Freeze-drying, also known as lyophilization, is a dehydration process that removes water by sublimation to preserve perishable materials or to make materials more easily transportable. During the freeze-drying process, temperature uniformity inside of the freeze-dryer is crucial to ensure process efficiency. Currently, during this process, vials undergo the sublimation process at different rates inside of the chamber. Scientists at PSI have acknowledged this flaw in the freeze-drying process and are developing a TDLAS-based sensor cap to help observe this issue. The PSI-developed sensor is predicted to help improve the freeze-drying cycle by applying the knowledge gathered from the process heterogeneity measurements via the device.