Water-resistive humidity sensor prepared by printing process using polyelectrolyte ink derived from new monomer

Abstract

A simple strategy was developed based on a new monomer containing both photocurable function and ammonium salt, N-(2-cinnamoyloxy)ethyl-N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl ammonium bromide (CMDAB) to obtain photocurable polyelectrolyte ink and stable humidity-sensitive membranes by printing process. Humidity-sensitive membranes are photocrosslinked polyelectrolytes obtained from copolymers of [2-(methacryloyloxy)ethyl] dimethyl propyl ammonium bromide (MEPAB), CMDAB and MMA. A flexible gold electrode/polyimide was pretreated with 2-(mercaptoethyl) cinnamamide (MEC) containing a thiol-coupling agent for the purpose of anchoring the humidity-sensitive polyelectrolyte to the gold electrode. The sensors using screen printing methods reduced the deflection of sensor characteristics showing humidity precision ±1%RH. The photocured copolymer MEPAB/CMDAB/MMA = 63/7/30 show good sensitivity (0.0586 logΩ/%RH) changing resistance approximately four orders of magnitude with relative humidity varying from 20% to 95% and fast response and recovery time. The resultant sensors showed acceptable linearity (Y = -0.04X + 7.0, R(2) = -0.9900) and small hysteresis. The reliability including water resistance and a long-term stability were estimated for the application of the flexible humidity sensor prepared by screen printing process.

Preparation of flexible resistive micro-humidity sensors using quaternary ammonium salt-modified graphene oxide and their humidity-sensing properties

“…This result demonstrates that GO-GTMAC did not influence the humidity-sensing characteristics compared with other quaternary ammonium salt-containing humidity sensors. 31 Figure 8 shows a plot of resistance of the sensor as a function of applied voltage at 1 kHz and 25 o C. Deviation of the humidity sensing curve at lower applied voltages (<0.5 V) was about 7.9±0.10%RH/V between 70 and 90%RH. How- Humidity-sensing graphene oxide modified with glycidyltrimethylammonium chloride film with thickness of 1 and 2 μm.…”

“…A substantial rise over 20 s was followed by a more gradual rise until the sensor was equilibrated at 94% RH. The other humidity sensors using polyelectrolyte films showed values for response time between 60 and 120 s. [29][30][31][32] Conclusions Micro-humidity sensors were constructed from a modified GO film with quaternary ammonium salts fabricated on an interdigitated electrode on flexible polyimide substrate of size 2.0×3.0 mm 2 . GO-GTMAC was uniquely selective for GO-based humidity sensors.…”

AC Complex Impedance Study on the Resistive Humidity Sensors with Ammonium Salt-Containing Polyelectrolyte using a Different Electrode Pattern

“…[2-(Methacryloyloxy)ethyl] propyl dimethyl ammonium bromide (MEPAB) was synthesized by a quaternization reaction of 2-(N,N-dimethylamino)ethyl methacrylate with n-propyl bromide. 16 Methyl methacrylate (MMA), ethylene glycol (EG), and azobisisobutyronitrile (AIBN, Aldrich Chemical, St. Louis, MO, USA) were used as received. 2-Methoxyethanol was dried with calcium hydride and sodium metal and purified by distillation.…”

“…4,5,[9][10][11][12][13][14] The thickness of the polyelectrolyte closely affects the humidity sensitivities, such as hysteresis and response or recovery time. 15,16 In addition, IDEs-type humidity sensors exhibited a significant change in impedance with a change in the number of fingers and gap size between electrode fingers, which are related to the design of the electrode. For practical applications, these techniques are expected to optimize the humidity-sensing characteristics precisely.…”

Water-resistive humidity sensor prepared from new polyelectrolyte containing both photo-curable 4-styrylpyridinium function and thiol anchor

“…The resistance was measured using an LCZ meter (Model EDC-1635, 0.1 -20 M ). The interdigitated gold electrodes were produced by first printing nano silver paste (thickness 6-7 m), followed by electroless plating of Cu (thickness 5 m), Ni (thickness 2 m) and then Au (thickness 80 nm) [32]. The flexibility of sensors was sufficient and a good electrical performance was achieved during a bent.…”