Meaning
Microscopic transducers manufactured using vapor deposition or lithography to measure temperature with minimal thermal mass. Thin film thermal sensors provide high speed response times because they do not significantly disturb the temperature field they are measuring. These devices typically use the temperature dependent resistance of a metal layer like platinum or nickel to generate a signal.
Surface Integration
Placement of these sensors directly on the current collectors or separators of a battery enables the mapping of internal conditions. Because they are only a few micrometers thick, thin film thermal sensors can be embedded inside a cell without affecting the mechanical stack pressure. This provides a level of detail on internal kinetics that is impossible to achieve with standard thermocouples.
The thin profile ensures that the sensor responds to temperature fluctuations in milliseconds, making them ideal for monitoring transient events like pulse discharge or internal shorting.
Precision Manufacturing
Fabrication involves precise control over the thickness and composition of the resistive layer. The durability of thin film thermal sensors in the harsh chemical environment of a battery electrolyte is a primary concern for long term monitoring. Specialized protective coatings are often applied to prevent corrosion and ensure the sensor lasts for the entire life of the cell.
Data Acquisition
Signals from these sensors are often low voltage and require high quality amplification and filtering. The use of thin film thermal sensors in research leads to the development of better safety standards and more accurate thermal models. They are increasingly being considered for high performance battery packs where safety margins are tight.
