Acoustophoretic force-based compressibility measurement of cancer cells having different metastatic potential

Mechanical properties of cells such as compressibility are regarded to be different as cancer cells progress into metastatic state. Traditional methods for measuring mechanical properties of single cells such as AFM and micropipette aspiration, require labor-intensive procedures and can cause damage to cells due to direct contact, thus unsuitable for high-throughput measurement. Acoustophoretic force exerted on particles under acoustic-standing-waves depends on the particle and medium's vibro-acoustic properties. Thus, cells with different mechanical properties show different mobility under acoustic resonant field which can be analyzed to decipher the mechanical properties of cells. Here we present a high-throughput, single-cell-resolution, cell compressibility measurement approach based on acoustic-standing-wave-induced force, and the finding that head and neck cancer cells having different metastatic capacities show noticeable differences in compressibility. The acoustophoresis chip has a straight flow channel with a piezoelectric transducer attached at the bottom. Trajectories of moving cells in the channel under acoustic standing wave excitation in the absence of flow are recorded. By using a microfluidic acoustophoretic model, the simulated trajectories of cells are calculated. The mechanical properties of cells are estimated by fitting the experimental and simulated trajectories thereby. Cells with highest metastatic capacity showed highest compressibility, consistent with previously reported clinical observations.