Terahertz imaging of titanium dioxide-free film coating hydration and tablet core interactions

 

Ma, Mingrui, Marwa Nassar, Jason Teckoe, and J. Axel Zeitler. "Terahertz imaging of titanium dioxide-free film coating hydration and tablet core interactions." International Journal of Pharmaceutics (2026): 126596.

Abstract

Titanium dioxide (TiO2) is often used as a white base pigment in film coatings, but recent EU restrictions on its use in food have prompted pharmaceutical manufacturers to seek alternatives. Terahertz pulsed imaging (TPI) was used to examine the hydration of TiO2-free immediate release formulations, either without an opacifier or using calcium carbonate (CaCO3). The coatings, made from polyvinyl alcohol (PVA) or hydroxypropyl methylcellulose (HPMC), were approximately 100 µm thick. TPI results indicated that the type of film coating influenced hydration and scattering effects. However, there was no evidence that TiO2-free coatings compromised tablet disintegration. Although the HPMC coating with CaCO3 gelled upon hydration, the tablets fully hydrated within the required time. These findings offer insights into the mechanistic impacts of alternative coatings in the industry.

see https://www.sciencedirect.com/science/article/pii/S037851732600044X

The 2023 terahertz science and technology roadmap

 Leitenstorfer, Alfred, Andrey S. Moskalenko, Tobias Kampfrath, Junichiro Kono, Enrique Castro-Camus, Kun Peng, Naser Qureshi et al. "The 2023 terahertz science and technology roadmap." Journal of Physics D: Applied Physics 56, no. 22 (2023): 223001.

Abstract

Terahertz (THz) radiation encompasses a wide spectral range within the electromagnetic spectrum that extends from microwaves to the far infrared (100 GHz–∼30 THz). Within its frequency boundaries exist a broad variety of scientific disciplines that have presented, and continue to present, technical challenges to researchers. During the past 50 years, for instance, the demands of the scientific community have substantially evolved and with a need for advanced instrumentation to support radio astronomy, Earth observation, weather forecasting, security imaging, telecommunications, non-destructive device testing and much more. Furthermore, applications have required an emergence of technology from the laboratory environment to production-scale supply and in-the-field deployments ranging from harsh ground-based locations to deep space. In addressing these requirements, the research and development community has advanced related technology and bridged the transition between electronics and photonics that high frequency operation demands. The multidisciplinary nature of THz work was our stimulus for creating the 2017 THz Science and Technology Roadmap (Dhillon et al 2017 J. Phys. D: Appl. Phys. 50 043001). As one might envisage, though, there remains much to explore both scientifically and technically and the field has continued to develop and expand rapidly. It is timely, therefore, to revise our previous roadmap and in this 2023 version we both provide an update on key developments in established technical areas that have important scientific and public benefit, and highlight new and emerging areas that show particular promise. The developments that we describe thus span from fundamental scientific research, such as THz astronomy and the emergent area of THz quantum optics, to highly applied and commercially and societally impactful subjects that include 6G THz communications, medical imaging, and climate monitoring and prediction. Our Roadmap vision draws upon the expertise and perspective of multiple international specialists that together provide an overview of past developments and the likely challenges facing the field of THz science and technology in future decades. The document is written in a form that is accessible to policy makers who wish to gain an overview of the current state of the THz art, and for the non-specialist and curious who wish to understand available technology and challenges. A such, our experts deliver a ‘snapshot’ introduction to the current status of the field and provide suggestions for exciting future technical development directions. Ultimately, we intend the Roadmap to portray the advantages and benefits of the THz domain and to stimulate further exploration of the field in support of scientific research and commercial realisation.

see https://iopscience.iop.org/article/10.1088/1361-6463/acbe4c/meta

Application of Terahertz Time-Domain Spectroscopy to Study the Microheterogeneities of Solutions: A Case Study of Aqueous Sugar Solutions

