Noninvasive Measurement Research Articles

Correlation between the Ocular Surface Disease Index and dry eye functional parameters measured with the OCULUS Keratograph 5M in a Hispanic population

Abstract Background: The evaluation of dry eye disease (DED) and the ocular surface can be approached from patient-centered questionnaires, clinical scales using the slit-lamp microscope, and more recently innovative ophthalmological devices that allow for noninvasive tests. The OCULUS Keratograph 5M (K5M) is a device that allows for noninvasive measurement of ocular surface parameters. Materials and Methods: The present article is a retrospective and observational study detailing the correlation of the OCULUS K5M surface parameters and the Ocular Surface Disease Index (OSDI) score. Patients of any gender and age attending a cornea and refractive surgery practice in an academic center underwent a full ophthalmological examination and tear meniscus height, tear breakup time, bulbar redness, meibography, and OSDI score measurement through the K5M. Results: One hundred and sixty-four eyes of 82 patients were included. The sample showed a female preponderance (78%) and a mean age of 49.45 years. When comparing the OSDI score with ocular surface parameters, a weak negative correlation was found with the tear meniscus height (Pearson coefficient: [ −0.229, P = 0.003]). There were no other statistically significant correlations between the K5M and the OSDI score. In addition, the meibomian gland dropout was significantly associated with increasing age, whereas conjunctivochalasis was associated with the female gender, increasing age and increasing OSDI score. Conclusions: The subjective symptoms of DED measured with OSDI score correlate only with tear meniscus height measured by the K5M in a Hispanic population. The detection of symptomatic DED patients through the K5M is incomplete in this population.

Use of noninvasive measurement of the indocyanine green plasma disappearance rate in patients with septic shock.

Our aim was to analyse the relation between serial values of the indocyanine green plasma disappearance rate (ICG-PDR) with hospital mortality in the first 48 hours of ICU admission in patients with septic shock. A prospective observational study was carried out over 12 months of patients admitted to the ICU with septic shock. Each patient underwent noninvasive determination of ICG-PDR at 24 and 48 hours with the LiMON® module. Follow-up was performed until hospital discharge or exitus. 63 patients. Age 61.1±12.3 years. 60.3% men. SOFA score on admission 8.7±3.3, APACHE II score was 27.9±10.7 points. A total of 44.4% of patients died. The ICG-PDR values in the first 24 hours of ICU admission were lower in nonsurvivors: 10.5 (5.7-13.0)%/min vs. 15.9 (11.4-28.0)%/min, p <0.001. Furthermore, in nonsurvivors, there was no improvement in ICG-PDR between 24 h and 48 h, while in survivors, there was an increase of 25%: 15.9 (11.4-28.0)%/min and 20.9 (18.0-27.0)%/min, p=0.020. The silhouette measure of ICG-PDR cohesion and separation for the clusters analysed (nonsurvivors and survivors) was satisfactory (0.6). ICG-PDR<11.7%/min was related to in-hospital mortality, ICG-PDR> 18%/min to survival, and the interval between 11.7% and 18%/min covered a range of uncertainty. In the two-stage cluster, ICG-PDR, SOFA and APACHE II present satisfactory predictive scores 24 hours after patient admission. ICG-PDR in our setting is a useful clinical prognostic tool and could optimise the decision tree in patients with septic shock.

A Novel Protection and Repair Skincare Regimen Shows Efficacy for Improving Environmental Skin Aging.

