Paper-Based ZnS:Cu Alternating Current Electroluminescent Devices for Current Humidity Sensors with High–Linearity and Flexibility

Abstract

Humidity sensors are indispensable for various electronic systems and instrumentations. To develop a new humidity sensing mechanism is the key for the next generation of sensor technology. In this work, a novel flexible paper-based current humidity sensor is proposed. The developed alternating current electroluminescent devices (ACEL) consist of the electroless plating Ni on filter paper and silver nanowires (AgNWs) as the bottom and upper electrodes, and ZnS:Cu as the phosphor layer, respectively. The proposed humidity sensor is based on ACEL with the paper substrate and the ZnS:Cu phosphor layer as the humidity sensing element. The moisture effect on the optical properties of ACELs has been studied firstly. Then, the processing parameters of the paper-based ACELs such as electroless plated bottom electrode and spin-coated phosphor layer as a function of the humidity-sensitive characteristics are investigated. The sensing mechanism of the proposed sensor has been elucidated based on the Q~V analysis. The sensor exhibits an excellent linearity (R2=0.99965) within the humidity range from 20% to 90% relative humidity (RH) and shows excellent flexibility. We also demonstrate its potential application in postharvest preservation where the EL light is used for preservation and the humidity can be monitored simultaneously through the current.

Enhancement of Luminance in Powder Electroluminescent Devices by Substrates of Smooth and Transparent Cellulose Nanofiber Films

“…Because of this advantage, the powder EL devices, which can be fabricated by 3D printing [ 1 , 2 ], exhibit good mechanical durability, such as bending durability [ 3 ], flexibility [ 4 ], and stretchability [ 5 , 6 ]. They can also be used as sensors for ammonia [ 7 ], carbon dioxide [ 8 ], humidity [ 9 ], and temperature [ 10 ]. Unique functionalities, such as the self-recovery of their structure [ 11 , 12 , 13 ] and the generation of sound [ 14 , 15 , 16 ], have also been developed through the powder EL system.…”

Multifunctional Displays and Sensing Platforms for the Future: A Review on Flexible Alternating Current Electroluminescence Devices

“…Humidity sensor. Reproduced with permission from ref . Copyright 2019 Molecular Diversity Preservation International.…”

“…That means the ACEL device can respond well to temperature changes through EL intensity. He et al 135 reported a filter paperbased current humidity ACEL sensor. Due to the synergetic function of filter paper and ZnS:Cu, the sensor exhibits excellent linearity (R 2 = 0.99965) within humidity range from 20% to 90%.…”

Humidity-Sensing Properties of a BiOCl-Coated Quartz Crystal Microbalance

“…Thus, a large number of researchers are committed to developing high-performance sensors (e.g., accurate results, high sensitivity, excellent reliability, rapid response/recovery time, good repeatability, low cost, etc. ). − So far, depending on different working principles, humidity sensors are classified into resistive humidity sensors, − capacitive sensors, , optical fiber humidity sensors, , and bulk acoustic wave (BAW) humidity sensors. , Among them, quartz crystal microbalance (QCM), a typical BAW device, is becoming a research hotspot with advantages of high sensitivity, low cost, easy operation, and digital output. − …”