Inkjet-printed plasma-functionalized polymer-based capacitive sensor for PAHs

The inkjet-printing technology is utilized to foster conducting layers, interconnections, and other features on different substrates of which its success greatly depends on the surface properties of the substrates. In the present work, we reported the use of low-temperature plasma (LTP) to assist in tailoring the surface properties of polyethylene terephthalate (PET). This facilitated the inkjet printing of a capacitive electrode sensor design using silver nano-ink (AgNI) for polycyclic aromatic hydrocarbons (PAHs). PAHs are ubiquitous environmental pol-lutants that are of great health concern. We have sifted methyl methacrylate (MMA), N-vinylpyrrolidone (VP), and oxygen (O2) as plasma fed-gases for improving the adhesion of printed AgNI on PET. We observed improved surface hydrophilicity of the plasma-treated PET (p-PET). This was evidenced by the decrease in water contact angle (WCA). The change in surface chemistry with plasma treatment was assessed using X-ray Photoelectron spectroscopy (XPS). Atomic Force Microscopy (AFM) was employed in determining the nanoscale surface roughness of PET. We then fabricated the capacitive sensor using AgNI to quantitatively sense the PAH from aqueous media. This sensor was subsequently characterized using Scanning Electron Microscopy (SEM) and Keyence 3D imaging. The capacitance values have shown a linear response with increased PAH concentration. The sensor design exhibits a high sensitivity for PAH concentrations up to 0.05 ng/mL. Ultimately, these results have demonstrated the potential of this polymer device for pollutant sensing applications.