Elastic Measurements Research Articles

In-situ assessment of microscale crack tip fields in zirconium

High-resolution electron backscatter diffraction (HR-EBSD) can provide an estimate of elastic strains at a microscopic scale. Due to the need for high-quality Kikuchi patterns, HR-EBSD-based elastic studies have primarily been limited to the examination of small or residual strains. Due to this constraint, the scope for the use of HR-EBSD in the presence of large plastic deformation has not been extensively explored. In the present study, we investigate the elastic strain field in front of a plastically deforming crack by conducting an in-situ experiment inside a scanning electron microscope (SEM). Further, the experimental results are compared with crystal plasticity-based finite element (CPFE) simulations. A reasonable degree of qualitative similarity has been observed. Furthermore, the effect of a large strain floor on the relative elastic measurements is examined via simulations. A qualitative agreement has been observed in measuring relative elastic strains with or without a non-trivial strain floor, which rationalizes the effectiveness of relative elastic measurements in the presence of high applied strains.

Optical coherence elastography and its applications for the biomechanical characterization of tissues.

The biomechanical characterization of the tissues provides significant evidence for determining the pathological status and assessing the disease treatment. Incorporating elastography with optical coherence tomography (OCT), optical coherence elastography (OCE) can map the spatial elasticity distribution of biological tissue with high resolution. After the excitation with the external or inherent force, the tissue response of the deformation or vibration is detected by OCT imaging. The elastogram is assessed by stress-strain analysis, vibration amplitude measurements, and quantification of elastic wave velocities. OCE has been used for elasticity measurements in ophthalmology, endoscopy, and oncology, improving the precision of diagnosis and treatment of disease. In this article, we review the OCE methods for biomechanical characterization and summarize current OCE applications in biomedicine. The limitations and future development of OCE are also discussed during its translation to the clinic.

Pincus blob elasticity in an intrinsically disordered protein.

Understanding the dynamic structure of intrinsically disordered proteins (IDPs) is important to deciphering their biological functions. Here, we exploit precision entropic elasticity measurements to infer the conformational behavior of a model IDP construct formed from the disordered tail of the neurofilament low molecular weight protein. The IDP construct notably displays a low-force power-law elastic regime, consistent with the Pincus blob model, which allows direct extraction of the Flory exponent, [Formula: see text], from the force-extension relationship. We find [Formula: see text] increases with added denaturant, transitioning from a nearly ideal chain to a swollen chain in a manner quantitatively consistent with measurements of IDP dimensions from other experimental techniques. We suggest that measurements of entropic elasticity could be broadly useful in the study of IDP structure.

Laser Triangulation Based In-Line Elastic Recovery Measurement for the Determination of Ribbon Solid Fraction in Roll Compaction

Process Analytical Technology (PAT) plays a crucial role in the design of today's manufacturing lines as continuous manufacturing becomes more important. Until now PAT tools to measure the ribbon solid fraction (SFribbon) in-line are not commonly used in roll compaction. The aim of this study was therefore to establish a new approach as PAT for in-line ribbon solid fraction determination. Different placebo formulations with different binders and one formulation containing active pharmaceutical ingredient were investigated using in-line laser triangulation measurement to detect the ribbon thickness after compaction. With this the ribbon elastic recovery was determined in-line (ERin−line) while the ribbons are attached to the roll surface. It was found that the ratio (ERratio) between the total elastic recovery and ERin−line is formulation specific and not influenced by any process parameters. This enables ERratio as prediction tool for SFribbon, if the solid fraction at gap (SFgap) width is known. SFgap was determined with ribbon mass flow measurement or based on the Midoux model, a simplified Johanson model, gaining two prediction models for SFribbon. Both models showed good agreement of the predicted SFribbon and the measured one.

