Passivated Porous Silicon Membranes and Their Application to Optical Biosensing

Area of Science:

• Materials Science
• Nanotechnology
• Biosensing

Background:

• Mesoporous silicon (PSi) membranes are promising for sensing applications.
• Standard fabrication methods often result in unstable PSi.
• Passivation is crucial for enhancing the stability and performance of PSi-based devices.

Purpose of the Study:

• To develop a robust fabrication method for stable mesoporous silicon membranes.
• To explore the use of atomic layer deposition (ALD) for passivating PSi membranes with various metal oxides.
• To evaluate the performance of these membranes in a biosensing application for bacterial detection.

Main Methods:

• Standard microfabrication techniques were employed to create PSi membranes.
• Atomic layer deposition (ALD) was used to deposit aluminium oxide (Al2O3), hafnium oxide (HfO2), and titanium oxide (TiO2) for passivation.
• Morphological, optical, and chemical characterization were performed.
• Stability tests and optical probing noise level determination were conducted.

Main Results:

• A robust fabrication method yielding stable PSi membranes was established.
• ALD passivation effectively protected the PSi membranes.
• The Al2O3-passivated membrane demonstrated selective optical detection of Bacillus cereus bacterial lysate.
• Detection of bacterial lysate at an initial concentration of 10^6 CFU/mL was achieved in under 10 minutes.

Conclusions:

• The developed fabrication method provides stable and reliable mesoporous silicon membranes.
• ALD passivation is an effective strategy for enhancing the durability of PSi.
• The Al2O3-passivated PSi membrane shows significant potential as a rapid and selective biosensor for bacterial detection.