Skin aging is accelerated by environmental exposures including solar radiation and pollutants. Thus, protecting skin from environmental exposure and repairing ensuing damage is essential for keeping skin healthy and appearing youthful. To evaluate the clinical benefits of a novel skincare regimen designed to provide comprehensive environmental protection in the daytime and repair environmentally damaged skin at night. Thirty participants, including males and females, with mild-to-moderate extrinsic aging, were enrolled in a 12-week single-site study. Participants used the regimen (The Essential Six, RATIONALE, Victoria, Australia) comprised of 3 products to protect the skin in the morning and 3 products to repair the skin at night. Participants were seen at baseline and evaluated for efficacy and tolerability at weeks 2, 6, and 12. Non-invasive measurements to evaluate hydration, transepidermal water loss, skin tone, and elasticity were conducted. The dermatologist investigator noted across-the-board improvement in all evaluated parameters, except deep wrinkles. By week 12, there were statistically significant (P&lt;0.001) improvements in radiance (43%), tactile roughness (48%), visual roughness (44%), firmness (32%), clarity/even skin tone (21%), and overall appearance (29%). Fine lines improved 16% at week 12 (P=0.002). Participant self-assessment revealed statistically significant and progressive improvement in all evaluated parameters over time. No tolerability issues were identified by the investigator, while a small number of participants reported mild stinging and some dryness that resolved over time. This was likely due to the high concentration of active ingredients found in this regimen. Corneometry revealed improved skin hydration of 28% as early as week 2. The data presented confirms that this novel protection and repair regimen improves the appearance of environmentally aged skin. J Drugs Dermatol. 2024;23(10):866-872. doi:10.36849/JDD.8274.

Validation of a Commercial ELISA Kit for Non-Invasive Measurement of Biologically Relevant Changes in Equine Cortisol Concentrations

The measurement of fecal cortisol/corticosterone metabolites (FCMs) is often used to quantify the stress response. The sampling method is relatively non-invasive, reduces concern for elevation of cortisol from the sampling method, and has been shown to measure cortisol more consistently without the daily diurnal rhythm observed in blood. Commercial ELISA (enzyme-linked immunoassay) kits offer benefits over previously validated immunoassay methods but lack validation. The objective of this study was to evaluate a commercial ELISA kit (Arbor AssaysTM DetectX® Cortisol ELISA kit, K003-H1, Ann Arbor, MI, USA) and provide analytical and biologic validation of equine fecal and plasma samples. Horses (4 male, 4 female, mean ± SD: 4 ± 5 yr) were transported for 15 min with limited physical and visual contact via a livestock trailer. Blood and fecal samples were collected pre- and post-transportation. Parallelism, accuracy, and precision tests were used to analytically validate this kit. Data were analyzed using PROC MIXED in SAS 9.4. Plasma cortisol concentrations increased in response to trailering (254.5 ± 26.4 nmol/L, 0 min post-transportation) compared to pre-transportation (142.8 ± 26.4 nmol/L). FCM concentrations increased 24 h post-trailering (10.8 ± 1.7 ng/g) when compared to pre-transportation (7.4 ± 1.7 ng/g). These data support that changes in FCMs can be observed 24 h post-stressor. In conclusion, the Arbor AssaysTM DetectX® Cortisol ELISA kit is a reliable, economic option for the measurement of biologically relevant changes in cortisol in equine plasma and FCMs.

S2243 Correlation of Non-Invasive Measurement With Gross Measurement of Small Bowel Length: A Meta-Analysis

S2243 Correlation of Non-Invasive Measurement With Gross Measurement of Small Bowel Length: A Meta-Analysis

In silico data-based comparison of the accuracy and error source of various methods for noninvasively estimating central aortic blood pressure

Background and objectivesThe higher clinical significance of central aortic blood pressure (CABP) compared to peripheral blood pressures has been extensively demonstrated. Accordingly, many methods for noninvasively estimating CABP have been proposed. However, there still lacks a systematic comparison of existing methods, especially in terms of how they differ in the ability to tolerate individual differences or measurement errors. The present study was designed to address this gap. MethodsA large-scale ‘virtual subject’ dataset (n = 600) was created using a computational model of the cardiovascular system, and applied to examine several classical CABP estimation methods, including the direct method, generalized transfer function (GTF) method, n-point moving average (NPMA) method, second systolic pressure of periphery (SBP2) method, physical model-based wave analysis (MBWA) method, and suprasystolic cuff-based waveform reconstruction (SCWR) method. The errors of CABP estimation were analyzed and compared among methods with respect to the magnitude/distribution, correlations with physiological/hemodynamic factors, and sensitivities to noninvasive measurement errors. ResultsThe errors of CABP estimation exhibited evident inter-method differences in terms of the mean and standard deviation (SD). Relatively, the estimation errors of the methods adopting pre-trained algorithms (i.e., the GTF and SCWR methods) were overall smaller and less sensitive to variations in physiological/hemodynamic conditions and random errors in noninvasive measurement of brachial arterial blood pressure (used for calibrating peripheral pulse wave). The performances of all the methods worsened following the introduction of random errors to peripheral pulse wave (used for deriving CABP), as characterized by the enlarged SD and/or increased mean of the estimation errors. Notably, the GTF and SCWR methods did not exhibit a better capability of tolerating pulse wave errors in comparison with other methods. ConclusionsClassical noninvasive methods for estimating CABP were found to differ considerably in both the accuracy and error source, which provided theoretical evidence for understanding the specific advantages and disadvantages of each method. Knowledge about the method-specific error source and sensitivities of errors to different physiological/hemodynamic factors may contribute as theoretical references for interpreting clinical observations and exploring factors underlying large estimation errors, or provide guidance for optimizing existing methods or developing new methods.

