Thin Film Sensors

Sensor Component

The functional structure of the device consists of a substrate, a protective barrier layer, an active sensing element and electrical contacts. In thin film sensors, the active element is typically a patterned metal or metal-oxide layer that changes its electrical properties in response to environmental variations. The thinness of the active layer ensures that the thermal and mechanical response is nearly instantaneous, making these devices ideal for dynamic measurements.

Material Stability

Operating at high temperatures exposes the metallic and dielectric layers to thermodynamic forces that can trigger degradation. Maintaining the structural integrity of thin film sensors requires careful selection of substrate and metallization materials to match their thermal expansion coefficients. Interdiffusion between layers is minimized by incorporating diffusion barriers, which prevent the degradation of the active sensing path and ensure long-term stability.

Performance Evaluation

Characterization under simulated field conditions is required to verify the drift and response time of the microfabricated device. The testing of thin film sensors involves exposing them to cyclic thermal and mechanical stresses while monitoring their electrical output. The collected data allow engineers to calculate the drift rate and the sensor’s lifespan, which are critical parameters for qualifying the sensor for industrial or aerospace applications.

By conducting these tests across a range of gas compositions and humidity levels, the evaluation also determines the cross-sensitivity of the sensor, ensuring that it remains selective to the primary target parameter.