Time-Resolved Mechanical Spectroscopy of Soft Materials via Optimally Windowed Chirps

Abstract

The ability to measure the bulk dynamic behavior of soft materials with combined time- and frequency-resolution is instrumental for improving our fundamental understanding of connections between the microstructural dynamics and the macroscopic mechanical response. Current state-of-the-art techniques are often limited by a compromise between resolution in the time and frequency domain, mainly due to the use of elementary input signals that have not been designed for fast time-evolving systems such as materials undergoing gelation, curing or self-healing. In this work, we develop an optimized and robust excitation signal for time-resolved mechanical spectroscopy through the introduction of joint frequency- and amplitude-modulated exponential chirps. Inspired by the biosonar signals of bats and dolphins, we optimize the signal profile to maximize the signal-to-noise ratio while minimizing spectral leakage with a carefully-designed modulation of the envelope of the chirp. A combined experimental and numerical investigation reveals that there exists an optimal range of window profiles that minimizes the error with respect to standard single frequency sweep methods. The minimum error is set by the noise floor of the instrument, suggesting that the accuracy of an optimally windowed chirp signal is directly comparable to that achievable with a standard frequency sweep, while the acquisition time can be reduced by up to two orders of magnitude, for comparable spectral content. Finally, we demonstrate the ability of this optimized signal to provide time- and frequency-resolved rheometric data by studying the fast gelation process of an acid-induced protein gel. The use of optimally windowed chirps enables a robust rheological characterization of a wide range of soft materials undergoing rapid mutation and has the potential to become an invaluable tool for researchers across different disciplines.

References in corpus (10)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• Universal Robotic Gripper based on the Jamming of Granular Material
• Colloidal Gels: Equilibrium and Non-Equilibrium Routes
• Time Resolved Correlation measurements of temporally heterogeneous dynamics
• Creep and Fracture of a Protein Gel under Stress
• Ultrafast ultrasonic imaging coupled to rheometry: principle and illustration
• Differential Dynamic Microscopy microrheology of soft materials: a tracking-free determination of the frequency-dependent loss and storage moduli
• Nonlinear viscoelasticity and generalized failure criterion for polymer gels
• Large-scale analysis of frequency modulation in birdsong databases
• Local Oscillatory Rheology from Echography

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• Thixotropic spectra and Ashby-style charts for thixotropy
• Critical-like gelation dynamics in cellulose nanocrystal suspensions
• High-frequency Optimally Windowed Chirp rheometry for rapidly evolving viscoelastic materials: application to a crosslinking thermoset
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• Mastering Rheology: A Strategic and practical guide for empowering all users
• ShearView: A Compact Stress- and Strain-Controlled Rheometer for Integrated Rheo-microscopy
• Slow dynamics and time-composition superposition in gels of cellulose nanocrystals