Penkov, Nikita V. "Application of terahertz time-domain spectroscopy to study the microheterogeneities of solutions: a case study of aqueous sugar solutions." In Photonics, vol. 10, no. 8, p. 887. MDPI, 2023.#

Abstract

The phenomenon of the formation of microheterogeneities (MHs) in solutions, which, according to chemical handbooks, are considered true solutions, has been known for a long time. MHs have been found in more than 100 binary solutions, many of which are used both in various scientific studies and in life. However, the nature of this phenomenon is largely unclear. It is only well-known that MHs are stable areas of increased concentration of one of the components of the solution. The main reason for the poor knowledge of MHs is the use of very few experimental methods, mainly light scattering methods. In this paper, the terahertz time-domain spectroscopy method was used for the first time to study MHs using the example of aqueous solutions of three sugars: glucose, fructose, and sucrose. This method gives the spectra of complex permittivity in the terahertz range, which are very informative when studying the hydrate shells of molecules in solutions. The idea of this study was that structuring sugar molecules with the formation of MHs changes their hydration. The characteristics of sugar hydration in solutions before and after filtration through a 20 nm filter, leading to the destruction of MHs, were compared. It has been shown that the water binding in the MHs of all three solutions is increased compared with the hydrate shells of individual sugar molecules. Also, for MHs’ fructose solution, a decrease in the number of hydrogen bonds between water molecules and an increase in the number of free water molecules was shown, which is not observed in MH glucose and sucrose solutions. This is explained by mutarotations of fructose molecules, leading to permanent significant rearrangements of the water structure in MHs. Thus, terahertz time-domain spectroscopy provides fundamentally new information about the MHs of aqueous solutions at the level of their hydration characteristics. The presence of MHs in solutions is a significant factor that has never been taken into account when studying the hydrate shells of various molecules in solutions using THz spectroscopy.

see https://www.mdpi.com/2304-6732/10/8/887

Application of Terahertz Pulses to Non-Destructive Testing

 Zarrinkhat, Faezeh, Philip F. Taday and Donald D. Arnone. "Application of terahertz pulses to non-destructive testing." Journal of Non Destructive Testing and Evaluation (JNDE) 20, no. 2 (2023): 35-43.

Abstract
For the past twenty years, TeraView has been a world leader in the application of terahertz pulses to solve problems for industry .Terahertz technology provides the opportunity of remote, safe, fast and accurate sensing. In recent years, there has been a growing interest from industry in applying terahertz pulses to process control .In this paper, there is a brief review of the generation and detection of terahertz waves (0.1 THz to 6THz) using photoconductive antennas. The applications of time-domain spectroscopy to gas, liquid and solids are discussed. Then, a number of industrial applications of terahertz pulsed imaging such as solar cells, pharmaceutical, battery production and automotive industries are highlighted.

see https://jnde.isnt.in/index.php/JNDE/article/view/51

Terahertz time-domain spectro-imaging and hyperspectral imagery to investigate a historical Longwy glazed ceramic

 Fauquet, Frédéric, Francesca Galluzzi, Philip F. Taday, Rémy Chapoulie, Aurélie Mounier, A. Ben Amara, and Patrick Mounaix. "Terahertz time-domain spectro-imaging and hyperspectral imagery to investigate a historical Longwy glazed ceramic." Scientific Reports 14, no. 1 (2024): 19248.

Abstract

In this paper, we present the potential of Terahertz Time-Domain Imaging (THz-TDI) as a tool to perform non-invasive 3D analysis of an ancient enamel plate manufactured by Longwy Company in France. The THz data collected in the reflection mode were processed using noise filtering procedures and an advanced imaging approach. The results validate the capability to identify glaze layers and the thickness of ceramic materials. To characterize the nature of the pigments, we also use with X-ray images, visible near-infrared hyperspectral imaging spectroscopy, and p-XRF (portable X-ray fluorescence) to qualitatively and quantitively identify the materials used. The obtained information enables a better understanding of the decoration chromogens nature and, thus, to determine the color palette of the artists who produced such decorative object. We also establish the efficiency of a focus, Z-tracker, which enables to perform THz imaging on non-flat samples and to attenuate artifacts obtained with a short focus lens. Then, 3D images are extracted and generated, providing a real vision. We also report the evaluation of the internal damage state through the detection of fractures.

