Philip F Taday

• TeraView Limited

Spectroscopic diagnostics have great potential in clinical applications, enabling the assessment of biological tissues and fluids through their spectral signatures. The accuracy and reliability of these techniques are paramount for their integration into routine clinical workflows. Several challenges—such as instrumental drift, environmental fluctu...

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 an...

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...

Diabetes screening is traditionally complex, inefficient, and reliant on invasive sampling. This study evaluates near-infrared spectroscopy for non-invasive detection of glycated keratin in nails in vivo. Glycation of keratin, prevalent in tissues like nails and skin, is a key indicator of T2DM risk. In this study involving 200 participants (100 wi...

Terahertz technology represents a cutting-edge advancement in non-destructive testing, facilitating rapid and inline inspection of high-value coatings across various industries including automotive, pharmaceuticals, semiconductors, and aerospace. Among its recent applications is the assessment of battery electrodes. In this study, five mixed niobiu...

This article contains a brief summary of areas where terahertz technology is making an impact in research and industrial applications. We cover some of its uses in the pharmaceutical setting, where both imaging and spectroscopy play important roles. Medical applications are also being pursued in many research laboratories, primarily for imaging pur...

The goal of this study was to detect and inspect the paint layers below the surface independently of any surface features. Using the for THz-TDS imaging system, we obtained contrast images of layers of paint applied to the back side of the canvas. The most difficult task that the researchers have set themselves has not yet been fully resolved. When...

This study aims to objectively inform curators when terahertz time-domain (TD) imaging set in reflection mode is likely to give well-contrasted images of inscriptions in a complex archival document and is a useful non-invasive alternative to current digitisation processes. To this end, the dispersive refractive indices and absorption coefficients f...

We investigate the potential of terahertz time-domain imaging in reflection mode to reveal archival information in documents in a non-invasive way. In particular, this study explores the parameters and signal processing tools that can be used to produce well-contrasted terahertz images of topographic features commonly found in archival documents, s...

Particle size is shown to influence both the overall value and the measurement precision of the refractive index and absorption coefficient of a sample diluted with high density polyethylene (HDPE) powder and compressed in a pellet. However, excessive grinding of a sample before it is mixed with HDPE powder can result in the formation of large part...

We demonstrate improved terahertz (THz) modulation using thermally crystallized germanium telluride (GeTe) thin films. GeTe is a chalcogenide material that exhibits a nonvolatile, amorphous to crystalline phase change at approximately 200 °C, as well as six orders of magnitude decreased electrical resistivity. In this study, amorphous GeTe thin fil...

Iron sulfate compounds have been used extensively to produce iron gall ink, a widely used writing ink in the western world from the 12th-20th centuries. Iron gall ink is well known to corrode writing supports, so detection of iron species is important for the preservation of historical artwork and documents. Iron(II) sulfate readily changes hydrati...

In this study we discuss the influence of the state of degradation, the three-dimensional fibrous structure and the presence of calcium compounds on terahertz absorption properties of historic parchment in the interval 45-85 cm-1, based on the analysis of 32 archival parchment samples, with terahertz time-domain spectroscopy in transmission mode, o...

Terahertz (THz) vibrational spectroscopy is a promising tool for the non-destructive and potentially non-invasive characterization of historical objects, which can provide information on the materials used for their production as well as identify and monitor their chemical degradation. Copper sulfate (CuSO4) has drawn interest due to its inclusion...

We propose to use terahertz pulsed imaging (TPI) as a novel tool to characterise the thickness and uniformity of up to four layers of car paint on both metallic and non-metallic substrates. Results of the terahertz measurements are compared with other techniques, i.e. ultrasound, eddy current measurements, and X-ray computed tomography and good con...

Terahertz ATR spectroscopy was used to monitor the crystallization of sugar on confectionary products. The time-dependent spectroscopy could used to follow phase transition from the aqueous phase into a glassy state followed by a crystallization of the sugar on the ATR window. Terahertz pulsed imaging was also used to investigated the final product...

The potential of terahertz-time domain spectroscopy (THz-TDS) as a diagnostic tool for studies of inks in historical documents is investigated in this paper. Transmission mode THz-TDS was performed on historically informed model writing and drawing inks. Carbon black, bistre and sepia inks show featureless spectra between 5 and 75 cm(-1) (0.15-2.25...

In this study, terahertz pulsed imaging (TPI) was employed to investigate the effect of the coating equipment (fluid bed and drum coater) on the structure of the applied film coating and subsequent dissolution behaviour. Six tablets from every batch coated with the same delayed release coating formulation under recommended process conditions (provi...

