Thermal Monitoring: Raman Spectrometer System for Remote Measurement of Cellular Temperature on a Microscopic Scale

A simple setup was demonstrated for remote temperature monitoring of water, water-based media, and cells on a microscopic scale. The technique relies on recording changes in the shape of a stretching band of the hydroxyl group in liquid water at 3,100-3,700 cm^-1. Rather than direct measurements in the near-infrared (IR), a simple Raman spectrometer setup was realized. The measured Raman shifts were observed at near optical wavelengths using an inverted microscope with standard objectives in contrast to costly near-IR elements. This allowed for simultaneous visible inspection through the same optical path. An inexpensive 671-nm diode pump laser (<100 mW), standard dichroic and lowpass filters, and a commercial 600-1,000 nm spectrometer complete the instrument.