An improved inversion method for shale elastic parameters measurement based on ultrasonic resonance spectroscopy

The accurate measurement of elastic parameters of shale cores has important guidance for the exploration and development of shale oil and gas. The traditional shale acoustic experiment requires multiple samples from different angles and its preparation process is complex. Resonant Ultrasound Spectroscopy has the advantages of repeatable measurement, high accuracy, and the ability to obtain all elastic parameters from a single small sample. However, the influence of clamping force and measuring angle needs comprehensive analysis to ensure that formant can be measured as many and accurately as possible. This research first conducts sensitivity analysis on the elastic parameters of different shale to guide the experiment. In addition, due to the more complex inversion objective function of the anisotropic shale compared to isotropic samples, the traditional Levenberg–Marquardt method has a strong dependence on the initial value and is prone to falling into local optimal solution. The L-BFGS (limited memory BFGS) method is introduced into the inversion of anisotropic elastic parameters of shale, which can significantly improve the inversion efficiency. Finally, the robustness and reliability of the inversion method are validated through theoretical and experimental measurement results. [Work supported by the National Natural Science Foundation of China (42004117 and 42127807).]

Preliminary Investigation of Normal Pancreas Elasticity using Point Shear Wave Elastography.

Point shear wave elastography (pSWE) is used to provide quantitative information about the elasticity of the tissues. It has been used in many clinical applications to identify diseases early. This study aims to assess the suitability of pSWE to evaluate pancreas tissue stiffness and provide normal reference values for healthy pancreas tissues. This study was conducted in the diagnostic department at a tertiary care hospital between October and December 2021. Sixteen healthy volunteers (eight men and eight women) participated. Pancreas elasticity measurements were obtained in different regions of interest (head, body, and tail). Scanning was performed by a certified sonographer using Philips EPIC7 ultrasound systems (Philips Ultrasound; Bothel, WA, USA). The mean velocity of the head of the pancreas was 1.3 ± 0.3 m/s (median: 1.2 m/s), the body was 1.4 ± 0.3 m/s (median: 1.4 m/s), and the tail was 1.4 ± 0.4 m/s (median: 1.2 m/s). The mean dimension was 17 ± 3 mm, 14 ± 4 mm, and 14 ± 6 mm for the head, body, and tail. The correlation of pancreas velocity across different segments and dimensions shows no significant difference with p values of 0.39 and 0.11, respectively. This study shows that assessing the elasticity of the pancreas using pSWE is possible. A combination of SWVs measurements and dimensions could provide an early evaluation of pancreas status. Further studies including pancreatic disease patients are recommended.

An analysis of the regional heterogeneity in tissue elasticity in lung cancer patients with COPD.

Recent advancements in obtaining image-based biomarkers from CT images have enabled lung function characterization, which could aid in lung interventional planning. However, the regional heterogeneity in these biomarkers has not been well documented, yet it is critical to several procedures for lung cancer and COPD. The purpose of this paper is to analyze the interlobar and intralobar heterogeneity of tissue elasticity and study their relationship with COPD severity. We retrospectively analyzed a set of 23 lung cancer patients for this study, 14 of whom had COPD. For each patient, we employed a 5DCT scanning protocol to obtain end-exhalation and end-inhalation images and semi-automatically segmented the lobes. We calculated tissue elasticity using a biomechanical property estimation model. To obtain a measure of lobar elasticity, we calculated the mean of the voxel-wise elasticity values within each lobe. To analyze interlobar heterogeneity, we defined an index that represented the properties of the least elastic lobe as compared to the rest of the lobes, termed the Elasticity Heterogeneity Index (EHI). An index of 0 indicated total homogeneity, and higher indices indicated higher heterogeneity. Additionally, we measured intralobar heterogeneity by calculating the coefficient of variation of elasticity within each lobe. The mean EHI was 0.223 ± 0.183. The mean coefficient of variation of the elasticity distributions was 51.1% ± 16.6%. For mild COPD patients, the interlobar heterogeneity was low compared to the other categories. For moderate-to-severe COPD patients, the interlobar and intralobar heterogeneities were highest, showing significant differences from the other groups. We observed a high level of lung tissue heterogeneity to occur between and within the lobes in all COPD severity cases, especially in moderate-to-severe cases. Heterogeneity results demonstrate the value of a regional, function-guided approach like elasticity for procedures such as surgical decision making and treatment planning.