see https://www.nature.com/articles/s41598-024-69697-6

Terahertz Assessment of the Battery Electrodes Save Production Costs of Electric Vehicles

Khat, F. Zarrin, A. Pentland, P. F. Taday, and D. D. Arnone. "Terahertz Assessment of the Battery Electrodes Save Production Costs of Electric Vehicles." Journal of Non Destructive Testing and Evaluation (JNDE) 21, no. 2 (2024): 33-40. 

Abstract

The electric vehicle market has experienced remarkable growth in recent years. A primary objective within this industry is to lower production costs. Notably, battery packs, which constitute up to 40% of the total production cost, allocate about 64% of this to the manufacturing of electrodes. It is vital to monitor key battery parameters such as thickness, loading, density, conductivity, and porosity to minimize waste during electrode production. Until recently, there was no technology capable of simultaneously tracking these parameters. However, terahertz technology has emerged as a powerful, non-destructive, and safe method for assessing battery electrodes.

Battery electrodes are coated on substrates made of materials like aluminium and copper. Since metals completely reflect terahertz waves, it's possible to measure the electrodes in reflection mode. This approach allows for the determination of the coating's thickness and its complex refractive index, which can be interpreted to deduce key electrode parameters.

In our study, we utilized TeraView's latest advancement, the TeraCota, a terahertz system designed for industrial applications, equipped with a self-referencing terahertz sensor. The sensor, mounted on a gantry, provided a terahertz image of the electrode loading and allowed for a direct comparison with an optical image, revealing defects on the cathode. We achieved an accuracy of 0.01 g/cm3 when comparing density measurements obtained through a terahertz sensor with those measured physically in the lab. Furthermore, the thickness measurements via the terahertz system agreed with those obtained using a micrometre to within less than 1 µm. Similarly, when comparing the conductivity measured by terahertz with DC conductivity measured via a four-point probe, the trends were consistent. Ongoing research into porosity has shown that the refractive index correlates with the porosity of specific electrode sets, indicating the potential for broader application. This comprehensive approach demonstrates the significant advantages of integrating terahertz technology into the battery electrode manufacturing process, potentially revolutionizing the industry by enhancing efficiency and reducing waste.

see https://jnde.isnt.in/index.php/JNDE/article/view/84

Exploring Porosity in Battery Electrodes: Terahertz Technology Unveiling Remote Sensing

 Zarrinkhat, Faezeh, Arturo I. Hernandez-Serrano, Alasdair Pentland, Philip F. Taday, Donald D. Arnone, and Michael Pepper. "Exploring porosity in battery electrodes: terahertz technology unveiling remote sensing." In 2024 49th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), pp. 1-2. IEEE, 2024.

Abstract:

Porosity significantly influences lithium-ion battery performance, impacting cell capacity, voltage, and specific power - critical to designers. Terahertz technology enables non-destructive, remote porosity assessment, addressing limitations in current measurement methods.

see https://ieeexplore.ieee.org/abstract/document/10697663

Optical and terahertz methods for studying easel oil paintings

 Bolshakov, Ivan S., Anastasiya A. Lykina, Olga V. Kravtsenyuk, Sergey V. Sirro, Vyacheslav Y. Toropov, Andrey R. Tsvetkov, Philip F. Taday, Donald D. Arnone, and Olga A. Smolyanskaya. "Optical and terahertz methods for studying easel oil paintings." Journal of Optical Technology 91, no. 5 (2024): 323-329.