Electro-optical terahertz pulse reflectometry (EOTPR) was introduced last year to isolate faults in advanced IC packages. The EOTPR system provides 10μm accuracy that can be used to non-destructively localize a package-level failure. In this paper, an EOTPR system is used for non-destructive fault isolation and identification for both 2D and 2.5D w...

Terahertz pulsed spectroscopy was used to qualitatively detect ciprofloxacin hydrochloride monohydrate (CPFX·HCl·H(2)O) in tablets, and terahertz pulsed imaging (TPI) was used to scrutinize not only the coating state but also the density distribution of tablets produced by several manufacturers. TPI was also used to evaluate distinguishability amon...

Terahertz (THz) time-domain spectroscopy and 3D THz pulsed imaging have been explored with regard to polymer materials, both commodity and historic polymers. A systematic spectroscopic study of a wide range of different polymer materials showed significant differences in their spectra. Polyolefins and polystyrenes generally exhibit lower absorption...

Quality attribute of tablet coating on a film-coating process was investigated by a terahertz pulsed imaging. The time-dependent change of intensities of reflex THz pulse and coating layer thicknesses were compared. The forming of coating layer was observed at 30 min after the process was started.

Optical coherence tomography (OCT) and terahertz pulsed imaging (TPI) are two powerful techniques allowing high quality cross-sectional images from within scattering media to be obtained non-destructively. In this paper, we report experimental results of using OCT and TPI for quantitatively characterizing pharmaceutical tablet coatings in the thick...

Recent advances in semiconductors and the availability of robust industrial femtosecond pulsed lasers have resulted in a rapid exploration of terahertz region by the pharmaceutical industry. Terahertz radiation generated at a source can penetrate up to several millimeters into a sample, and whenever there is change in refractive index due to either...

Part of the fluorescence excitation spectrum and several single vibronic level dispersed fluorescence spectra of the cis and trans rotamers of 3-methylstyrene in a supersonic jet have been obtained. Both rotamers show overlapping progressions involving methyl and vinyl torsional vibrations in S0 and involving just the methyl torsion in S1. The resu...

Coatings are applied to pharmaceutical tablets (or pills) to for either cosmetic or release control reasons. Cosmetic coatings control the colour or to mask the taste of an active ingredient; the thickness of these coating is not critical to the performance of the product. On the other hand the thickness and uniformity of a controlled release coati...

Combination of spectroscopic methods: THz, FIR and Raman spectroscopy (see figure) allow the assignment of all intra and inter molecular vibrational modes in imidazolium-based ionic liquids in the low frequency range between 2 and 300 cm−1. Although THz spectroscopy is very sensitive for this frequency range, clearly no significant contribution cou...

We present Terahertz (THz) imaging with a 1D multichannel time-domain spectroscopy (TDS) system which operates with a photoconductive array of 15 detection channels excited by a 1030 nm femtosecond fiber laser. The emitter and detector are photoconductive antennas based on InGaAs/InAlAs multi-layer heterostructures (MLHS). We characterized the THz...

Understanding the coating unit operation is imperative to improve product quality and reduce output risks for coated solid dosage forms. Three batches of sustained-release tablets coated with the same process parameters (pan speed, spray rate, etc.) were subjected to terahertz pulsed imaging (TPI) analysis followed by dissolution testing. Mean diss...

Terahertz pulsed imaging (TPI) and optical coherence tomography (OCT) are two powerful techniques allowing high quality three-dimensional images from within scattering media to be obtained noninvasively. In this paper, we report experimental results of using TPI and OCT for characterizing layered samples including pharmaceutical coatings. We found...

Film coating thickness and terahertz electric field peak strength (TEFPS) were determined using terahertz pulsed imaging (TPI) and employed for the analysis of sustained-release coated pellets (theophylline layered sugar cores coated with Kollicoat SR:Kollicoat IR polymer blends). The effects of coating thickness, drug layer uniformity and optional...

During the process development of coated tablets, knowledge on the formation and the location of film coating 'weak spots' is a key factor to the success of the process and the resulting product batch. It is understood that the performance of the product batch may be greatly limited, and often compromised, by weak spots on the tablet film coat. Thi...

Applicability of a Terahertz Pulsed Spectroscopy (TPS) and a Terahertz Pulsed Imaging (TPI) for detection of tulobuterol (TBR) crystals in transdermal patches was investigated. Because TBR has high permeability in dermis, crystalline TBR in patch matrices contributes to controlling the release rate of TBR from a matrix. Therefore, crystalline TBR i...