FMRI speech tracking in primary and non-primary auditory cortex while listening to noisy scenes

Invasive and non-invasive electrophysiological measurements during “cocktail-party”-like listening indicate that neural activity in the human auditory cortex (AC) “tracks” the envelope of relevant speech. However, due to limited coverage and/or spatial resolution, the distinct contribution of primary and non-primary areas remains unclear. Here, using 7-Tesla fMRI, we measured brain responses of participants attending to one speaker, in the presence and absence of another speaker. Through voxel-wise modeling, we observed envelope tracking in bilateral Heschl’s gyrus (HG), right middle superior temporal sulcus (mSTS) and left temporo-parietal junction (TPJ), despite the signal’s sluggish nature and slow temporal sampling. Neurovascular activity correlated positively (HG) or negatively (mSTS, TPJ) with the envelope. Further analyses comparing the similarity between spatial response patterns in the single speaker and concurrent speakers conditions and envelope decoding indicated that tracking in HG reflected both relevant and (to a lesser extent) non-relevant speech, while mSTS represented the relevant speech signal. Additionally, in mSTS, the similarity strength correlated with the comprehension of relevant speech. These results indicate that the fMRI signal tracks cortical responses and attention effects related to continuous speech and support the notion that primary and non-primary AC process ongoing speech in a push-pull of acoustic and linguistic information.

Anogenital distance and the risk of Late-onset hypogonadism

Objective: to investigate the association between anogenital distance (AGD) and the risk of Late-onset Hypogonadism (LOH). Methods: We prospectively recruited 145 consecutive patients referred for transrectal prostate biopsy due to prostate-specific antigen (PSA) elevation or abnormal digital rectal examination, between September 2019 and December 2021. Two variants of AGD, anus to scrotum base (AGDas) and anus to dorsal insertion of penis (AGDap) were measured. Serum total testosterone levels in fasting conditions between 07.00 and 11.00 h were determined. Patients filled out the Aging Males’ Symptoms (AMS) scale questionnaire. Results: LOH was diagnosed in 29% of the participants and presented both AGDs shorter than men without LOH, with an AGDap of 116.09 mm (9.02 mm) versus 128.71 (10.76), and an AGDas 29.70 (8.01) versus 39.93 (11.64); both p &lt; 0.05. ANCOVA test showed a significant association between the presence of LOH and both AGD measurements. Besides, AGD measurements presented adequate accuracy for the diagnosis of LOH. Conclusions: This work adds to the scientific evidence that AGD—a biomarker of fetal exposure—could provide a non-invasive measure to address LOH, providing a potential useful clinical tool.

Investigating Skeletal Muscle Pump Function Using Thigh EMG, Thigh NIRS, And Stroke Volume Data In The FRAILMatics Physiological Cohort

