High-performance humidity sensors utilizing dopamine biomolecule-coated gold nanoparticles

This study presents a simple process for producing resistance-based humidity sensors utilizing dopamine (DA)-coated gold nanoparticles (AuNPs) as the sensing material. Highly hydrophilic dopamine biomolecules are physically bonded to 4–6 nm AuNPs to enhance humidity sensing performance. Results show that the DA-coated AuNPs have good humidity sensing performance in the range of 20–90% R.H. The measured resistance response is more than 1900 times greater than sensors using the same AuNPs without a DA coating. The developed humidity sensor shows rapid response time for water adsorption (5 s) and desorption (10 s). Moreover, a 3-day long-term measurement at low medium and high humidity ranges also showed that the developed sensor has good stability. The method developed in this study provides a simple and inexpensive method to produce high-performance humidity sensors by using DA-coated AuNPs.