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. Author manuscript; available in PMC: 2018 Mar 22.
Published in final edited form as: Nat Photonics. 2017 May 15;11:352–355. doi: 10.1038/nphoton.2017.74

Figure 3. Acoustic frequency detection.

Figure 3

a, Left: scheme showing an AFM tip acting (oscillating) as an acoustic source nearby a NPsensor. Right: example of a force mapping image (~300 pN force) that was used to locate a NPsensor and then the AFM tip was moved away to generate the acoustic wave. The double-headed arrow shows the movement of the AFM tip up and down to generate the acoustic wave. b, Fourier transformations of the NPsensor scattering intensity after oscillating the AFM tip at two different frequencies (1 and 2 Hz). c, Top left: cross-sectional side view of the microfluidic chamber used to house the NOFT and cardiomyocyte cell cluster. The UV laser was focused through the quartz cover onto the NOFT without illuminating the cells, and scattering signals were collected back through a top-mounted microscope objective (pictured on the right). Bottom left: optical image of a sample containing the 3 mm× 3 mm× 250 μm cardiomyocyte cell cluster (black arrow) that was placed ~100 μm away from the NOFT in the microfluidic chamber. d, Fourier transforms taken from the end facet of the NOFT with and without cardiomyocytes.