Document Type



Doctor of Philosophy (PhD)


Electrical Engineering

First Advisor's Name

Dr. Shekhar Bhansali

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Dr. Nezih Pala

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Dr. Jean Andrian

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Dr. Bruce McCord

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Dr. Mubarak Mujawar

Fifth Advisor's Committee Title

Committee member


Nanoparticles, Plasma, SERS, electrodes, biosensing

Date of Defense



In this work, the effects of atmospheric plasma treatment on morphology, optical, and electrochemical properties of 10 ± 3nm spherical silver and gold nanoparticles (AgNPs and AuNPs) functionalized substrates were studied. The nanoparticles (NPs) were deposited on substrates by drop-casting, aerosol spray, and a low-temperature atmospheric plasma-assisted aerosol jet. The reduction in nanoparticle size was observed, which was explained by the redox reaction that occurs on the nanoparticle surface. This phenomenon was evident by the presence of AgO, Ag2O, and AuOx Raman peaks in the treated sample. The surface charge changed as a result of plasma treatment, as indicated by a significant change in the zeta potential from +25.1 ± 4 mV for the untreated AgNPs to −25.9 ± 6 mV after 15 minutes of plasma treatment and from -20.9 ± 4 mV to -43.9± 5 mV for AuNPs. Surface-enhanced Raman spectroscopy of the plasma-treated films was carried out with the fluorescent dye Rhodamine 6G, which showed a ~120-fold enhancement for AgNPs and ~95 fold for AuNPs in the signal intensity relative to the untreated substrates. This surface charge tuning during deposition led to the effective surface coverage with comparatively uniform NPs films as observed in Scanning Electron Microscopy, and Transmission Electron Microscopy images. This technique can be applied to a wide range of nanoparticle systems used in biosensing applications as substrates prepared by this method can serve as effective SERS substrates due to the cumulative effect of surface roughness, and size reduction.

The electrochemical performance of plasma-assisted NPs-modified microelectrodes was studied. These microelectrodes were fabricated using standard photolithography, Chrome/Gold evaporation, and lift-off techniques. These electrodes showed more enhancement in the electroactive surface area and improved inter-electrode variability than in other methods. Electrochemical Impedance spectroscopy results showed the improvement in the conductivity of plasma-assisted NPs functionalized electrodes. Cortisol was detected using self-assembled monolayer, and antibodies functionalized on plasma-assisted NP-modified electrodes, which showed increased sensitivity.

Previously Published In

  • A. Sonawane, P. Manickam, S. Bhansali, 2019. Stability of enzymatic biosensors for wearable applications. IEEE reviews in Biomedical Engineering 10, 174-186
  • A. Sonawane, M. A. Mujawar, S. Bhansali, 2019. Atmospheric Plasma Treatment Enhances the Biosensing Properties of Graphene Oxide-Silver Nanoparticle Composite. Journal of The Electrochemical Society 166 (9) B3084-B3090
  • P Manickam, V Kanagavel, A Sonawane, SP Thipperudraswamy, A Sonawane Electrochemical Systems for Healthcare Applications. Bioelectrochemical Interface Engineering, 385-409.
  • A. Sonawane, M. A. Mujawar, S. Bhansali, 2019. Cold Atmospheric Plasma Annealing of Plasmonic Silver Nanoparticles. ECS Transactions 88 (1), 197-201
  • A Sonawane, M Mujawar, S Bhansali, 2020. Plasma Assisted Control of Nanoparticle Distribution for Enhancing the Electrochemical Activity of Electrodes. 237th ECS Meeting with the 18th International Meeting.
  • A Sonawane, M Mujawar, S Bhansali, 2020. Effects of Cold Atmospheric Plasma Treatment on the Morphological and Optical Properties of Plasmonic Silver Nanoparticles. Nanotechnology Nanotechnology 31 365706 (11pp).

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License