Polymer resonators sensors for detection of sphingolipid gel/fluid phase transition and melting temperature measurement

Abstract

This work describes a low-cost biophotonic sensor shaped by way of cheap processes as hybrid silicon/silica/polymer resonators able to detect biological molecule gel/fluid phase transition as lipids at very low concentration (sphingomyelin). The photonic structure is composed of specific amplified deep UV photoresist-polymer waveguides coupled by a sub-wavelength gap with racetrack microresonators allowing a low temperature-dependent operation ranging from 16 to 42°C. The temperature dependent wavelength shift and the thermo-optic coefficient characterizing the quantified resonances and opto-geometric properties of the device have been evaluated, highlighting an enough low thermal features of the whole system for such application. With an appropriate vesicle lipid deposition process specific in biology associated to an apt experimental bio-thermo-photonic protocol (made of serial optical resonance spectra acquisitions with statistical treatments), the dynamic evolution of the sphingomyelin lipid phase transition was assessed: then, the ability to detect their own gel/fluid transition phase and melting temperature has been demonstrated with a mass product factor 107 lower than that of more conventional methods The equilibrium of the regime of the resonators was highlighted as being broken by the dynamic of the sphingomyelin and its own phase transition prior relevant detection.