Laser Processed Hybrid Lead-Free Thin Films for SAW Sensors

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Acoustic wave devices offer sensitive platforms for gas detection.
• Barium strontium titanate (BST) is a piezoelectric material with tunable properties.
• Polyethylenimine (PEI) can enhance sensor sensitivity through surface modification.

Purpose of the Study:

• To investigate the interaction of gases with modified BST surfaces for gas sensor applications.
• To evaluate the performance of surface acoustic wave (SAW) devices incorporating PEI/BST heterostructures.
• To determine the effect of BST deposition conditions and strontium concentration on sensor response.

Main Methods:

• Thin films of BST were fabricated using pulsed laser deposition (PLD).
• PEI thin films were deposited using matrix assisted pulsed laser evaporation (MAPLE).
• Heterostructures were integrated into SAW devices with interdigital Au electrodes for frequency response measurements.

Main Results:

• SAW sensors exhibited frequency shifts upon exposure to N2, CO2, and O2 at room temperature.
• Optimal frequency shifts were observed for sensors with a strontium concentration (x) of 0.75.
• The BST50 polymer sensor demonstrated the most significant frequency shift for CO2 detection.

Conclusions:

• The deposition conditions and strontium content in BST significantly influence SAW gas sensor performance.
• PEI/BST heterostructures show promise for developing sensitive and selective gas sensors.
• The BST50/PEI combination is particularly effective for CO2 sensing applications.