Sealed and temperature-controlled sample cell for inverted and confocal microscopes and fluorescence correlation spectroscopy

Precise temperature control of sample environments plays a key role while exploring biological systems or temperature-sensitive materials. We have developed a sample cell for inverted microscopes, which allows a temperature accuracy of ±0.05 K in a temperature range of 5 to 65 °C, with an absolute precession of ±0.1 K. Our sample cell is developed for requirements of single-molecule experiments, which comprises easy-to-clean and well-sealed devices to prevent solvent evaporation. The applied control algorithm permits a tunable independent setting of heat and cooling behavior and allows the application on microscopes without any objective heating. For measuring precise and absolute diffusion coefficients with two-focus fluorescence correlation spectroscopy, the exact control of the sample temperature is essential. We performed diffusion measurements of TetraSpeck 100-nm fluorescent latex particles and of temperature-sensitive microgels in aqueous solutions to demonstrate the excellent temperature stability and reproducibility of the device.