Bonding of diatom frustules and Si substrates assisted by hydrofluoric acid

Abstract

Diatoms, with hierarchical micro/nanoscale porous silica structures, have promising application in micro-nanotechnology especially biochemical sensing. In order to explore their potential and prepare diatom based substrates for biochemical sensor application, a fabrication technology for bonding diatom frustules and Si substrates was developed. The bonding process was carried out at 75 °C and assisted by hydrofluoric acid (HF). The bonding mechanism was discussed and several bonding conditions were adjusted to keep the morphological integrity of diatom frustules after bonding. The bonding pressure was optimized from 2.0 × 10⁴ Pa to 3.0 × 10⁴ Pa and the HF concentration from 0.4% to 0.6%. And the optimal shear bonding strength achieved was 0.72 MPa. In addition, bonded diatom frustules were further used as masks to obtain nano gold pillar arrays for surface-enhanced Raman scattering (SERS) detection.