Terahertz Gas-Sensors: Gas-Phase Spectroscopy and Multivariate Analysis for Medical and Security Applications

Kurzfassung

We developed a terahertz (THz) gas-phase spectrometer based on transmitter(TX)- and subharmonic receiver(RX)-chips fabricated in SiGe BiCMOS. A tunable TX and TX-array for 245 GHz with output powers of Pout=0dBm and 7dBm and a 500 GHz TX-array with Pout=-7dBm acts as tunable narrow band radiation sources. The THz beam is detected by the heterodyne RX. The high-resolution 2f-spectra were obtained by TX-frequency modulation and lock-in amplification of the RXs’ intermediate frequency (IF). The fingerprint-like spectra support a substance detection with absolute specifity, which we confirmed in our foregoing study by using multivariate algorithms (MVA) like principal components analysis (PCA) and partial least squares regression (PLS). We tested volatile organic compounds (VOCs) known as biomarkers and/or are classified as harmful by the EPA. We found a 100% qualitative substance detection and 2% mass fraction accuracy for the components in mixtures we prepared.