Abstract Background The pioneering female physiologist Frances Hellebrandt first highlighted the significance of the skeletal muscle pump in circulation in the 1930s. However, the mechanisms underlying the muscle pump's function remain elusive, particularly in older individuals. It is thought that during muscle contraction, increased intramuscular pressure facilitates the expulsion of blood from the muscle's veins, aiding venous return. This contraction-induced pressure gradient assists in pushing blood towards the heart, increasing preload, and subsequently stroke volume (SV). In this study we investigated muscle pump activity using continuous measurements of thigh muscle activity, thigh total haemoglobin concentration (Hb), and cardiac SV. Methods 22 individuals (aged 70.8±5.3 years, 77.3% female) recruited from a Falls and Syncope Unit (St James’s Hospital, Dublin) underwent non-invasive measurements of Hb (NIRS PortaLite, Artinis Medical Systems, The Netherlands), electromyography (EMG) (Shimmer3, Research Ltd, Ireland), and SV (Finapres Nova, Finapres Medical Systems, The Netherlands) during a 10-second thigh squeeze test. Pre-processing involved data quality checks, alignment, and resampling. 60-second regions of interest were extracted, normalised, and processed using MATLAB (R2023a, TheMathWorks, Inc., Natick, MA, USA). Cross-correlation and Granger causality analyses were conducted to explore relationships between signals. Results Thigh Hb and EMG signals lagged 8.4 and 8.5 seconds behind SV, respectively. Granger Causality analysis revealed a significant causal relationship from both Hb and EMG to SV in 68% of participants at measured lags. Conclusion The observed ~8.5-second lag between thigh measurements and SV implies a plausible temporal relationship between muscle activation and venous return, further supported by significant causal relationships found in a substantial portion of participants using Granger causality analysis. These findings underscore the importance of continued research in this area, not only for advancing our understanding of physiological mechanisms but also for informing potential clinical applications aimed at optimising cardiovascular health and function.

Technology of the fish abundance accounting in fish farming cages using hydroacoustic and software tools

The purpose of the work: improvement of methods of fish number accounting in growing cages and reservoirs of fish farms using hydroacoustic tools and information technologies.Methods used: solving the problem of non-contact (non-invasive) measurement of the number of fish in cages using the hydroacoustic echo integration method. Investigation of the reflective properties of fish using a calibrated scientific echo sounder with a split beam. Carrying out measurements with different numbers of fish in cage. Identification and analysis of factors affecting the accuracy of the echo integration estimation of the number of fishes in cage.Novelty: the elements of novelty are the use of a scientific echo sounder with vertically oriented antenna and split beam to estimate the number of fishes in cages, the algorithm for calculating the number of fishes in cages by the echo integration method, the results of the study of reflective properties of Amur carp and identified optimal measurement conditions that allow hydroacoustic estimates of number with maximum accuracy.Results: the dependences of target strength on the linear size of Amur carp are obtained. An algorithmic scheme for calculating the number of fishes in cages by the hydroacoustic echo integration method has been developed. Experiments were carried out with different numbers of fish in the cage. It is established that the main factors affecting the accuracy of the population estimate are the number of individuals in the cage and the daily distribution of fish. Measurements at night and at concentrations above the threshold (50 pcs./m2) can significantly bring the estimated and true numbers of fish in the cage closer and reduce the variability of density estimates.Practical significance: solving the problem of remote measurement of the fish number in growing cages will allow farmers to optimize feed needs, which, in turn, will ensure rapid growth of fish without overfilling it and not polluting the reservoir.

Revealing in vivo broiler chicken growth state: Integrating CT imaging and deep learning for non-invasive reproductive phenotypic measurement

The measurement of body dimensions in broiler chickens has long been of great interest to the poultry industry, especially regarding reproductive phenotypes closely linked to breeding traits and the growth status of roosters. Existing measurement methods suffer from subjectivity, destructiveness, and various limitations. Therefore, we propose a novel method for the in vivo measurement of broiler chicken reproductive phenotype based on a three-dimensional medical imaging segmentation network. Leveraging our proposed FDTR medical imaging segmentation algorithm, this method achieves robust segmentation performance on a broiler chicken dataset. However, due to the morphological diversity and extreme class imbalance of broiler chicken reproductive phenotypes, we introduce a meta-learning paradigm and design a specialized decoder path. Ultimately, we establish relationships between the predicted results obtained from the segmentation network and the reproductive phenotypes to achieve phenotypic measurement. To evaluate this method, we collected and constructed the YF2023 broiler chicken reproductive phenotype dataset. Extensive cross-validation experiments demonstrate that the proposed method effectively measures the reproductive phenotypes of live roosters using computed tomography (CT) medical imaging. The proposed segmentation model achieves a mean fold dice similarity coefficient (DSC) of 0.6353, a mean fold Hausdorff distance (HD) of 11.84 mm, and a mean fold average volume distance (AVD) of 1.72 mm3. In addition, we evaluated our model’s generalization performance on unseen data, where the model achieved a DSC of 0.6825, an HD of 7.58 mm, and an AVD of 1.40 mm3. The predicted results exhibit a mean correlation coefficient of 66.18% with the weights of reproductive phenotype. This validates the enormous potential of the method in broiler chicken breeding and provides new insights and solutions for the accurate segmentation of broiler chicken reproductive phenotype. The code is available at https://github.com/Github-XKou/MetaFDTR.

