Gold Nanoparticles Encapsulated in Pressure-Deformable Alginate Hydrogel Microspheres as Sensors for Pressure Sensing

The ability to sense mechanical pressure is essential for various biological processes. Despite the importance, sensing tissue pressure is still challenging due to the lack of detecting techniques and the limited accessibility of sensors to the tissue. Herein, we propose a unique plasmonic microsensor based on nano-optomechanical transducers for sensing of pressure in tissues. The microsensor is constructed by densely encapsulating well-distributed gold nanoparticles (GNPs) in pressure-deformable alginate hydrogel microspheres. The size of microgel shrinks under the compression of environmental pressure, decreasing the distance between the embedded GNPs and increasing the GNPs’ plasmonic coupling, which further leads to the change of the optical signal including light absorption, scattering, and photoacoustic signal. By combination of photoacoustic imaging, the pressure of different tissues was successfully sensed by the plasmonic microsensor, providing a promising platform to sense mechanical pressure.