Controlled integration of features
that enhance the analytical performance of a sensor chip is a challenging
task in the development of paper sensors. A critical issue in the
fabrication of low-cost biosensor chips is the activation of the device
surface in a reliable and controllable manner compatible with large-scale
production. Here, we report stable, well-adherent, and repeatable
site-selective deposition of bioreactive amine functionalities and
biorepellant polyethylene glycol-like (PEG) functionalities on paper
sensors by aerosol-assisted, atmospheric-pressure, plasma-enhanced
chemical vapor deposition. This approach requires only 20 s of deposition
time, compared to previous reports on cellulose functionalization,
which takes hours. A detailed analysis of the near-edge X-ray absorption
fine structure (NEXAFS) and its sensitivity to the local electronic
structure of the carbon and nitrogen functionalities. σ*, π*,
and Rydberg transitions in C and N K-edges are presented. Application
of the plasma-processed paper sensors in DNA detection is also demonstrated.