Abstract

Subject of study. This study focuses on the application of terahertz tomography methods to easel oil paintings. Aim of study. The aim of this study is to assess the effectiveness of terahertz tomography in analyzing the layered structure of artworks and detecting hidden damage, elements, and annotations. Method. The study employed traditional analysis methods, such as infrared, ultraviolet fluorescence, and X-ray imaging. Special emphasis was placed on terahertz tomography, which enables non-invasive imaging of internal structures. Main results. The study showed that terahertz tomography allows for the differentiation of materials used in oil paintings. This method enables a detailed examination of the layered structure without damaging the object under investigation, revealing elements that cannot be detected using other methods. The novelty of this study lies in the proposed application of terahertz tomography for preliminary in situ examination of paintings to detect hidden defects and possible inscriptions on the reverse side of artworks. Practical significance. The results obtained from this study are valuable for researching, assessing the preservation status of, and restoring oil paintings. Specifically, the proposed method is suitable for detecting defects and hidden elements beneath paint layers without damaging the colorful surface. The terahertz tomography method proves particularly effective when applied in situ, as it does not require paintings to be dismantled.

see https://opg.optica.org/jot/abstract.cfm?uri=jot-91-5-323

The Measurement of the Coating Uniformity of Lithium Iron Phosphate Cathodes on Metal Substrates with Terahertz Time-domain Spectroscopy

 Zarrinkhat, Faezeh, Alasdair Pentland, Carl Reynolds, Emma Kendrick, and Philip F. Taday. "The Measurement of the Coating Uniformity of Lithium Iron Phosphate Cathodes on Metal Substrates with Terahertz Time-domain Spectroscopy." In 2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), pp. 1-2. IEEE, 2023.

Abstract:

For the first time, the thickness uniformity of lithium iron phosphate (LFP) cathodes are measured using terahertz time-domain spectroscopy. Cathodes are widely manufactured with cobalt, however providing cobalt material comes with supply and health issues. LFP cathodes are introduced as an alternative to tackle this challenge. The aim is to use terahertz pulses to generate an on-line tool to undertake manufacturing process control. Different thickness of cathodes compressed to different densities is measured and the uniformity of their coating is inspected.

see https://ieeexplore.ieee.org/abstract/document/10299358

Self-referencing Reflection Sensor for Industrial Applications

Zarrinkhat, Faezeh, Bryan Cole, Alasdair Pentland, and Philip F. Taday. "Self-referencing reflection sensor for industrial applications." In 2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), pp. 1-2. IEEE, 2023. 

Abstract:

Terahertz sensors have found their way into many industrial applications, though undertaking regular reference measurements could be inconvenient on some occasions. A sensor with a self-referencing (SR) mechanism (in a linear configuration) is designed and manufactured to tackle the challenge. The sensor head is used on Lithium Iron Phosphate (LFP) cathodes to report the thickness and refractive index of the material.

see https://ieeexplore.ieee.org/abstract/document/10299020

Incorporating Time-Domain Reflectometry in Chip-Level Failure Analysis Workflow: Case Studies

 Liao, Joy Y., Khanh Giang, Timothy Pham, and Howard Lee Marks. "Incorporating time-domain reflectometry in chip-level failure analysis workflow: case studies." In International Symposium for Testing and Failure Analysis, vol. 84741, pp. 145-150. ASM International, 2023.

Abstract

Non-destructive electrical fault isolation (FI) techniques such as emission- and laser-based techniques have been utilized widely for chip-level failure analysis (FA). However, these techniques by themselves can sometimes be inadequate for certain failure modes. In this paper, we present six FA case studies using Time-domain Reflectometry (Electro-optical terahertz pulse reflectometry, EOTPR) in combination with the traditional FI techniques. We also present continuing development in making EOTPR accessible to the semiconductor process and packaging communities.

see https://dl.asminternational.org/istfa/proceedings-abstract/ISTFA2023/84741/145/28577

Recent Developments in EOTPR Towards a Fully Automated Tool for High Volume Failure Analysis

White, Tom, Jesse Alton, Brett Gibson, Martin Igarashi, Joy Liao, Timothy Pham, and Howard Marks. "Recent Developments in EOTPR Towards a Fully Automated Tool for High Volume Failure Analysis." In 2025 IEEE International Reliability Physics Symposium (IRPS), pp. 1-5. IEEE, 2025.

