using a Schottky barrier diode (SBD). The dependency of the reflect- ance in sub-THz band on glucose and albumin concentrations in aqueous solutions has been measured in this experiment. It is observed that the reflectance is directly proportional to the concentration of glucose in the blood sample. Hence, the diffe- rence in the blood sugar levels of a healthy and diabetic person can be identified using the reflectance THz-TDS measurement. 12.11.2 DETECTION OF TUMOR-CANCER INFECTED CELLS The most common cause of death is due to the growth of tumor-cancer cells in the body. Although conventional screening techniques are available, early diagnosis through accurate measurements with several parametric analyses was lagging until the emergence of THz technologies. The THz spectroscopy and imaging with a robotic arm in our body serves as a powerful tool for in-situ measurements. In order to obtain a reliable and high-resolution image of a layer of skin, organ, tissues, veins, and the like, inside our body, the safest electromagnetic spectrum is THz radiation because of its non-ionizing nature. It can produce microscopic and macro- scopic transmission and reflection imaging with a fair contrast between diseased and normal cells. The Figure 12.18 shows an experimental setup of a THz imaging system under reflection geometry. In this setup, LT-GaAs based PCA illuminated by a Ti: Sapphire Lock-in detection Probe beam Optical delay Glass window Water Sample Z-quartz Beam splitter window Ti: Sapphire laser Pump beam Sample holder Excitation raster scanned FIGURE 12.18 Experimental setup of THz imaging system under reflection geometry. 5G Wireless Communication System in Healthcare Informatics laser is used as a THz emitter and detector. The resulting THz radiation is focused through off-axis parabolic mirrors onto the sample and the reflected THz beam is collected at the detector in the presence of an optically chopped probe beam. The detection mechanism has already been described in section 12.3. The optical chopper has bee