Hydrofluoric acid-assisted bonding of diatoms with SiO ₂-based substrates for microsystem application

Diatom, with delicate three-dimensional porous structures and texture, has a promising application in micro-nanotechnology especially biosensing. In order to achieve a diatom-based compound substrate, a fabrication technique is developed for hydrofluoric acid (HF) bonding of diatom with SiO ₂-based substrate at a temperature as low as 80 °C. The bonding conditions are optimized with various HF concentrations and applied pressure. The optimized HF concentration is found to be in the range of 0.8% to 1.2% and applied pressure is from 0.4.0 MPa to 0.6.0 MPa. The morphological integrity and nano-microscale substructures of the diatoms after bonding are characterized. The bonding strength is approximately 0.435 MPa.