The terahertz pulsed imaging (TPI) can be used successfully to determine the coating thickness of pharmaceutical products has been demonstrated. TPI nondestructively provides spatially resolved information from the surface of the tablet. The method used to generate terahertz pulsed radiation is based on illuminating a biased photoconductive switch...

The ability of terahertz pulsed imaging (TPI) to be employed as an analytical tool for monitoring a film coating unit operation and to assess the success of a subsequent process scale-up was explored in this study. As part of a process scale-up development, a total of 190 sustained-release tablets were sampled at 10% increments of the amount of pol...

The aim of this study was to investigate coating characteristics of push-pull osmotic systems (PPOS) using three-dimensional terahertz pulsed imaging (3D-TPI) and to detect physical alterations potentially impacting the drug release. The terahertz time-domain reflection signal was used to obtain information on both the spatial distribution of the c...

Terahertz technology seems set to become important in security screening and the pharmaceutical industry.

The solid-state terahertz (THz) spectrum (2–120cm−1) of α-form cyclotrimethylenetrinitramine (RDX) has been simulated using solid-state density functional calculations at a BP/DNP level of theory. BP/DNP features are in good agreement with both 298K and a new 7K polycrystalline RDX THz spectrum. The 7K RDX spectrum is noteworthy for several mode sh...

Pulsed terahertz attenuated total reflection (ATR) spectra of solid materials and liquids covering the 10 cm(-1) to 120 cm(-1) (0.3 THz to 3.6 THz) region of the electromagnetic spectrum are recorded using a terahertz pulsed spectrometer and silicon ATR modules. Pulsed terahertz ATR measurements are completed nondestructively using small amounts of...

Terahertz pulsed imaging (TPI) was evaluated for nondestructively characterizing the 3-D internal structures of pharmaceutical tablets. The structural information of a pharmaceutical tablet, such as coating thickness and interface uniformity, was obtained directly from the analysis of the time-domain terahertz waveform. The chemical map of a sample...

The potential of terahertz pulsed imaging (TPI) to predict the dissolution performance in sustained-release tablets was investigated in this study. Batches of coated tablets with similar weight gain during the coating process at the lab and pilot scales were subjected to non-destructive imaging by TPI and subsequently analysed by dissolution testin...

Delayed release dosage forms such as Asacol employ coatings that are engineered to breakdown and release the drug topically at the nominal pH of the lower intestinal tract. Asacol tablets were found to dissolve in an erratic fashion when they are dissolved in buffers below pH 7 which can occur naturally. In this study Terahertz pulsed imaging (TPI)...

Spectral distortions are commonly observed in terahertz spectra of granulated materials. These spurious structures in the spectroscopy are caused by scattering due to the refractive index mismatch between the particles and their surrounding medium. We find that the scattering contribution is random across sample positions and could be eliminated by...

The purpose of this research was to investigate suitable procedures for generating multivariate prediction vectors for quantitative composition and density analysis of intact solid oral dosage forms using terahertz pulsed imaging (TPI) spectroscopy. Both frequency- (absorbance and refractive index) and time-domain data are presented. A set of calib...

The purpose of this study was to investigate the dehydration of piroxicam monohydrate (PRXMH) in compacts using terahertz pulsed spectroscopy (TPS), Raman spectroscopy, and reflectance near-infrared (NIR) spectroscopy. Compacts were prepared by using PRXMH and poly(tetrafluoro)ethylene powders and combining them in three different manners before co...

The polymorphic modifications of carbamazepine show distinct spectral features in the far infrared between 2 and 130 cm^-1. Using time-resolved terahertz pulsed spectroscopy the enantiotropic solid state phase transition between two polymorphic forms was recorded. The terahertz spectra revealed that the solid state conversion follows a tw...

In this study, coating thickness and uniformity of production-scale pharmaceutical tablets were investigated using near-infrared (NIR) and terahertz pulse imaging (TPI) spectroscopy. Two coating formulations were considered; samples for each coating formulation were obtained at 0, 1, 2, 3, 4, and 5% coating weight. NIR spectra were collected, and r...

Pulsed terahertz attenuated total reflectance (ATR) spectroscopy is a simple, fast, and accurate method for acquiring far-infrared spectra of various materials. It was used to acquire terahertz spectra of pharmaceutical materials. The advantage of this technique is that it is nondestructive, allows transmission measurements of highly absorbing mate...

