Projects now available in the group:

Tooth inspection
using THz radiation

General description

Terahertz (THz) radiation is a particular kind of light, situated between microwaves and infrared, which penetrates many objects that visible and infrared light don’t. In that sense, it is like x-rays, although it generally gives a much sharper contrast and doesn’t have the ionizing, dangerous, properties of x-rays. In addition, its common form of generation and detection occurs in the time-domain, opposite to the frequency domain of most optical technologies. This allows robust determination of a particularly vast material parameter space. Hence, THz spectroscopy is seen as a promising enabler of applications that will promote humanity to its autonomous future, including of smart cities, smart farming, tele medicine, etc.

In the last five years, first real-life applications for THz spectroscopy have been found and have been tested for implementation. These applications range from quality control of drying paint layers on automotive car bodies, to inspection of paper sheets during their production and determination of charge carrier densities in semiconductors for high-power applications such as locomotives. Despite the success of these applications, our aim is to push the technology to sensing applications which are of broader use, and particularly in the medical field, such as to foster a smart future as mentioned above.

Students task description

The project goal relates to the first examination of teeth using THz spectroscopy. Until now, only (dried) thin tooth slabs have been measured. However, in order for this application to become a breakthrough for dentists, entire teeth and molars have to be diagnosed. As mentioned above, THz radiation is expected to penetrate entire teeth, and particularly to give a more insightful picture of their health status than x-rays.

To this end, a newly acquired THz time-domain spectrometer, being among the bests of its kind, and a specially designed measurement head, is available for this work. The measurement head is robot-mounted, such that the tooth can be inspected from all directions. Collaborations with hospitals in the region are foreseen. The project comprehends the following work packages:

• adapting a Python-based script to control the THz spectrometer and the robot

• building a measurement configuration and plan to probe samples of teeth

• performing measurements on teeth of varying health status

• use x-ray benchmark techniques to verify health status

• using advanced signal processing (such as machine learning models, analytical models and hybrid models) to characterise the measured teeth.

• any related subject which the student thinks to be relevant for this work

For further information: Dook van Mechelen (j.l.m.v.mechelen-at-tue.nl)