Preparation, nano-mechanics and particle deposition behavior of thin, antifouling hydrogel coatings

Hydrogels based on hydrophilic, crosslinked polymer networks can reduce surface contamination in aqueous environments and continue attracting research interest due to their low adhesion, biocompatibility and tunable properties. In particular, sub-micron hydrogel films can potentially screen a surface from interaction with foulant colloids and microorganisms without compromising original functions, such as water permeation in membranes. This study focuses on the preparation of thin hydrogel films with the goal of understanding their adhesive and micromechanical properties, as well as factors affecting the dynamics of microparticle deposition on such films, mimicking the initial stages of surface fouling with colloids, microparticles and microorganisms. For this purpose, a simple procedure was developed to simultaneously crosslink and covalently anchor multi-arm-PEG precursors to a surface to form a submicron coating as a representative model. The effects of synthetic parameters and external conditions on adhesion and viscoelasticity were studied by force spectroscopy using polystyrene colloidal probes. The same particles were also employed in macroscopic deposition experiments in a parallel plate flow cell under identical solution conditions. Microscopic adhesion and elasticity were unaffected by the hydrogel crosslinking density and by salinity, but strongly affected by solution pH and dwell time, whereas macroscopic deposition was strongly affected both by salinity and by pH. These differences were ascribed to the effect of long-range double-layer forces, involved in deposition but absent in measurements of adhesion and elasticity. The results highlight the differences and similarities between the two types of measurements and underlying phenomena, as a step towards the understanding and rational design of soft antifouling coatings.

Reliability of lower leg muscle elasticity using shear wave elastography in non-weight-bearing and weight-bearing

PurposeMuscle elasticity can be quantified with shear wave elastography (SWE) and has been used as an estimate of muscle force but reliability has not been established for lower leg muscles. The purpose of this study was to examine the intra-rater and inter-rater reliability of elasticity measures in non-weight-bearing (NWB) and weight-bearing (WB) for the tibialis anterior (TA), tibialis posterior (TP), peroneal longus (PL), and peroneal brevis (PB) muscles using SWE. MethodsA total of 109 recreationally active healthy adults participated. The study employed a single-cohort, same-day repeated-measures test–retest design. Elasticity, measured in kilopascals as the Young’s modulus, was converted to the shear modulus. All four muscles were measured in NWB and at 90% WB. ResultsIntra-rater reliability estimates were good to excellent for NWB (ICC = 0.930–0.988) and WB (ICC = 0.877–0.978) measures. Inter-rater reliability estimates were moderate to good (ICC = 0.500–0.795) for NWB measures and poor to good (ICC = 0.346–0.910) for WB measures. ConclusionDespite the studies poor to good inter-rater variability, the intra-rater reproducibility represents the potential benefit of SWE in NWB and WB. Establishing the reliability of SWE with clinical and biomechanical approaches may aid in improved understanding of the mechanical properties of muscle.

Immersion ultrasound improves the repeatability of shear-wave elastography for measuring median nerve elasticity