At the example of carbamazepine the crystallization of a small organic molecule from its amorphous phase was studied using in situ variable temperature terahertz pulsed spectroscopy (TPS). Even though terahertz spectra of disordered materials in the glassy state exhibit no distinct spectral features we demonstrate subtle changes in the spectra with...

Crystal lattice dynamics: By studying the low-energy intermolecular vibrational modes in the far-infrared region it is possible for the first time to resolve the two-step solid-state conversion mechanism in carbamazepine polymorphic forms III and I directly (see picture).

Various aspects of tablet coating quality were analysed with Terahertz pulsed imaging (TPI). Coating layer thickness variability and reproducibility, coating distribution and uniformity were determined and validated with optical microscopy imaging. Results indicated that TPI has the potential to be employed as a process analytical tool to determine...

Terahertz pulsed imaging is now used for routine non-destructive testing of pharmaceutical products. The technique provides valuable information about a tablet's coating uniformity and can provide additional information about its core. Terahertz pulsed spectroscopy is a powerful technique in the analysis of polymorphic forms as terahertz region of...

Terahertz pulsed imaging was used for non-destructively evaluating the critical quality attributes of pharmaceutical tablets including tablet coating integrity, coating thickness, tablet uniformity in three-dimension, and for identifying polymorphs.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

The coating quality of a batch of lab-scale, sustained-release coated tablets was analysed by terahertz pulsed imaging (TPI). Terahertz radiation (2 to 120 cm− 1) is particularly interesting for coating analysis as it has the capability to penetrate through most pharmaceutical excipients, and hence allows non-destructive coating analysis. Terahertz...

Terahertz pulsed spectroscopy was used to distinguish between different hydrate systems. In the example of four pharmaceutical materials lactose, carbamazepine, piroxicam and theophylline it was demonstrated that all different hydrate and anhydrate forms exhibit distinct spectra in the far infrared. Furthermore the dehydration of theophylline monoh...

Terahertz pulsed spectroscopy (TPS) and terahertz pulsed imaging (TPI) are two novel techniques for the physical characterization of pharmaceutical drug materials and final solid dosage forms, utilizing spectral information in the far infrared region of the electromagnetic spectrum. This review focuses on the development and performance of pharmace...

Three dimensional terahertz pulsed imaging (TPI) was evaluated as a novel tool for the nondestructive characterization of different solid oral dosage forms. The time-domain reflection signal of coherent pulsed light in the far infrared was used to investigate film-coated tablets, sugar-coated tablets, multilayered controlled release tablets, and so...

We have measured the terahertz absorption spectra of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), pentaerythritol tetranitrate (PETN), 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), 2,4,6-trinitrotoluene (TNT), the plastic explosives Semtex H, SX2, and Metabel, and a number of confusion materials using terahertz pulsed transmission spectrosc...

Good contrast is seen between normal tissue and regions of tumor in terahertz pulsed imaging of basal cell carcinoma (BCC). To date, the source of contrast at terahertz frequencies is not well understood. In this paper we present results of a spectroscopy study comparing the terahertz properties (absorption coefficient and refractive index) of exci...

The far-infrared properties of all five known polymorphic forms of the drug sulfathiazole have been studied by terahertz pulsed spectroscopy and low-frequency Raman spectroscopy. The observed spectra of the different polymorphs are distinctly different. Terahertz pulsed spectroscopy proves to be a rapid and complementary alternative to other physic...

The purpose of our research was to investigate efficient procedures for generating multivariate prediction vectors for quantitative chemical analysis of solid dosage forms using terahertz pulse imaging (TPI) reflection spectroscopy. A set of calibration development and validation tablet samples was created following a ternary mixture of anhydrous t...

Rigid molecule atomistic lattice dynamics calculations have been performed to predict the phonon spectra of the four polymorphs of carbamazepine, and these calculations predict that there should be differences in the spectra of all four forms. Terahertz spectra have been measured for forms I and III, and there are clearly different features between...

Studies of basal cell carcinoma using terahertz pulsed imaging have revealed a significant difference between regions of tumor and healthy tissue. These differences are manifested in the reflected pulse due to what is thought to be changes in refractive index and absorption. We present measurements of the refractive index and absorption coefficient...

In this study for the first time temperature dependent terahertz pulsed spectroscopy was performed on a pharmaceutical drug. The polymorphic conversion process of carbamazepine form III to I was studied at varying temperatures. Furthermore, the solid-state transformation at isothermal conditions below the melting point of carbamazepine was investig...

