A multi-purpose modular system for high-resolution microscopy at high hydrostatic pressure

TL;DR

This paper introduces a versatile modular high-pressure microscopy system capable of high-resolution imaging under various pressures and temperatures, demonstrated through multiple biological and physical applications.

Contribution

The authors present a novel modular system for high-resolution microscopy under high hydrostatic pressure, adaptable for diverse applications and capable of precise pressure and temperature control.

Findings

Effective pressure calibration using liquid crystal phase transition.

Successful imaging of bacteria growth at 50MPa.

Time-resolved imaging of colloidal phase transitions.

Abstract

We have developed a modular system for high-resolution microscopy at high hydrostatic pressure. The system consists of a pressurised cell of volume ~100 microlitres, a temperature controlled holder, a ram and a piston. We have made each of these components in several versions which can be interchanged to allow a wide range of applications. Here, we report two pressure cells with pressure ranges 0.1-700MPa and 0.1-100MPa, which can be combined with hollow or solid rams and pistons. Our system is designed to work with fluorescent samples (using a confocal or epifluorescence microscope), but also allows for transmitted light microscopy via the hollow ram and piston. The system allows precise control of pressure and temperature [-20-70C], as well as rapid pressure quenching. We demonstrate its performance and versatility with two applications: time-resolved imaging of colloidal phase transitions caused by pressure changes between 0.1MPa and 101MPa, and imaging the growth of Escherichia coli bacteria at 50MPa. We also show that the isotropic-nematic phase transition of pentyl-cyanobiphenyl (5CB) liquid crystal provides a simple, convenient and accurate method for calibrating pressure in the range 0.1-200MPa.