Abstract

Developments in backside power delivery (BPD) technology will become increasingly important for advanced semiconductors, but will present new challenges for failure analysis (FA) labs. Electro-Optical TeraHertz Pulsed Reflectometry (EOTPR) is a well-established electrical FA technique for package level open and leakage faults, but has comparatively little use for detecting die-level faults. Here, two case studies are presented that demonstrate how EOTPR can be used to localize faults within a die, highlighting how EOTPR could be utilized for BPD devices. Recent and future key developments in EOTPR are also presented.

see https://ieeexplore.ieee.org/abstract/document/10983830

Reduction in Reflection Signal Losses in Complex Terahertz Optical Elements Through Tailored Oil Application

 Kaluza, Mateusz, Adrianna Nieradka, Mateusz Surma, Wojciech Krauze, and Agnieszka Siemion. "Reduction in Reflection Signal Losses in Complex Terahertz Optical Elements Through Tailored Oil Application." Applied Sciences 15, no. 20 (2025): 11167.

Abstract

In complex terahertz (THz) systems, multiple optical elements are often combined to achieve advanced functionalities. However, unwanted Fresnel reflections at their interfaces and between components lead to parasitic interference effects and signal losses. This study presents oil-based refractive-index-matching fillers integrated with additively manufactured assemblies to suppress Fresnel reflections and enhance overall optical system performance. The optical properties of 20 plant-based, synthetic, and mineral oils were investigated using terahertz time-domain spectroscopy (THz TDS). Furthermore, a multilayer structure was designed and experimentally verified, fabricated via fused deposition modeling (FDM) using highly transparent cyclic olefin copolymer (COC). The results demonstrate that the use of tailored oils reduces Fresnel reflection signal losses and also mitigates parasitic interference within the system, thereby improving the effective efficiency of the optical system. Additionally, THz TDS measurements on multilayer structures revealed that, in imaging configurations, the application of refractive-index-matched oils increases the signal gain by 2.33 times. These findings highlight the potential of oil-based index-matching fillers for imaging multilayered objects and mitigating delamination effects in optical elements.

see https://www.mdpi.com/2076-3417/15/20/11167

The first annual Showcase of the EPSRC NetworkPlus in Terahertz System

 📣 We are pleased to announce that the first annual Showcase of the EPSRC NetworkPlus in Terahertz Systems will take place in Leeds on 21st and 22nd April 2026 📣

The Showcase will bring together academics and representatives working in industry and non-academic research organisations for two days of engaging discussions on future prioritisation areas for THz science and technology across the UK and Europe. We will also provide information on our Flexible Fund, which will support researchers in exploring some of these opportunities through seedcorn projects. There will be plenty of opportunities for networking – including a poster session and conference dinner – and for helping to shape the future of the NetworkPlus.

For further details and to register your interest in attending the meeting, please see below 👇 The deadline for EOIs is Friday 30th January.

Using density changes to monitor blending with magnesium stearate by terahertz time-domain spectroscopy

Anuschek, Moritz, Thea Nilsson, Anne Linnet Skelbæk-Lorenzen, Thomas Kvistgaard Vilhelmsen, J. Axel Zeitler, and Jukka Rantanen. "Using density changes to monitor blending with magnesium stearate by terahertz time-domain spectroscopy." International Journal of Pharmaceutics 672 (2025): 125303.

