Picosecond ultrasonics in a single biological cell

Abstract

The picosecond ultrasonic technique has been developed during the last 20 years due to permanent interest in the study of mechanical properties of nano- and micro-layers made of metals and semiconductors used in solid state physics and microelectronics. The technique relies on generation, propagation and detection of ultra-short acoustic waves by femtosecond laser pulses. Important advantages of these techniques are the absence of direct contact to the sample and extremely high frequency range. In this presentation, the picosecond ultrasonics technique is applied to generate and detect acoustic waves with a frequency as high as 15 GHz in a single biological cell. Hypersound velocity and attenuation can thus be mapped in the cell with the small lateral resolution provided by optics, ie 1μm. In addition to single cell imaging, the sensitivity of the measurements to cell compressibility suggests promising perspectives in the field of biology. An application to the analysis of mouse cells grafting on biomaterials will illustrate the potentialities for quantitative evaluation of implants bio compatibility.