ObjectiveTo study the factors that influence the measurement of median nerve elasticity, to provide a more reproducible test for the assessment of median nerve elasticity using shear wave elasticity (SWE), and to reduce operator empirical dependence. To compare the repeatability of the median nerve elasticity measurement using immersion SWE with that using contact SWE, analyze the factors affecting SWE measurement, and provide a more repeatable method for doctors without SWE operation experience.MethodsTwo doctors without SWE operation experience measured the median nerve mean elastic modulus (Emean) at the same position and at different time points on the right wrist of 58 healthy volunteers using immersion and contact ultrasound methods. The intraobserver and interobserver repeatability of measurements was assessed using the interclass correlation coefficient (ICC), while the repeatability was assessed using the Bland–Altman diagram.ResultsThe intraobserver and interobserver repeatability of the median nerve elasticity measured via contact SWE by inexperienced operators were classified as good, with ICCs of 0.633 (95% CI 0.380–0.783) and 0.552 (95% CI 0.243–0.735), respectively. The intraobserver and interobserver repeatability of the median nerve elasticity measured by immersion SWE were very good, with ICCs of 0.975 (95% CI 0.958–0.985) and 0.942 (95% CI 0.902–0.966), respectively. The intraobserver and interobserver Bland–Altman diagram of median nerve elasticity measured by immersion SWE showed that 98% of the points fell within the 95% limits of agreement. The intraobserver and interobserver Bland–Altman diagram of median nerve elasticity measured by contact SWE showed that 94% of the points fell within the 95% limits of agreement.ConclusionImmersion ultrasound can improve the repeatability of median nerve elasticity measurements by inexperienced operators.

Multiscale mechanical analysis of the elastic modulus of skin

The mechanical properties of the skin determine tissue function and regulate dermal cell behavior. Yet measuring these properties remains challenging, as evidenced by the large range of elastic moduli reported in the literature—from below one kPa to hundreds of MPa. Here, we reconcile these disparate results by dedicated experiments at both tissue and cellular length scales and by computational models considering the multiscale and multiphasic tissue structure. At the macroscopic tissue length scale, the collective behavior of the collagen fiber network under tension provides functional tissue stiffness, and its properties determine the corresponding elastic modulus (100–200 kPa). The compliant microscale environment (0.1–10 kPa), probed by atomic force microscopy, arises from the ground matrix without engaging the collagen fiber network. Our analysis indicates that indentation-based elasticity measurements, although probing tissue properties at the cell-relevant length scale, do not assess the deformation mechanisms activated by dermal cells when exerting traction forces on the extracellular matrix. Using dermal-equivalent collagen hydrogels, we demonstrate that indentation measurements of tissue stiffness do not correlate with the behavior of embedded dermal fibroblasts. These results provide a deeper understanding of tissue mechanics across length scales with important implications for skin mechanobiology and tissue engineering. Statement of SignificanceMeasuring the mechanical properties of the skin is essential for understanding dermal cell mechanobiology and designing tissue-engineered skin substitutes. However, previous results reported for the elastic modulus of skin vary by six orders of magnitude. We show that two distinct deformation mechanisms, related to the tension–compression nonlinearity of the collagen fiber network, can explain the large variations in elastic moduli. Furthermore, we show that microscale indentation, which is frequently used to assess the stiffness perceived by cells, fails to engage the fiber network, and therefore cannot predict the behavior of dermal fibroblasts in stiffness-tunable fibrous hydrogels. This has important implications for how to measure and interpret the mechanical properties of soft tissues across length scales.

Role of Endoscopic Ultrasound in Predicting Solid Pancreatic Lesions Using Strain Ratio and Elastography.

