Resistive humidity sensor using phosphonium salt-containing polyelectrolytes based on the mutually cross-linkable copolymers

Abstract

Two kinds of mutually cross-linkable copolymers were prepared to be used as humidity-sensing materials. The humidity-sensitive thin films consist of cross-linked polyelectrolytes of the following component: 4-vinylbenzyl dimethyl 2-(dimethylphosphino)ethyl phosphonium chloride (1)/ bis(2-methoxyethyl)itaconate (2)= 3/1, 2/1, 1/1 and 1/2 and 4-vinylbenzyl chloride (3)/ vinylbenzyl tributyl phosphonium chloride (4)= 3/1, 2/1, 1/1 and 1/2. The humidity sensor prepared from the reaction of 1/2= 2/1 with 3/4= 2/1 showed an average resistance of 723, 36.2 and 2.42 kΩ at 30, 60 and 90%RH, respectively. Temperature dependence, frequency dependence, and response time were measured and the reliability test such as water durability and long-term stability were also estimated.

Preparation of flexible resistive humidity sensors with different electrode gaps by screen printing and their humidity-sensing properties

“…[21][22][23][24][25][26] Their ionic moieties, such as cationic, anionic, and amphoteric, and their counter ions were directly related to sensitivity. 2,7,[27][28][29][30][31][32][33][34] In addition, the thickness of the humid membrane closely affects the humidity sensitivities, such as hysteresis and response time or recovery time. 35,36 The sensing characteristics of these humidity sensors are also dependent on the electrode gap size, which is related to the design of the electrode.…”

Anchoring of polyelectrolyte membrane containing chalcone group to electrode substrate by [2+2] cycloaddition and its humidity-sensing properties

“…[3][4][5][6][7][8][9][10][11][12][13][14][15] Many water resistive, humidity-sensitive materials with crosslinked structures were synthesized and reported in the literature. [3][4][5][6][7][8][9][10][11][12][13][14][15] High temperatures and humidity may accelerate the dissolution of the polyelectrolyte used for humidity sensors. Even though most humidity-sensitive polyelectrolytes were crosslinked, the polymer films are liable to swell, shrink, peel off or get loose from the electrode at high temperature and humidity.…”

Attachment of humidity-sensitive membranes to electrodes surface via photochemical reaction of benzophenone derivatives

“…[12][13][14][15][16] Among them, forming crosslinking structures in the sensitive film was proven to effectively improve their water-resistance and environmental stability. [17][18][19][20][21][22][23][24] However, the stability of these sensors is still insufficient to be used under severe conditions such as high temperature and high humidity or dewy atmosphere. Therefore, the development of the resistance-type humidity sensors being applicable under such severe conditions is greatly required.…”