Substrate-dependent thermal sensing using silver nanoparticles synthesized via laser ablation in solution.

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Silver nanoparticles (Ag NPs) possess unique properties valuable for sensing applications.
• Traditional synthesis methods like Laser Ablation Synthesis in Solution (LASiS) often yield broad size distributions, limiting tailored applications.
• Substrate interactions can significantly influence the functional properties of nanomaterials.

Purpose of the Study:

• To investigate the substrate-dependent electrical response of Ag NPs.
• To optimize Ag NP synthesis for narrow size distribution.
• To explore the potential for flexible temperature sensing technologies.

Main Methods:

• Synthesized Ag NPs using optimized Laser Ablation Synthesis in Solution (LASiS) with a 5W, 1064 nm DPSS laser in deionized water.
• Characterized Ag NPs size distribution (10-110 nm) using FESEM and TEM.
• Deposited Ag NPs on glass and fibrous paper substrates and measured their temperature-resistance behavior.
• Analyzed substrate-induced material changes using Thermogravimetric Analysis (TGA).

Main Results:

• Achieved high concentration (~128 mg/L) of spherical Ag NPs with a narrow size distribution.
• Observed contrasting temperature-resistance behaviors: positive TCR on glass and negative TCR (NTCR) on fibrous paper.
• TGA analysis indicated Ag2O formation on the paper substrate, likely due to heat treatment and substrate interaction.
• Hypothesized that Ag2O, a p-type semiconductor, contributed to the observed NTCR effect.

Conclusions:

• Controlled synthesis of Ag NPs with narrow size distribution is achievable.
• The substrate plays a critical role in determining the functional properties of Ag NP systems.
• The observed NTCR effect on paper opens avenues for novel flexible temperature sensors.