humidity sensitive materials, probe structures, and sensing properties of different sensors. First, five mainstream measurement structures, including taper, fiber grating, coupler, resonator, and interferometer are reviewed. It is concluded that these measurement structures sense the physicochemical property variations of microfibers or sensitive films and exhibit the change of optical signal when exposed to environment. Second, the basic preparation methods, humidity‐sensing properties, and their advantages and disadvantages as humidity sensitive material are addressed. Then, the advantages and disadvantages of all the above sensing structures are also discussed and compared. Finally, the main existing problems and potential solutions of microfiber humidity sensors are pointed out.

show abstract

“…Although the humidity responsive behavior of LbL films has been extensively studied, their colorimetric humidity‐sensitive properties have not been reported much. Recently, a colorimetric humidity‐sensitive poly(diallyldimethylammonium) (PDDA)/PSS LbL film was developed for monitoring humidity change and demonstrated potential applications in touchless control of diodes or computers . In fact, humidity‐sensitive LbL films have not been explored for display/hiding well‐defined images with tunable structural colors.…”

Section: Introductionmentioning

confidence: 99%

Photopatternable Nanolayered Polymeric Films with Fast Tunable Color Responses Triggered by Humidity

Dong

Zhang

Wang

et al. 2019

Adv Funct Materials

View full text Add to dashboard Cite

Smart surfaces that can dynamically respond to environmental stimuli have demonstrated great promise in wearable electronics and optical detectors. Herein, a photopatternable nanolayered polymeric film that can reversibly display and hide structural colors in the visible range in response to relative humidity (RH) changes is reported. This film is fabricated on a silicon substrate using layer-by-layer assembly of chitosan and photoreactive carboxymethyl cellulose-azido derivative, and selectively crosslinked through UV irradiation from a photomask. Compared to crosslinked regions, un-crosslinked ones swell more and result in a larger thickness at high RH; as a result, those two regions show distinguishable color differences. The correlation of displayed color with film thickness at various RHs is plotted in an International Commission on Illumination (CIE) chromaticity diagram, which is in good agreement with the results obtained from modeling based on the interference theory. It is demonstrated that the structural color patterns on the film can be hidden and displayed spontaneously by contact with humid air, including human breath.This humidity-triggered color change is fast, of fine resolution, highly reversible, and compatible with most silicon-based devices. This film is low-cost, stable, and ready to be applied to large surface areas for potential applications in anticounterfeiting, humidity sensors, and optical color filters.

show abstract

Ultrafast colorimetric humidity-sensitive polyelectrolyte coating for touchless control

Abstract: A touchless control system that can be operated by a humidity signal is developed based on colorimetric humidity-sensitive materials.

Cited by 57 publications

References 51 publications

Ultra-fast Hygrometer based on U-shaped Optical Microfiber with Nanoporous Polyelectrolyte Coating

Ultra-fast Hygrometer based on U-shaped Optical Microfiber with Nanoporous Polyelectrolyte Coating

Research Advances in Microfiber Humidity Sensors

Photopatternable Nanolayered Polymeric Films with Fast Tunable Color Responses Triggered by Humidity

Contact Info

Product

Resources

About