@inproceedings{6ef10460196446aab750492292e58d46,
title = "Nano-rheology of hydrogels using direct drive force modulation atomic force microscopy",
abstract = "Hydrogels are widely used soft materials in cartilage tribology, among other applications. We present a magnetic force-based direct drive modulation method to measure local nano-rheological properties of Polyacrylamide hydrogels across a broad frequency range (10 Hz - 2 kHz) using colloid-attached AFM probes in liquid. The frequency bandwidth was extended to lower frequencies (upto 0.1 Hz) by acquiring slow force-displacement which show loading-direction mechanical behavior dependence: approach curves showed Hertzian while retraction curves fit JKR model. Using small amplitude modulation at faster rates, the load dependence of the storage stiffness transitioned from Hertzian to a dynamic punch-type model, indicating significant influence of material dissipation coupled with adhesion. The study highlights possible transitions in the probe-material contact mechanical behavior of soft matter especially when the applied strain rates and the material relaxation rates become comparable.",
keywords = "Dynamic punch-model, Hydrogels, Nano-rheology, Nanoscale viscoelastic force spectroscopy, Polyacrylamide",
author = "Nalam, \{P. C.\} and N. Gosvami and M. Caporizzo and Composta, \{R. J.\} and Carpick, \{R. W.\}",
year = "2016",
language = "English",
series = "Society of Tribologists and Lubrication Engineers Annual Meeting and Exhibition 2016",
publisher = "Society of Tribologists and Lubrication Engineers",
pages = "308--310",
booktitle = "Society of Tribologists and Lubrication Engineers Annual Meeting and Exhibition 2016",
address = "United States",
note = "71st Society of Tribologists and Lubrication Engineers Annual Meeting and Exhibition 2016 ; Conference date: 15-05-2016 Through 19-05-2016",
}