Noninvasive holographic sensor system for measuring stiffness of soft micro samples

Area of Science:

• Cellular biomechanics
• Biomedical engineering
• Optics and photonics

Background:

• Accurate cell stiffness measurement is crucial for understanding disease progression, including cancer metastasis and tissue mechanics.
• Conventional methods like atomic force microscopy and optical stretching have limitations such as invasiveness, low throughput, and complex sample preparation, hindering their use in dynamic biological settings.

Purpose of the Study:

• To introduce a noninvasive holographic sensor system for evaluating the stiffness of soft microscale samples.
• To provide a label-free, high-throughput method for assessing mechanical properties while maintaining sample integrity.

Main Methods:

• Integration of holographic imaging with acoustic stimulation using an off-axis Mach-Zehnder interferometer and bulk acoustic waves.
• Validation using polyacrylamide beads engineered to mimic cellular stiffness.
• Implementation of a structured imaging approach and calibration strategy to minimize spatial variation errors.

Main Results:

• Minimized measurement errors and improved uniformity across sample regions through advanced imaging and calibration.
• Demonstrated stable and repeatable stiffness measurements, unaffected by sample size variations.
• Confirmed system robustness and reliability through extensive repeatability tests.

Conclusions:

• The developed holographic sensor system shows significant potential for advancing cell biomechanics research and cancer diagnostics.
• This noninvasive, high-throughput method offers a valuable alternative for mechanical property assessment in biological samples.
• The system contributes to improved characterization of cellular stiffness in various biomedical applications.