One application of great interest is the determination of DNA-strands based on the binding state. Nowadays the commom method is the expensive and time-consuming fluorescent labelling. Biochips would require deposition of the (small amount of) material on the chip only. The permittivity of the sample material then indicates the binding state. This process is not only simpler, it also allows the usage of the material after the diagnosis since it is not contaminated with a fluorescent label.

The sensor-system consists of two parts, the THz measuring unit which generates and measures the THz-radiation and the sensor the so-called biochip. In our approach measurement unit and chip are independent of each other. Hence, it is possible the use TDS (time domain spectroscopy) or CW (CW = continuous wave) measurement technology with different kinds of hardware.

A vision of a Bio-Chip: An array consisting of 3x4 ringlike resonators, measuring only 0.7mm x 0.9mm. The DNA-strands are depicted on a larger scale. Real samples are as short as a few nanometers and cover only a small part of a ring.

The chip is loaded with biomolecules and placed in the THz-beam. It changes the signal depending on the dielectric number εm of the sample. The sample changes the resonant frequency of an on-chip resonator. This frequency shift is related to the εm of the sample. Our research focuses on the basic requirements of the biochip: A sharp spectral feature for reliable detection of the frequency shift, high field concentration to detect minute amounts of material and cost-effective fabrication.