Abstract

Magnesium stearate (MgSt) is among the most common excipients and the most common lubricant in solid oral products. It is primarily added to tablet formulations to ease ejection during tablet compression. While commonly present in low concentrations, the addition of MgSt substantially affects the final tablet properties. Its impact is further not only concentration dependent but also varies with exposure of the formulation to shear, which worst-case results in over-lubrication. The presented study investigated the applicability of terahertz time-domain spectroscopy (THz-TDS) to monitor the shear-induced blend densification of microcrystalline cellulose blended with MgSt over a range of concentrations (0.3, 0.7, and 1.0 %). The effect of shear was investigated by variation of blending times (5 – 20 min) in a diffusion blender. THz-TDS measurements of the powder blends were acquired in transmission by measuring directly through the mixing container. The refractive index at terahertz frequencies was found to be sufficiently sensitive to resolve the densification of the blend with increased blending times. Thus, THz-TDS blend density measurements can be used as a surrogate parameter to evaluate the total shear exposure of a blend. Considerations regarding implementation are discussed. In the context the approach was integrated with the well-described THz-TDS-based tablet porosity analysis into a unified model to monitor and predict the tensile strength. Including the THz-TDS measurement on the blend allowed for a more accurate description of the tensile strength, reducing the root mean squared error by over 40 % (0.33 MPa). The possibility of monitoring the density changes of a blend non-invasively makes THz-TDS a promising process analytical technology approach for controlling the total shear impact on lubricated blends and tablet quality.

see https://www.sciencedirect.com/science/article/pii/S0378517325001395

Terahertz non-destructive testing of thin self-lubricating bearing coating thickness based on SOMP sparse representation

 Huang, Yi, Hailiang Wang, Weiqiang Chen, Shuncong Zhong, Tingting Shi, Caihong Zhuang, Fuwei Sun, Yonglin Huang, and Zhenghao Zhang. "Terahertz non-destructive testing of thin self-lubricating bearing coating thickness based on SOMP sparse representation." Infrared Physics & Technology (2025): 106223.

Abstract

The thickness of aviation solid thin self-lubricating bearing coatings gradually decreases during wear, which leads to severe echo overlapping in terahertz non-destructive testing. This adversely affects the extraction of coating thickness information. In this paper, a thin coating thickness measurement method that integrates secondary orthogonal matching pursuit (SOMP) sparse representation with the time-of-flight (TOF) is proposed. The propagation characteristics of terahertz waves are firstly investigated, and the convolutional dictionary matrix is constructed based on the reference signal. Subsequently, a series of suboptimal atoms are selected by maximizing the inner product between the reflected signal and the column vector. On this basis, the optimal atoms are further identified using the minimum envelope entropy index to reconstruct the impulse response. The coating thickness is finally quantitatively calculated using the TOF method. The experiments demonstrate that this method can detect coatings thinner than 15 μm with a relative error below 5 %. This study is expected to provide an effective method for accurately measuring the thickness of thin self-lubricating bearing coatings.

see https://www.sciencedirect.com/science/article/abs/pii/S135044952500516X

Polarimetry terahertz imaging of human breast cancer surgical specimens

Gurjar, Nikita, Keith Bailey, and Magda El-Shenawee. "Polarimetry terahertz imaging of human breast cancer surgical specimens." Journal of Medical Imaging 11, no. 6 (2024): 065503-065503.

Abstract

Purpose
We investigate terahertz (THz) polarimetry imaging of seven human breast cancer surgical specimens. The goal is to enhance image contrast between adjacent tissue types of cancer, healthy collagen, and fat in excised breast tumors. Based on the biological perception of random growth of cancer and invasion of surrounding healthy tissues in the breast, we hypothesize that cancerous cells interact with the THz electric field in a different manner compared with healthy cells. This difference can be best captured using multiple polarizations instead of single polarization.
Approach
Time domain pulsed signals are experimentally collected from each pixel of the specimen in horizontal–horizontal, vertical–horizontal, vertical–vertical, and horizontal–vertical polarizations. The time domain pulses are transformed to the frequency domain to obtain the power spectra and 16 Mueller matrix images. The whole-slide pathology imaging was used to interpret and label all images.
Results
The results of the cross and co-polarization power spectrum images demonstrated a strong dependency on the tissue orientation with respect to the emitted and detected electric fields. At the 130-deg rotation angle of the scanned samples, the detector showed the strongest reflected signal in cross-polarization. Furthermore, the Mueller matrix images consistently demonstrated patterns in fresh and block tissues confirming the differentiation between tissue types in breast tumor specimens.
Conclusions
THz polarimetry imaging shows a potential for improving image contrast in excised tumor tissues compared with single polarization imaging. Cross-polarization signals demonstrated smaller amplitudes compared with co-polarized signals. However, averaging the signal during measurements has tremendously improved the image. Furthermore, in post-processing, averaging the frequency domain images and the Mueller matrix elements with respect to frequency has led to better image contrast. Some patterns in the Mueller matrix images were difficult to interpret leading to the necessity of more investigation of the Mueller matrix and its physiological interpretation of breast tumor tissues.