Intraoperative hypotension in children-Measurement and treatment

Intraoperative hypotension is acommon perioperative complication in pediatric anesthesia. Oscillometric blood pressure measurement is therefore an essential part of standard perioperative monitoring in pediatric anesthesia. The optimum measurement site is the upper arm. Attention must be paid to the correct cuff size. Blood pressure should be measured before induction. In children undergoing major surgery or in critically ill children, invasive blood pressure measurement is still the gold standard. Continuous noninvasive measurement methods could be an alternative in the future.Threshold values to define hypotension remain unknown, even in awake children. There are also little data on hypotension thresholds in the perioperative setting. The most reliable measurement parameter for estimating hypotension is the mean arterial pressure. The threshold values for intraoperative hypotension are 40 mm Hg in newborns, 45 mm Hg in infants, 50 mm Hg in young children and 65 mm Hg in adolescents. Treatment should be initiated at adeviation of 10% and intensified at adeviation of 20%.Bolus administration of isotonic balanced crystalloid solutions, vasopressors and/or catecholamines are used as treatment options. Consistent and rapid intervention in the event of hypotension appears to be crucial. So far there is no evidence as to whether this leads to an improvement in outcome parameters.

Impact of age and sex on heart rate variability and cardiometabolic function in healthy adults

Heart rate variability (HRV) is a non-invasive measure of cardiac autonomic function. A clearer understanding as to whether resting autonomic function represented by HRV could be associated with changes in peak exercise cardiac function remains unanswered. This study evaluated the effect of age and sex on HRV, cardiometabolic function, and determined the correlation between HRV and cardiac function in healthy individuals. Sixty-eight participants (age range: 19–78 years old, females, n = 28) were recruited. Participants were stratified according to age (younger (<40 years old, n = 43, females, n = 17) and older age groups (>55 years old, n = 25, females, n = 11). Firstly, HRV was measured using non-invasive impedance cardiography method (TaskForce, CNSystems, Graz, Austria) and recorded at rest (supine position) for 30 min. HRV measures included: low frequency (LF) power, high frequency (HF) power (both normalised (nu) and absolute units (ms2)) and LF/HF ratio. Participants then completed a progressive cardiorespiratory exercise test using a semi-recumbent cycle ergometer (Corival, Lode, Groningen, Netherlands) with simultaneous gas exchange measurements (Metalyzer 3B, Cortex, Leipzig, Germany). Cardiac function was represented by peak exercise cardiac power output index (CPO). After controlling for body mass index and physical activity, males had significantly higher mean vales of RR interval than females (males = 1043 ± 165; females = 952 ± 128 ms, p = 0.02). There was no significant main effect of age, sex or their interaction on any of the other HRV measures. In younger and older females, resting RR interval had a significant relationship with peak exercise CPO (young females: r = 0.54, p < 0.05; old females: r = 0.81, p < 0.01). There was also a significant relationship between resting HF power and peak exercise CPO in younger females (r = 0.70, p < 0.01). HRV was not influenced by age but RR interval was associated with peak exercise CPO in females regardless of age, whilst HF power was significantly associated with CPO in younger females only.

Development of a unified framework of low-rank approximation and deep neural networks for predicting the spatial variability of SSC in `Spania' watermelons using vis/NIR hyperspectral imaging

