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Water is considered to be the most essential and vital resources to sustaining life. Ensuring its delivery to people with no intrusion of harmful impurities, safe, reliable, and in an affordable manner is one of huge challenge amid to the ongoing climate transformations. This demands to introduce a cost effective and notion of real-time monitoring system that can detect the microbiological contaminants in aqueous solutions in timely manner to protect the public and environment health. In this paper, the prospects of integrating non-invasive terahertz (THz) waves with machine learning (ML) enabled technique is studied. The research explores a method of using Fourier transform Infrared Spectroscopy (FTIR) system to observe the absorption spectra and characteristics of three solvents solution , including salt, sugar and glucose with various quantity in aqueous solutions in the frequency range of 1 THz to 20 THz. In this study, due to the different molecular configuration and vibration modes of substances, distinct absorption spectra peaks were achieved for different concentrations of solvent solutions at certain sensitive THz region. Moreover, using measurements observations data, meaningful features are extracted and incorporated four algorithms such as random forest (RF), support vector machine (SVM), decision tree (D-tree) and k-nearest neighbour (KNN). The results demonstrated that RF obtained a higher accuracy of 84.74% in identifying the substance in aqueous solutions. Moreover, it was also found that RF with 97.98%, outperformed other classifiers for estimation of salts concentration added in aqueous solutions. However, for sugar and glucose concentrations, SVM exhibited a higher accuracy of 93.11% and 96.88%, respectively, compared to other classifiers. Thus, proposed technique incorporating ML with THz waves, may be significant in providing an efficient, cost-effective and real-time monitoring for water quality detection system.

We demonstrate a proof of concept highly miniaturised fluorescence imager and its application to detecting cancer in resected human colon cancer tissues. Fluorescence imaging modalities have already been successfully implemented in traditional endoscopy. However, the procedure still causes discomfort and requires sedation. Wireless fluorescence capsule endoscopy has the potential to improve diagnostic accuracy with less inconvenience for patients. In this paper we present a 5 mm $\times6$ mm $\times5$ mm optical block that is small enough to integrate into a capsule endoscope. The block integrates ultrathin filters for optical isolation and was successfully integrated with a sensitive CMOS SPAD array to detect green fluorescence from Flavin Adenine Dinucleotide (FAD), which is an endogenous fluorophore responsible for autofluorescence in human tissues, and fluorescence from the cancer selective molecular probe ProteoGREEN™-gGlu used to label colorectal cancer cells. In vitro studies were validated using a commercial Modulus™ Microplate reader. The potential use of the device in capsule endoscopy was further validated by imaging healthy and malignant resected human tissues from the colon to detect changes in autofluorescence signal that are crucial for cancer diagnosis.

This paper proposes a viable technique for the precise quantification of various amounts of salts added to distilled water using terahertz (THz) frequency. For this purpose, Fourier transform Infrared Spectroscopy (FTIR) system was employed to observe the absorption spectra and characteristics of salts solutions with varying level of salts. In this study, distinct absorption spectra peaks were achieved for different concentrations of salt solutions at certain sensitive THz region. The height of absorption peaks showed a strong correlation with the amount of salt added to the solution reflecting meaningful information about the presence of salts molecules added in distilled water. Through the outcomes of our study, we propose a method through which different minerals and potentially harmful contaminants can be found in water.

We present the design and fabrication of terahertz (THz) metamaterial (MM) absorbers and their monolithic integration into a commercial CMOS technology along with its respective readout electronics to produce a low-cost, uncooled, and high resolution THz camera. We first describe the work done on single band and broadband MM absorbers on custom substrates, then progress with a description of the integration of such resonators into a six metal layer 180 nm CMOS process and its coupling with two types of microbolometer sensors: Vanadium oxide (VOx) and silicon (Si) pn diode. Additionally, we demonstrate the integration of the THz sensors with readout electronics to form a monolithic THz focal plane array (FPA). Reflection images of a metallic object hidden in a manila envelope are recorded using both the VOx and Si pn diode detectors, demonstrating the suitability of the technology for stand-off detection of concealed objects. Finally, we present the current work toward scaling this technology into a 64 × 64 FPA.

Terahertz (THz) imaging has been demonstrated in numerous applications from medical to non-destructive evaluation (NDE), but current systems require expensive components, provide slow frame-rates and low resolutions. THz holography offers a potentially low-cost, high-performance alternative. Here we demonstrate the first full video-rate THz digital holography system at 2.52 THz (118.8 µm) using low-cost optical components. 2D digital reconstructions of samples are performed at frame-rates of 50 Hz - an order of magnitude higher than previous systems, whilst imaging of samples concealed in common packaging types demonstrates suitability for NDE applications. A lateral resolution of 250 µm was determined using a 1951 USAF target.

Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz-30 THz) have developed rapidly over the last 30 years. For most of the 20th Century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to 'real world' applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2017, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 18 sections that cover most of the key areas of THz science and technology. We hope that The 2017 Roadmap on THz science and technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies. OA hybrid

Refractive index sensing is attracting extensive interest. Limited by the weak light–matter interaction and the broad bandwidth of resonance, the figure of merit (FoM) of terahertz (THz) sensors is much lower than their counterparts in visible and infrared regions. Here, these two issues are addressed by incorporating a microfluidic channel as a slot layer into a grating slot waveguide (GSW), where guided‐mode resonance results in a narrowband resonant peak and the sensitivity increases remarkably due to the greatly concentrated electromagnetic fields in the slot layer. Both reflective and transmissive sensors are developed with the calculated quality (Q) factors two orders of magnitude larger than metamaterial and plasmonic sensors, and the sensitivities one order of magnitude larger than grating waveguide sensors, contributing to a record high FoM of 692. The measured results match well with the simulations considering the fabrication errors, where the degeneration of narrowband transmission peaks in experiments is attributed to the error of the microfluidic channel height and the divergence of the incident beam. The proposed unity‐integrating configuration with simultaneous optimizations of the resonance mechanism, and the spatial overlap between the sensing field and the analytes shows the potential for high sensitivity bio and chemo sensing.

A terahertz detector composed of a metamaterial absorber and micro-bolometer sensor integrated in a standard CMOS process is presented. The prototype demonstrates an innovative, uncooled, low cost, compact terahertz detector that is readily scaleable to high resolution focal plane array formats. The detector imaging capability is demonstrated in a transmission mode experiment.