see https://www.spiedigitallibrary.org/journals/journal-of-medical-imaging/volume-11/issue-6/065503/Polarimetry-terahertz-imaging-of-human-breast-cancer-surgical-specimens/10.1117/1.JMI.11.6.065503.full

NetworkPlus in THz Systems Special Interest Group in Healthcare - Introductory Meeting

Hyper-Integrated CAD Database for One-Shot EOTPR Fault Localization in Heterogeneous Sip-on-Board Assemblies

 Bhattacherjee, Arpan, and Joy Liao. "Hyper-Integrated CAD Database for One-Shot EOTPR Fault Localization in Heterogeneous Sip-on-Board Assemblies." In International Symposium for Testing and Failure Analysis, vol. 85212, pp. 64-67. ASM International, 2025.

Abstract

The increasing complexity of datacenter accelerators and artificial intelligence (AI) inference systems has driven rapid adoption of sophisticated heterogeneous system-in-package (SiP) architectures. These advanced packages integrate multilayer printed circuit boards (PCBs), organic substrates, silicon interposers, and high-density integrated circuits, delivering significant performance improvements. However, these densely integrated architectures introduce substantial challenges for accurate and timely failure analysis (FA). Electro-Optical Terahertz Pulse Reflectometry (EOTPR), a non-destructive diagnostic method, offers superior fault localization compared to traditional techniques. Nonetheless, its practical implementation in complex SiP systems has been limited by fragmented CAD data and iterative manual analyses, significantly extending diagnostic timelines. This paper presents a novel “hyper-integrated” CAD database methodology, where disparate design datasets are automatically consolidated into a unified navigation database. This approach creates a static digital twin of the failing board-level device, enabling precise, “one-shot” fault localization using EOTPR. Experimental validation on advanced datacenter accelerator hardware demonstrates substantial improvements in diagnostic speed, accuracy, and efficiency, emphasizing the practical benefits of the hyper-integrated approach for state-of-the-art semiconductor failure analysis.

see https://dl.asminternational.org/istfa/proceedings/ISTFA2025/85212/64/35164

EOTPR Fine Pitch Probing for Die-to-Die Interconnect Failure Analysis

 Zee, Bernice, Wen Qiu, Aaron Wai Ken Lee, Jesse Alton, Thomas White, David Kim, and Martin Igarashi. "EOTPR Fine Pitch Probing for Die-to-Die Interconnect Failure Analysis." In International Symposium for Testing and Failure Analysis, vol. 85212, pp. 400-403. ASM International, 2025.