Despite advancement in imaging techniques, the diagnosis of solid pancreatic lesions (SPLs) remains challenging. The latest advancement in elastography permits the quantitative measurements of the average elasticity of a lesion. Therefore, our main aim of this study was to determine the utility of endoscopic ultrasound-guided elastography (EUS-EG) and strain ratio (EUS-SR) in predicting SPLs. This cross-sectional study was performed at the Department of Hepatogastroenterology, Sindh Institute of Urology and Transplantation. All patients with radiological diagnosis of SPLs underwent EUS-EG, followed by strain ratio (SR) measurement and targeted pancreatic fine needle lesion biopsy (FNB). Area under the receiver operating curve (AUROC) was obtained for SR and combined elastography and SR and at an optimal cutoff, diagnostic accuracy was obtained in predicting the nature of SPLs. A total of 52 patients were included in this study. Out of them, 32 (61.5%) patients were males while 20 (38.5%) were females. The mean age was 50.8 ± 12.5 years. Twenty-four (46.2%) patients had malignant pancreatic lesions. Among malignant lesions, the most common etiology was pancreatic adenocarcinoma seen in 18 (34.6%) patients. Out of 28 (53.8%) patients with benign lesions, 14 (26.9%) patients had inflammatory disease. Area under the receiver operating curve was obtained for both SR alone and SR combined with elastography score in differentiating benign from malignant SPLs which was 0.832 (p-value < 0.001) for SR alone and a slightly higher for combined SR with elastography (AUROC-0.839)(p-value < 0.001). At an optimal cutoff of SR of >17, the sensitivity was 94.8% and the diagnostic accuracy was 74% in predicting SPLs. While, when SR and elastography were combined together, the sensitivity increased to 96% with a diagnostic accuracy of 75%. Combined EUS-EG and SR were accurate in diagnosing malignant pancreatic lesions with a diagnostic accuracy of 75% providing additional diagnostics information before biopsy. However, multicentric studies with larger sample sizes are required for the validation of our results to determine the utility and diagnostic accuracy of EUS-SR in defining the characteristic of pancreatic lesions. Bajaj K, Yaseen T, Tasneem AA, et al. Role of Endoscopic Ultrasound in Predicting Solid Pancreatic Lesions Using Strain Ratio and Elastography. Euroasian J Hepato-Gastroenterol 2023;13(1):1-4.

Elastic strain field measurements in the TEM for metallurgical applications

In the last twenty years, several transmission electron microscopy techniques have been developed to measure nanoscale elastic strain fields, but with very little applications to metals and alloys. Here, we show that scanning precession electron diffraction can be used to measure elastic strain fields induced by nanometric coherent particles in an aluminium alloy. The agreement with theory is excellent, despite small discrepancies very near the particle. Strains are examined in both cartesian and cylindrical coordinate systems. Examination of the radial strains around the particle reveals that the deformation mode in the matrix is close to plane-strain. This results from having prepared samples as thin foils, which is required for observation in the microscope. Plane strain implies that only a partial information about the strain field in the bulk material is available, but it ensures that the measurements are not disturbed by variations of strain through the foil thickness. Strategies for ensuring plane strain in future observations are discussed at the end of the paper.

Mechanical Properties of Uncured Thermoset Tow Prepreg: Experiment and Finite Element Analysis

This paper presents an experimental analysis of the tensile behavior of unidirectional carbon/epoxy prepreg, focusing on the nonlinearity observed at the beginning of the stress–strain curve. Due to the material’s high viscosity, securely holding specimens during testing was challenging, prompting modifications in the gripping method to ensure reliable data. By using a longer gauge length, the slippage impact on elastic modulus measurement was minimized, resulting in good repeatability among the test samples. Experimental findings highlighted the significant interaction between fiber waviness and the viscous matrix, leading to stiffness reduction. The linear stiffness of the samples closely matched that of the fibers and remained unaffected by temperature variations. However, at higher temperatures, the epoxy matrix’s decreased viscosity caused an upward shift in the stiffness plot within the non-linear region. To support the experimental findings, a micromechanical model of prepreg tow with fiber waviness was proposed. An RVE model of periodically distributed unidirectional waved cylindrical fibers embedded within the matrix was developed to predict effective material stiffness parameters. The simulation outcomes aligned well with the uniaxial tensile test of the prepreg tow, demonstrating the proposed RVE model’s capability to accurately predict elastic properties, considering factors like fiber arrangement, waviness, and temperature.

Automatic elasticity measurement of single cells using a microfluidic system with real-time image processing.

