Nanoporous polymeric transmission gratings for high-speed humidity sensing

Abstract

Nanoporous polymeric transmission gratings are demonstrated to be an excellent platform for high-speed optical humidity sensing. The grating structures were fabricated with a modified holographic, polymer-dispersed liquid crystal (H-PDLC) system. The sensing mechanism was based on changes in the relative transmission associated with the adsorption and desorption of water vapour by nanopores. The spectral changes due to varying humidity levels were measured by a spectrometer and compared with the calculated results based on the coupled wave theory. When the relative humidity (RH) changed from 40% to 95%, the relative transmission at 475 nm increased from 6.3% to 46.6% and that at 702 nm increased from 4% to 64%; these results indicate the sensor's high sensitivity. In addition, the sensor demonstrated excellent reversibility and reproducibility over a large RH range (from 20% to 100% RH). Moreover, the response time of the sensor was measured to be less than 350 ms, making it suitable for many high-speed humidity-sensing applications.

Tunable optofluidic microlens through active pressure control of an air–liquid interface

“…Adaptive optical systems are critical in a variety of on-chip biological/chemical assays, including sensing (Levy and Shamai 2007;Zourob et al 2005;Shi et al 2007;Shi et al 2008a), microscopic imaging (Sinton et al 2003;Heng et al 2006;Cui et al 2008;Wu et al 2008), cell sorting (Wang et al 2005), particle manipulation (Monneret et al 2007;Shi et al 2008b;Blakely et al 2008), and single-particle detection/analysis (Yin et al 2007;Hunt and Wilkinson 2008;Yang et al 2009;Mao et al 2009a). However, most optical systems are currently made with solid materials (such as glasses, metals, and semiconductors) .…”

A Capacitive Humidity Sensor Based on an Electrospun PVDF/Graphene Membrane

“…Specifically, in the medical field, these sensors are used in respiratory equipment, incubators, sterilizers and biological products, where humidity control is very important [1,2,3,4]. Besides, there is an increasing demand for devices with optimum properties for different applications, in aspects such as cost, compatibility, sensibility and response time.…”

“…The humidity sensors research has generated a wide variety of devices composed of polymers, ceramics, blended materials, graphene (G)-based materials, and others [2,5,6,7,8,9,10,11,12,13,14]. The humidity level is obtained by measurement of either the electrical resistance or capacitance of the sensing material [4].…”

Towards nanoporous polymer thin film-based drug delivery systems

“…In particular, nanoporous polymer materials are attractive for polymeric DDS due to their low cost, biocompatibility, and biodegradability [11][12][13][14]. Thus far, porous polymeric structures have been fabricated by methods like mold replication [15], colloidal lithography [16], interfacial polymerization [17], nanoimprinting [18], electrospinning [19], track etching [20], templating [21][22][23], holographic lithography [24][25][26][27][28] and self-assembly [29][30][31]. Despite these advances, the fabrication of nanoporous polymer thin films is complex and slow.…”