Pulsed-laser-activated impulse response encoder (PLAIRE): detection of core–shell structure of biomimetic micro gel-sphere

Abstract

Mechanical properties of biological cells and tissues contain important information for further understanding of their function. To estimate mechanical properties of micro-sized biological objects, we developed a system: pulsed-laser-activated impulse response encoder (PLAIRE). In the PLAIRE, femtosecond laser-induced impulsive force is applied to excite elastic waves on a micro-biological object and the excited elastic waves are detected by atomic force microscopy (AFM) as cantilever’s oscillations. In this work, PLAIRE is applied to estimate Young’s moduli of calcium alginate (CaAlg) micro gel-sphere as a biomimetic object. The Young’s modulus calculated from the propagating velocity of surface elastic waves (Rayleigh waves) are 3.7 times larger than that of the entire sphere measured with AFM force curve. The results indicate PLAIRE specifically detects surface mechanical properties of CaAlg which is harder than the inside.