The mechanical properties of cells are closely related to their physiological states and functions. Due to the limitations of conventional cell elasticity measurement technologies such as low throughput, cell-invasiveness, and high cost, microfluidic systems are emerging as powerful tools for high-throughput cell mechanical property studies. This paper introduces a microfluidic system to automatically measure the elastic modulus of single cells in real time. The system integrated a microfluidic chip with a microchannel for cell constriction, a pressure pump, a precision differential pressure sensor, and a program for online analysis of cell deformation. The program used a fast U-net to segment cell images and measure protrusion length during cell deformation. Subsequently, the cell elasticity was determined in real-time based on the deformation and required pressure using the power law rheological model. Finally, Young's modulus of BMSCs, Huh-7 cells, EMSCs, and K562 cells was measured as 25.13 ± 15.19 Pa, 69.74 ± 92.01 Pa, 54.50 ± 59.31 Pa and 58.43 ± 27.27 Pa, respectively. The microfluidic system has significant application potential in the automated evaluation of cell mechanical properties.Clinical Relevance-The technique in this paper may be used for the automatic and high throughput study of the stiffness of cells, such as stem cells and cancer cells. The stiffness data may contribute to stem cell therapy and cancer research.

Residual elastic strain and survivability of stabilized zirconia coated carbon-carbon (C/C) composite

Carbon-carbon (C/C) composites require protective coatings for prolonged use in elevated temperature, oxidizing environments. Ceramic coatings can provide oxidation protection; however, thermal expansion mismatch in conjunction with thermal events and interfacial constraint during coating deposition can result in residual stress, which can affect the lifetime and performance of the system. This work leveraged high energy synchrotron X-ray diffraction to determine the depth resolved residual elastic strain in two rare-earth oxide stabilized zirconia (12 mol% yttria and 6 mol% samaria) coatings, applied to a carbon-carbon composite substrate. The experimental characterization of the as-deposited coatings indicated a tension to compression residual elastic strain gradient, which was consistent with an energy-based model that illustrated the crystal structure dependence of the residual stress state. Via an oxyacetylene torch exposure, the ablation behavior and crack propagation were correlated to the measured residual elastic strain state and highlighted the influence of processing and exposure induced residual stress on coating performance. These experimental residual elastic strain measurements and relation to failure mechanisms support the survivability of these coating systems in applications that require thermal protection systems (TPS).

Exploring the anatomical factors influencing testes elasticity via ultrasound shear wave elastography: Preliminary results

PurposeThe aim of this study is to evaluate the anatomical factors influencing elasticity values of normal testicular parenchyma using shear wave elastography (SWE). MethodsThis study examined 68 healthy male volunteers (117 testes in which standard transverse axis ultrasonography views could be obtained) via conventional scrotal ultrasonography and SWE. Both the mean (EMean) and standard deviation (ESD) elasticity values were acquired. ResultsIn the standard transverse axis view of the rete testis at the mid-lateral edge of the testes, the EMean values in 2mm the testicular parenchyma from the rete testis and the testicular capsule at the same level as the rete testis were all significantly larger than in the central zone (P<0.001, P<0.001, respectively). The EMean value in the testicular parenchyma 2mm from the testicular capsule on the line formed approximately 45° below the horizontal line of the rete testis was significantly larger than in the rete testis approximately 45° above the horizontal line (P<0.001). In two standard transverse axis views, the ESD values in other regions were significantly larger than those in the central zones (all P<0.001). Also, the EMean values in the transmediastinal arteries were larger than those of the surrounding normal testicular parenchyma (P<0.001). ConclusionBased on SWE, factors including the testicular capsule, the density of testicular fibrous septa, the depth of the Q-Box™, and the transmediastinal artery may influence the testes elasticity measurement.

