PODS-covered PDA film based formaldehyde sensor for avoiding humidity false response

•For the first time, PODS was combined with PDA as a composite material.•Designing PODS-covered PDA film based QCM formaldehyde sensor which can avoid humidity false response.•The sensor still maintain good response performance to detect formaldehyde.•The sensor displayed good stability, because PODS possesses self-cleaning ability. To avoid false response caused by increase of environmental humidity is important for hydrophilic polydopamine (PDA) based QCM formaldehyde sensor. In order to achieve this purpose, superhydrophobic polymerized n-octadecylsiloxane (PODS) nanostructure is used to cover the surface of PDA film to prevent false response from happening. Compared with pristine PDA based QCM sensor, the sensor based on PODS-PDA composite sensing material shows satisfactory performance on avoiding false response and long-term stable formaldehyde sensing properties. This novel strategy offers a new method to reduce probability of false response resulted from humidity change.