Soluble Solids Content (SSC) is an important quality attribute that represents the internal quality of fruits. Visible and near-infrared (Vis/NIR) combined with chemometric algorithms are now popular methods for non-invasive measurement and visualization of SSC. However, in fruits with a thick rind and a large flesh volume, such as watermelon, SSC is not evenly distributed across the fruit. The variability in SSC across the fruit flesh may have an adverse effect on the accuracy of quality analysis algorithms. Thus, this paper presents an accurate and efficient approach for predicting the spatial variation of SSC in watermelons using a combined framework of low-rank approximation and deep neural networks. Watermelon ‘Spania’ was selected for this study, and hyperspectral images of each watermelon were taken from various views, including the top, bottom, and two lateral views. The low-rank property is employed as a constraint in this approach to eliminate the unwanted variations in the spectral data. The low-rank component of the spectral data, free of unwanted variations, is then fed into a fully connected neural network (FNN) for the prediction of watermelon SSC values. The proposed approach obtained optimal performance in calibration and prediction with RC2=0.982, RMSEP = 0.132, and RP2=0.945, RMSEP = 0.195 respectively. Further, the prediction outcomes of the proposed method were compared with state-of-the-art such as Partial Least Square Regression (PLSR), Support Vector Regression (SVR), Multiple Linear Regression (MLR), Decision Tree (DT), and Random Forest (RF). The overall results showed that combining HSI data with a low-rank and deep neural network framework is an efficient method for accurately predicting SSC in watermelons as well as correctly predicting spatial variability of SSC in individual fruits.

Assessing Mechanochemical Properties of Acrylonitrile Butadiene Styrene (ABS) Items in Cultural Heritage Through a Multimodal Spectroscopic Approach.

A multimodal spectroscopic approach is proposed to correlate the mechanical and chemical properties of plastic materials in art and design objects, at both surface and subsurface levels, to obtain information about their conservation state and to monitor their degradation. The approach was used to investigate the photo-oxidation of acrylonitrile butadiene styrene (ABS), a plastic commonly found in many artistic and design applications, using ABS-based LEGO bricks as model samples. The modifications of the chemical and viscoelastic properties of ABS during photoaging were monitored by correlative Brillouin and Raman microspectroscopy (BRaMS), combined with portable and noninvasive broad-range external reflection infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) relaxometry, directly applicable in museums. BRaMS enabled combined measurements of Brillouin light scattering and Raman spectroscopy in a microspectroscopic setup, providing for the coincident probe of the chemical and mechanical changes of ABS at the sample surface. NMR relaxometry allowed for noninvasive measurements of relaxation times and depth profiles which are directly related to the molecular mobility of the material. Complementary chemical information was acquired by external reflection IR spectroscopy. The simultaneous probe of the chemical and mechanical properties by this multimodal spectroscopic approach enabled us to define a decay model of ABS in terms of compositional changes and variation of stiffness and rigidity occurring with photodegradation. The knowledge acquired on LEGO samples has been used to rate the conservation state of ABS design objects noninvasively investigated by external reflection Fourier transform IR spectroscopy and NMR relaxometry offered by the MObile LABoratory (MOLAB) platform of the European Research Infrastructure of Heritage Science.

Magnetic resonance reveals early lipid deposition in murine prediabetes as predictive marker for cardiovascular injury

People with diabetes have an increased cardiovascular risk and a poorer outcome after myocardial infarction (MI). However, the exact underlying mechanisms are still unclear, as is the question of which non-invasive measures could be used to predict the altered risk for the patient at early stages of the disease and adapt personalized treatment. Here, we used a holistic magnetic resonance approach to monitor longitudinally not only the main target heart, but also liver, peripheral/skeletal muscle, bone marrow, and hematopoiesis during disease development and subsequent MI. In prediabetic mice, we found a strong accumulation of lipids in all organs which preceded even a significant whole-body weight gain. Intramyocellular lipids (IMCLs) were most sensitive to reveal in vivo very early alterations in tissue properties during the prediabetic state. Subsequent induction of MI led to a persistent impairment of contractile function in septal/posterior segments of prediabetic hearts which correlated with their lipid load prior MI. At the same time, prediabetic cardiomyocytes exhibited sarcomere function at its limit resulting in overload and lower compensatory contractility of the healthy myocardium after MI. In summary, we identified IMCLs as very early marker in murine prediabetes and together with the cardiac lipid load as predictive for the functional outcome after MI.