Abstract

Debug and physical failure analysis (PFA) of heterogeneously integrated semiconductor packages, particularly die-to-die (D2D) input/output (I/O) type fails, has become very challenging due to the lack of direct access to the I/Os from the package substrate to do static open/shorts fault isolation and limited test program granularity to determine which location along the D2D interconnect trace is failing. Thus, a suitable electrical fault isolation technique is required to ensure high success rate for root cause analysis. This paper discusses how EOTPR is used to isolate defects on a D2D interconnect trace of a chiplet advanced packaging using local silicon bridge with reasonable accuracy. Minimal sample preparation was needed to expose the I/O bumps for probing, thus minimizing the risk of artifacts that may cause the defect to be lost. A case study will demonstrate the successful application of the technique.

see https://dl.asminternational.org/istfa/proceedings/ISTFA2025/85212/400/35215

From powder to spectrum: A tutorial of terahertz transmission time-domain spectroscopy

 Zarrella, Salvatore, Elena Wanvig i Dot, J. Axel Zeitler, and Timothy M. Korter. "From powder to spectrum: A tutorial of terahertz transmission time-domain spectroscopy." International Journal of Pharmaceutics (2026): 126586.

Abstract

Terahertz time-domain spectroscopy (THz-TDS) is a non-destructive, high-resolution method that probes low-frequency vibrational modes and intermolecular interactions between the microwave and infrared regions inaccessible by other spectroscopic methods. The technique is established in the pharmaceutical sciences and is now spreading to other areas in need of an extensive understanding of material properties. Despite the growth in THz applications, measurements are still confined to specialized laboratories. This tutorial seeks to provide a practical standard operating procedure for taking transmission measurements of compacted powders and is designed for new users across disciplines. We describe sample preparation, spectrometer configuration, data acquisition, signal processing, quantitative analysis, and troubleshooting. Emphasis is placed on practical strategies such as selecting appropriate diluents, ensuring homogeneous sample mixing, optimizing pellet thickness, aligning the optical setup, and handling spectral artifacts like Fabry–Pérot etalons. Additionally, the tutorial guides users through data transformation using FFT and apodization techniques to extract accurate optical constants such as refractive index and absorption coefficients. By consolidating best practices and minimizing technical barriers, this resource aims to make THz spectroscopy more accessible and reproducible for researchers across disciplines.

see https://www.sciencedirect.com/science/article/pii/S0378517326000347

Ancient enamel plate characterized by Time domain spectro imaging

Mounaix, Patrick, Philip F. Taday, Frédéric Fauquet, Rémy Chapoulie, Aurélie Mounier, and A. Ben Amara. "Ancient enamel plate characterized by Time domain spectro imaging." In 2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), pp. 1-2. IEEE, 2023.

Abstract:

We report on further development of terahertz systems for measuring the thicknesses and the detection of fracture in art science. Analysis of time-domain data is described and the results of measurements made on ancient enamel plate are presented. We also show X-Ray images and hyperspectral visible and infrared images to identify the pigments used. We also test the Z tracker developed by Teraview Ltd and demonstrate the possibility to perform THz imaging on non-flat samples.

see https://ieeexplore.ieee.org/abstract/document/10299322

Dual-frequency liquid crystals as tunable materials for beam steering in terahertz photonics

Dual-frequency liquid crystals as tunable materials for beam steering in terahertz photonics

PHOTONICS LETTERS OF POLAND, VOL. 17 (4), 85-87 (2025) 

Oleksandra Gridyakina1 , Urszula Chodorow , Adrianna Nieradka , Agnieszka Siemion , Janusz Parka , Piotr Lesiak and Tomasz R. Woliński 

Abstract

Dual-frequency liquid crystal (LC) materials for tunable beam steering in the 0.1–3.5 THz range were investigated. Recent LC formulations exhibit a low loss tangent, high polarization coefficients, and significant dielectric and optical anisotropies, including suitably high birefringence for effective THz modulation. We have implemented this material in electrically tunable phase shifters and beam-steering elements, demonstrating their ability to operate with low absorption and controllable birefringence. The obtained characteristics suggest that dual frequency LCs could be used to create compact, efficient, and highly tunable THz photonic and sensing components. This study outlines the performance parameters relevant to practical THz devices and highlights their potential for reconfigurable photonic architectures.

… The measurements of DFLC optical properties were performed using a THz time domain spectroscopy (THzTDS) - the TeraView TeraPulse Lx Modular System at room temperature. To eliminate the adverse effects of atmospheric water vapor, the …