DIELECTRIC SPECTROSCOPY METHOD FOR POLAR POLYMERS ELASTIC PROPERTIES DIAGNOSTICS

The mechanical properties of polymer materials are changes under the complex influence of such climatic factors as, for example, solar radiation, temperature changes, high humidity, and the impact of microorganisms – destructors. The methods of non-invasive diagnostics have to be used for changes prediction of the polymers materials products mechanical properties. The dielectric spectroscopy possibility using for diagnosing the modulus of elasticity of polymeric materials is considered in that paper. The results of elasticity modulus investigation by the dielectric spectroscopy using the DiMarzio–Bishop model and the mechanical measurements method are considered and compared in that paper. The results of dielectric and mechanical properties of polymers samples (polymethylmethacrylate, polycarbonate and polyvinylchloride) investigation are considered in that paper. These polymers are polar, so their mechanical properties in the elastic region of deformations can be investigate by dielectric spectroscopy method. This is due to the fact that the elastic deformations of a polymer are determined by the deformation of its macromolecules. It is show, that there are qualitative agreements between results of that measurement and the DiMarzio–Bishop model have to be refinement. The dipoles are represented as a spheres and interaction between dipoles are neglected in the DiMarzio–Bishop model. In our opinion, the interaction between dipoles in polymeric macromolecules is inevitable, and the configuration of dipoles differs from spherical. The necessity of using the calibration coefficient in the DiMarzio–Bishop model is shown by comparing the results of elastic modulus experimental measurements by the mechanical method and the dielectric spectroscopy method. This calibration factor takes into account the average number of dipoles in a macromolecule with a coefficient proportionality ∼6,7⋅10–5.

Forward Looking Exporters

This paper studies the role of expectations in driving export adjustment. We assemble bilateral data on spot exchange rates, one year ahead exchange rate forecasts and HS2-product export data for 11 exporting countries and 64 destinations, covering the 2006–2014 period. Results from fixed effects regressions and an instrumental variables approach show that expectations of exchange rate changes are an important channel for export adjustment. A one percent expected exchange rate depreciation over the next year is associated with a 0.96 percent increase in the extensive margin (entry of new exporters) in the 2SLS regression, with statistically insignificant effects on total exports or the intensive margin. We provide intuition for these findings with a simple model with heterogeneous firms and sticky prices, and use our model to discuss the implications of anticipation for subsequent export growth and trade elasticity measurement.

Insights Into Vascular Physiology From Sleep Photoplethysmography.

Photoplethysmography (PPG) in consumer sleep trackers is now widely available and used to assess heart rate variability (HRV) for sleep staging. However, PPG waveform changes during sleep can also inform about vascular elasticity in healthy persons who constitute a majority of users. To assess its potential value, we traced the evolution of PPG-pulse waveform during sleep alongside measurements of HRV and blood pressure. Seventy eight healthy adults (50% male, median (range) age: 29.5 (23.0, 43.8)) underwent overnight polysomnography (PSG) with fingertip PPG, ambulatory blood pressure monitoring (ABPM) and electrocardiography (ECG). Selected PPG features that reflect arterial stiffness: systolic to diastolic distance (∆T_norm), normalized rising slope (Rslope) and normalized reflection index (RI) were derived using a custom-built algorithm. Pulse arrival time (PAT) was calculated using ECG and PPG signals. The effect of sleep stage on these measures of arterial elasticity and how this pattern of sleep stage evolution differed with participant age were investigated. Blood pressure, heart rate and PAT were reduced with deeper non-REM sleep but these changes were unaffected by the age range tested. After adjusting for lowered heart rate, ∆T_norm, Rslope and RI showed significant effects of sleep stage, whereby deeper sleep was associated with lower arterial stiffness. Age was significantly correlated with the amount of sleep-related change in ∆T_norm, Rslope and RI, and remained a significant predictor of RI after adjustment for sex, body mass index, office blood pressure and sleep efficiency. The current findings indicate that the magnitude of sleep-related change in PPG waveform can provide useful information about vascular elasticity and age effects on this in healthy adults.