Photoacoustic thermal-strain measurement towards noninvasive and accurate temperature mapping in photothermal therapy

Photothermal therapy is a promising tumor treatment approach that selectively eliminates cancer cells while assuring the survival of normal cells. It transforms light energy into thermal energy, making it gentle, targeted, and devoid of radiation. However, the efficacy of treatment is hampered by the absence of accurate and noninvasive temperature measurement method in the therapy. Therefore, there is a pressing demand for a noninvasive temperature measurement method that is real-time and accurate. This article presents one such attempt based on thermal strain photoacoustic (PA) temperature measurement. The method was first modelled, and a circular array-based photoacoustic photothermal system was developed. Experiments with Indian ink as tumor simulants suggest that the temperature monitoring in this work achieves a precision of down to 0.3 °C. Furthermore, it is possible to accomplish real-time temperature imaging, providing accurate two-dimensional temperature mapping for photothermal therapy. Experiments were also conducted on human fingers and nude mice, validating promising potentials of the proposed method for practical implementations.

Precision engineering of surface defects of cerium oxide nanostructured fine particles for the multiplexed detection of electrolytes and glucose inside tissue models

The development of biosensors for the detection of glucose and electrolytes has become a crucial field of research nowadays due to the increasing incidence of long-term conditions. Specifically, the use of cerium oxide as a selective material for the detection of glucose is raising interest as an alternative to enzymatic sensors due to their stability and low-cost. This work demonstrates for the first time a significant improvement in the selectivity of glucose sensors based on cerium oxide nanostructured fine particles through doping with nickel ions and using pulse voltammetry for the sensing. By using nickel-doped cerium oxide fine particles, the sensitivity of the devices improved by 10-fold, and the selectivity when testing the devices against lactate increased by 68.5 % as compared to pure cerium oxide fine particles, with a limit of detection in the micromolar level. Crystallographic and compositional properties that led to such increase in sensitivity were determined, as a result of a presence of oxygen defects and amorphous domains at the surface of fine particles. This device could be adapted for the simultaneous measurement of glucose and sodium ions. The pulse voltametric approach enhanced the sensitivity of the sensors towards sodium ions, which reached a super-Nernstian sensitivity of 111 mV Log[Na+]-1, with a response time of 2 mins, and has been used for the testing of the electrodes in a practical environment using a skin-inspired material. This technology will pave the way for the development of miniaturised non-invasive wearable sensors real-time measurement of glucose and electrolytes in patients.

Heat and mass transfer visualisation of an exothermic acid-base microfluidic reactor using infrared thermospectroscopy

ABSTRACT Here, a microfluidic reactor that is transparent in the mid-wave infrared spectrum with an effective path length of 38 µm is developed for characterisation via operando Fourier-transform Infrared (FTIR) thermospectroscopy. This imaging technique couples an infrared (IR) camera with an FTIR spectrometer to quantify heat and mass transfer in the exothermic acid-base reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH). The absorbance fields of the reaction are used to simultaneously derive the molar concentration fields of the reactants (HCl and NaOH) and products (sodium chloride [NaCl]) at the microscale through a linear inverse method. The heat generated at the reaction interface is visualised through a thermal field captured from the measured proper emission. Concentration and thermal fields are then compared to an advection-diffusion model for validation. The results proposed in this work present a refined contactless calorimetry process for characterising the heat and mass transport in an acid-base reaction. Further refinement of this work will enable accurate and non-invasive measurements for the enthalpy of reaction in chemical reactions.

Non-invasive mass flow and local heat transfer coefficient measurements in pulsating heat pipes

A single loop Pulsating Heating Pipe (PHP) experimental setup was developed for non-invasive measurement of the local heat transfer coefficient and the mass flow along the PHP evaporator. These measurements are valuable to validate modeling tools used in the design of PHP. A two-step differential heat input method was used for measurement of mass flow and the results were compared with the optical and theoretical results. The conditions tested in the PHP were 50, 60 and 70% filling ratio, R134a as working fluid, internal diameter of 2 mm, saturation temperature of between 30 to 40 °C, inclination angles from 30 to 90° (vertical bottom heat mode) and heat loads on the evaporator from 10 up to 68 W. The results indicate a high performance in heat transfer of the PHP, with minimum internal thermal resistance values close to 0.008 K/W as well as local heat transfer coefficients greater than 10 kW/m2K for observed values of mass velocities between 60 and 140 kg/m2s. The results were compared with correlations from the literature and these were able to predict the results with a 20% average error margin, suggesting many similarities with convective boiling mechanisms.