Wafer-Scale Fabrication and Transfer of Porous Silicon Films as Flexible Nanomaterials for Sensing Application

Abstract

Flexible sensors are highly advantageous for integration in portable and wearable devices. In this work, we propose and validate a simple strategy to achieve whole wafer-size flexible SERS substrate via a one-step metal-assisted chemical etching (MACE). A pre-patterning Si wafer allows for PSi structures to form in tens of microns areas, and thus enables easy detachment of PSi film pieces from bulk Si substrates. The morphology, porosity, and pore size of PS films can be precisely controlled by varying the etchant concentration, which shows obvious effects on film integrity and wettability. The cracks and self-peeling of Psi films can be achieved by the drying conditions after MACE, enabling transfer of Psi films from Si wafer to any substrates, while maintaining their original properties and vertical alignment. After coating with a thin layer of silver (Ag), the rigid and flexible PSi films before and after transfer both show obvious surface-enhanced Raman scattering (SERS) effect. Moreover, flexible PSi films SERS substrates have been demonstrated with high sensitivity (down to 2.6 × 10−9 g/cm2) for detection of methyl parathion (MPT) residues on a curved apple surface. Such a method provides us with quick and high throughput fabrication of nanostructured materials for sensing, catalysis, and electro-optical applications.

A Graphene-Coated Silicon Wafer Plate Improves the Sensitivity and Reproducibility of MALDI-TOF MS Analysis of Proteins

“…The graphene films produced homogeneous sample spots that generated highly reproducible signals for small molecules, such as peptides, lipids, and drugs. For several decades, silicon wafers have been employed in the semiconductor industry because of their effectiveness in enabling the deposition of organic and inorganic materials as thin films on their surface. , Because silicon wafers have lower surface roughness (<5 nm) than polished SUS plates, they can be considered as a promising source of plate base with both excellent flatness and the ability to attach graphene films.…”