Nano-measuring living cell surface by AFM

An atomic force microscope (AFM) is a powerful tool for investigating soft materials in liquid environments. We developed a newly designed AFM, which employs a fiber-optic interferometer and a low coherence laser such as a super-luminescence diode. The advantage of this AFM is that this AFM is set up on a conventional optical microscope without blocking a light path for obtaining optical images and that the AFM does not suffer from a stray light of the fiber-optics, which is usually inevitable. It was demonstrated that the AFM could measure the small deflection of the AFM cantilever. Moreover, we developed a technique that precisely measures the contact point between the soft cell surfaces and an AFM tip. The result was that the spectrum of the thermally vibrated cantilever was drastically decreased when the tip contacted the surface, indicating that the method is useful for determining the contact of the tip-soft materials such as living cells in liquids.