A simple prototype for assessing plant cold hardiness with differential thermal analysis

Differential thermal analysis (DTA) is a laboratory technique used to assess cold tolerance of plant tissue by detecting low temperature exotherms released when intracellular water freezes and cells are damaged. Measurements are made by placing samples on thermoelectric modules (TEMs) in a programmable freezer, slowly reducing the temperature, and detecting the latent heat of fusion released when intracellular water undergoes a phase change from liquid to solid. TEMs are solid-state Peltier devices that are commonly used for heating or cooling of electronics depending on the direction of the applied electrical current. In their quiescent state, they are very effective heat flux sensors that can be used to detect minute changes in temperature. Configurations that multiplex many TEMs for DTA have been used for several decades to assess cold tolerance, but the details of how they are constructed and programmed are limited. Here I present a simple prototype for assessing plant cold hardiness with DTA using a legacy datalogger and TEMs as a proof of concept. By using single-ended voltage measurements to monitor the TEMs, the number of samples which can be monitored can be maximized, thereby reducing the need for multiplexers. This prototype demonstrates that DTA can be accessible to researchers using basic dataloggers.