Daily writing carbon ink: Novel application on humidity sensor with wide detection range, low detection limit and high detection resolution

Abstract

Abstract For a long time, the application of the daily writing carbon ink is mainly reflected on writing and painting, and rarely used in electronic field. Herein, we analyzed the physical and chemical properties of the daily writing carbon ink. Characterization results show that the daily writing carbon ink is mainly composed of carbon nanoparticles, and has good hydrophilicity and very stable dispersion. Further, the humidity sensor was fabricated using daily writing carbon ink and its humidity sensing performances were investigated at room temperature (20 °C). The testing results show that the resistance of the humidity sensor increases with the increase of relative humidity (RH), showing a positive humidity sensitive characteristic. Compared with most of the reported humidity sensors, the carbon ink humidity sensor has better humidity sensing performances on wide detection range (2 − 95 % RH), low detection limit (2% RH) and high detection resolution (1% RH). Finally, the positive humidity sensitive characteristic of the humidity sensor is analyzed using electron tunneling effect (blocking of water molecular membrane). This work not only demonstrates a facile and low-cost way to realize high performance humidity sensor, but also provides a pathway for the research of humidity sensor with positive response characteristic.