Poster Presentation: Yilmaz Arin Manav

ABSTRACT

GHz Ultrasound for Microscale Mapping of Hydration Induced Stiffness Changes

Yilmaz Arin Manav, Eda Ozyilmaz, Benyamin Davaji

Aging triggers significant mechanical changes in the body that can manifest various conditions. These mechanical changes that most notably transpire in the skin and microcirculation lead to conditions ranging from edema, fibrosis, and varicose veins on a tissue level to loss of ECM elasticity and integrity on a cellular level. They arise from reasons such as aging-related reduction in collagen production, an increase in vascular permeability, as well as long-term oxidative stress and inflammation. [1] [2] As the effects of these factors can start out very localized, it becomes important to bridge the gap between the micro-scale localized mechanical changes and the tissue-level elastic property changes by quantitative measurements. The standard measurement methods range from optical (Brillouin microscopy) [3] and mechanical (high frequency ultrasound, atomic force microscopy) methods [4] to histological analysis. While these methods work on their respective size scales, this requires multiple methods to tie localized findings to tissue-level elasticity changes.  Measurement of both micro-scale localized, and tissue-level mechanical changes require a high-resolution method that has a large field of measurement. Our GHz ultrasound pulse-echo reflectometry measurement scheme employs a high axial and lateral resolution ultrasound transducer array that can measure micron-scale localized changes in mechanical properties (λ~0.8µm in water) in an area of 6.4mm x 6.4mm (FoV) for tissue scale measurements due to its GHz frequency of operation and 128 x 128 element ultrasound array that consists of transducers with 50µm pitch. [5] It functions by transmitting GHz frequency pulses that can be coupled to micron-scale structures and receiving echo signals to compute the acoustic reflection coefficient of the samples. [6] In this study, we display that GHz ultrasound can map the hydration induced localized stiffness changes for tissue scale hydrogel samples, in-real time and non-invasively.

References:

[1] Oakley, Ryan, and Binu Tharakan. “Vascular hyperpermeability and aging.” Aging and disease vol. 5,2 114-25. 1 Apr. 2014, doi:10.14336/AD.2014.0500114

[2] Selman, Moisés, and Annie Pardo. “Fibroageing: An ageing pathological feature driven by dysregulated extracellular matrix-cell mechanobiology.” Ageing research reviews vol. 70 (2021): 101393. doi:10.1016/j.arr.2021.101393

[3] Blackburn, Brecken J., et al. “A review of structural and biomechanical changes in the cornea in aging, disease, and photochemical crosslinking.” Frontiers in Bioengineering and Biotechnology, vol. 7, 29 Mar. 2019, https://doi.org/10.3389/fbioe.2019.00066.

[4] Vergilio, Mariane Massufero et al. “Characterization of skin aging through high-frequency ultrasound imaging as a technique for evaluating the effectiveness of anti-aging products and procedures: A review.” Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI) vol. 27,5 (2021): 966-973. doi:10.1111/srt.13033

[5] Y. A. Manav et al., “Towards GHz Ultrasound Enabled Noninvasive Hydrogel Metrology for Mechanobiology,” 2024 IEEE 37th International Conference on Micro Electro Mechanical Systems (MEMS), Austin, TX, USA, 2024, pp. 276-279, doi: 10.1109/MEMS58180.2024.10439458.

[6] Y. A. Manav, A. Piasecki, A. Lal, D. Woods and B. Davaji, “GHz Ultrasound for Quantitative Oocyte Mechanobiology,” 2025 23rd International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers), Orlando, FL, USA, 2025, pp. 526-529, doi: 10.1109/Transducers61432.2025.11110996.