Effects of ion bombardment with reactive gas environment on adhesion of Au films to Parylene C film

The dual role of Parylene C in chemical sensing: Acting as an encapsulant and as a sensing membrane for pH monitoring applications

“…6b, with the O 1s core level at ~532.5 eV. The peak at ~289 eV is most likely from carboxyl groups (C=O), which also agrees well with previous studies [13,14]. The sample treated at 400 W/10 min has been greatly functionalized and shows significant surface oxidation (including the possibility of pinholes in the film by a concurrent etching process).…”

“…Conformally and selectively plasma exposed (400 W/10 min) Parylene sensors demonstrate lower drift than untreated Parylene, exhibiting the largest drift rates in pH 4 solution (22.07 and 20.19 mV/h respectively), whereas their drift rates for pH 7 and 10 are lower than 10 mV/h ( Table 1). The large H + concentration in pH 4 solution is likely to initiate massive reactions between the ions and the free carboxyl groups present on the surface of treated Parylene, as stated previously [13,14].…”

“…3d depicts the I D -V GS curves of selectively treated sensors tested 45 and 90 days after plasma exposure respectively, indicating that H + sensitivity is slightly lower in the long-term, nevertheless, it still persists. The induced hydrophilicity of oxygen plasma treated Parylene C has been previously attributed to the formation of free carboxyl groups that are prone to bind with hydrophilic molecules [13,14]. The reactions that take place between the hydrophilic groups result in a diminished number of free binding sites on the film surface.…”

“…Many research efforts have been realized to alter the hydrophobic properties of Parylene C with particular focus on the biomedical applications. Oxygen plasma treatment has been previously employed to effectively modify the surface properties of such films [13,14], with special emphasis on utilizing the material as a cell culture substrate [15,16]. In other studies, Parylene has been employed for patterning cells and proteins either by enhancing attachment of proteins after UV exposure [17], or as a peel-off stencil [18].…”

A 2D approach to surface-tension-confined fluidics on parylene C

“…Specically, plasma provoked hydrophilicity is caused by the bonding of oxygen-based chemical groups onto the polymer surface, such as hydroxyls, aldehydes, carbonyls or carboxyls, which contributes to increase the surface energy. [45][46][47] Seong et al and Hoshino et al 47,48 conrmed this feature with their X-ray photoelectron spectroscopy analysis performed on parylene C samples, revealing that a larger amount of oxygen and a smaller one of carbon atoms follows oxygen plasma treatments. Moreover, during the plasma process also the nanotexturing of the surface is induced 14 via physical interaction with reactive ions, achieving surface superhydrophilicity according to Wenzel's wettability model.…”