In-Plane Mode Encased Cantilevers for Cancer Cell Detection in Liquid

We report on the first experimental demonstration of real-time cancer cell detection in liquid using in-plane mode encased cantilever resonators. Facilitated by a hydrophobic parylene shell and in-plane vibrational mode, high-quality-factor resonance in liquid is achieved due to the minimized viscous damping. With on-chip all-electrical excitation and readout technique, the in-plane vibrations of the cantilevers are measured to be ~510-560 kHz with quality (Q) factors ~1000 in air and ~100 in liquid. We estimate the device mass responsivity to single microparticle loading to be ~0.7Hz/pg. Integrating the device chip with a time-lapse imaging system further allows us to detect single breast cancer cells cultured on the cantilevers. Cell attachment, growth and apoptosis processes can be inferred from the close-loop frequency changes while morphological changes are simultaneously observed in the optical/fluorescent images. Such in-plane mode encased cantilevers hold promise for biophysical studies of cells and molecular interactions in liquid.