In this paper, we present the latest chemical mapping images of heterogeneous mixtures based on far-infrared reflection spectra obtained using a terahertz pulsed imaging system. The terahertz images and spectral data obtained have a spectral resolution of 1 cm−1 and cover a spectral range of 5–80 cm−1. This broad spectral coverage enables us to map...

The absorption spectrum of the explosive 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) has been measured using a conventional Fourier transform infrared spectroscopy and by terahertz pulsed spectroscopy. Seven absorption features in the spectral range of 5 - 120 cm(-1) have been observed and identified as the fingerprint of RDX. Furthermore, the spa...

Terahertz pulsed spectroscopy (TPS) is a new technique that is capable of eliciting rich information when investigating pharmaceutical materials. In solids, it probes long-range crystalline lattice vibrations and low energy torsion and hydrogen bonding vibrations. These properties make TPS potentially an ideal tool to investigate crystallinity and...

We report the use of a terahertz pulsed imaging technique for three-dimensional chemical mapping. Terahertz radiation reflected from a sample was measured pixel-by-pixel in time domain using a terahertz pulsed imaging system developed at TeraView Ltd, UK. The recorded terahertz waveforms were then transformed into frequency domain using time-partit...

An understanding of the finished structure of complex pharmaceutical coating is becoming desirable, because tablet coatings are now one of the preferred routes to control the release of active pharmaceutical ingredients. There are few nondestructive techniques capable of examining the coatings of compressed tablets; for example laser induced breakd...

The terahertz spectrum of the explosive RDX has been measured using a conventional Fourier transform infrared spectroscopy and by terahertz pulse spectroscopy in transmission and reflection modes. Seven absorption features in the spectral range 5-120 cm-1 have been observed and identified as the fingerprints of RDX explosive. Furthermore, a sample...

Studies in terahertz (THz) imaging have revealed a difference between diseased and healthy tissue in the THz regime. Since water has strong absorptions at THz frequencies, a likely contributing factor to the contrast mechanism is variation in water content. We have previously modelled the propagation of a THz waveform through water and normal skin...

The application of terahertz pulsed spectroscopy to polymorphic, liquid crystalline and amorphous forms of pharmaceutical compounds has been investigated. The different polymorphic forms of carbamazepine and enalapril maleate exhibit distinct terahertz absorbance spectra. In contrast to crystalline indomethacin and fenoprofen calcium, amorphous ind...

Recent events have led to dramatic changes to the methods employed in security screening. For example, following the failed shoe bombing, it is now common for shoes to be removed and X-rayed at airport checkpoints. There is therefore an increasing focus on new technologies that can be applied to security screening, either to simplify or speed up th...

The application of terahertz pulsed spectroscopy within the US Food and Drug Administration's (FDA's) recent process analytical technology (PAT) initiative is considered. As a case study the potency levels in paracetamol (4-acetamidophenol) and aspirin (acetylsalicylic acid) test tablets have been recovered from the terahertz absorption spectra usi...

Terahertz (THz) radiation lies between the infrared and microwave regions of the electromagnetic spectrum. Advances in THz technology have opened up many opportunities in this scientifically and technologically important spectroscopic region. The THz frequency range excites large amplitude vibrational modes of molecules as well as probing the weak...

The recent technological break-through of electromagnetic radiation sources, components and devices in the Terahertz (THz) region has triggered a variety of applications in the field of material science, biology and biomedicine. Biological applications are based on the specific spectroscopic fingerprints of biological matter in this spectral region...

The application of terahertz pulsed spectroscopy within the US Food and Drug Administration's (FDA's) recent process analytical technology (PAT) initiative is considered. As a case study the potency levels in paracetamol (4-acetamidophenol) and aspirin (acetylsalicylic acid) test tablets have been recovered from the terahertz absorption spectra usi...

Terahertz pulsed spectroscopy (TPS) is a recently developed quick, simple, and versatile technique for analyzing the chemical composition and physical form of a wide range of solid, liquid, and gaseous materials. Portable TPS systems using room temperature sources and detectors can now readily access the 'terahertz gap' with broadband coverage from...

We report the operation of a pulsed terahertz (THz) imaging system that uses a 120 fs pulse-width laser operating at 1.06 mum, and photoconductive InGaAs emitters and detectors. THz images are presented of biological and nonbiological specimens. The signal-to-noise ratio and frequency range of this system are compared to those obtained from existin...

Recent events have accelerated the quest for ever more effective security screening to detect an increasing variety of threats. Many techniques employing different parts of the electromagnetic spectrum from radio up to X- and gammaray are in use. Terahertz radiation, which lies between microwave and infrared, is the last part to be exploited for wa...