Development of Dental Implantable Thin Film Temperature Sensor

Objectives: The objective of this project is to develop a real-time thin film temperature sensor that can be embedded to dental implant system for early diagnosis of dental implant failures including peri-implantitis.
Methods: The thin film temperature sensor was designed and fabricated using microelectromechanical systems (MEMS) at National Institute of Standards and Technology (NIST). Microfabrication was performed on a 4-inch silicon wafer to pattern 3μm-width platinum resistance temperature detectors (RTD), and gold interconnection lines and pads on the bottom polyimide thin film. The interconnection lines were covered with polyimide film for insulation. To determine its performance, the linearity, sensitivity, and response time were measured. We also performed stability test by immersing the sensor in mouthwash and biocompatibility test by culturing with murine oral cells.
Results: The performance tests of the thin film temperature sensor showed that: (1) 8-9μm sensor had high flexibility without showing stress-associated curling or polymer degradation. (2) 3μm RTD had an accurate dimensional pattern with clean edges and well-connected lines. (3) The sensor was successfully placed inside a dental implant by wrapping its abutment wing with intact electronic sensing properties. The sensor reported excellent linear performance between 0^°C-100^°C with high sensitivity and quick response time. For chemical stability, no statistical difference was observed between before and after immersion in mouthwash using optical images and Temperature Coefficient of Resistance (TCR) values. Additionally, no statistical difference was observed from cell culture by quantifying cell attachment with or without sensors for 5 days.
Conclusions: Using microfabrication process, we have successfully developed a polyimide-based thin film temperature sensor that can be incorporated into dental implants. Importantly, its linear RTD performance showed at least similar or better than that of conventional RTD. Our oral sensor and its fabrication process can be applied to other biomedical sensors that monitor and detect inflammatory responses.