3D-printed Holder Research Articles

A simple color absorption analysis of colorimetric loop-mediated isothermal amplification for detection of Raillietina spp. in clinical samples using a 3D-printed tube holder coupled with a smartphone camera and notebook screen.

Asimple method has been developedfor semi-quantitative analysis of the colorimetric output of loop-mediated isothermal amplification (LAMP) using a 3D-printed tube holder with a smartphone and notebook for the detection of Raillietina, which is the cause of Raillietiniasis affecting free-range chicken farming. In this method, a light is directedfrom a notebook screen to the LAMP products in the tube holder and the color absorption of the LAMP products is measured by using the appropriate smartphone application. It was found that the malachite green dye-coupled LAMP (MaG-LAMP) assay showed the highest sensitivity and specificity for detecting Raillietina without any cross-reaction with other related parasites and hosts. The limit of detection was 10fg/μL of DNA. A total of 60 fecal samples were infectively confirmed by microscopic examination and the results of microscopy compared with those of MaG-LAMP and triplex PCR assays. Microscopy and MaG-LAMP based on the color absorption demonstrated high agreement in Raillietina detection with kappa = 1. Rapid, simple, cost-effective, and easy interpretation of colorimetric LAMP assays and their high sensitivity make them superior to PCR and morphological investigation, demonstrating the feasibility of this assay in point-of-care screening to support farm management and solve chicken health problems. Our study presentsis an alternative diagnostic method using semi-quantitative analysis of colorimetric LAMP based on the differing solution color absorptions between positive and negative reactions for infectious disease diagnosis.

Pollen-based natural nanostructures to realize nanoplasmonic biochips for single-molecule detection

In this work, a paradigm change in the development of the plasmonic-based bio/chemical sensing approaches is presented. The proposed idea is to use natural nanostructures instead of those fabricated by electron-beam lithography (EBL) tools. This sensing approach produces several advantages, such as high performances without an optimization step and a simple, low-cost, and eco-friendly production process with respect to other methods, which are still time-consuming with low scalability. In particular, pollen's nanostructures covered by gold nanofilms are used to realize gold nanogratings (GNG), similar to those made via EBL, to excite hybrid plasmonic phenomena. Bulk and binding sensitivities are evaluated and compared to nanoplasmonic sensors, particularly those achieved via an EBL-based chip. As proof of principle, an estrogen receptor (ERα) is immobilized on the plasmonic nanostructured surfaces of both EBL-based and pollen-based chips and interrogated by the same custom 3D-printed holder through a transmission-based experimental setup, exploiting polymer optical fibers (POFs). The experimental results demonstrate that the proposed pollen-based nanoplasmonic biosensor shows performance very similar to an EBL-based nanoplasmonic biosensor, indicating the equivalence between the two nanoplasmonic biosensors. The biosensor exhibited a detection limit better than 1 aM for the estradiol, demonstrating the capabilities of the proposed sensing approach towards single-molecule detection.

Determining pair distribution functions of thin films using laboratory-based X-ray sources.

This article demonstrates the feasibility of obtaining accurate pair distribution functions of thin amorphous films down to 80 nm, using modern laboratory-based X-ray sources. The pair distribution functions are obtained using a single diffraction scan without the requirement of additional scans of the substrate or of the air. By using a crystalline substrate combined with an oblique scattering geometry, most of the Bragg scattering of the substrate is avoided, rendering the substrate Compton scattering the primary contribution. By utilizing a discriminating energy filter, available in the latest generation of modern detectors, it is demonstrated that the Compton intensity can further be reduced to negligible levels at higher wavevector values. Scattering from the sample holder and the air is minimized by the systematic selection of pixels in the detector image based on the projected detection footprint of the sample and the use of a 3D-printed sample holder. Finally, X-ray optical effects in the absorption factors and the ratios between the Compton intensity of the substrate and film are taken into account by using a theoretical tool that simulates the electric field inside the film and the substrate, which aids in planning both the sample design and the measurement protocol.

Streamlined integrated protein isoelectric focusing using microfluidic paper-based device

An innovative integrated paper-based microdevice was developed for protein separation by isoelectric focusing (IEF), allowing for robust design thanks to a 3D-printed holder integrating separation channel, reservoirs, and electrodes. To reach robustness and precision, the optimization focused on the holder geometry, the paper nature, the reservoir design, the IEF medium, and various focusing parameters. A well-established and stable pH gradient was obtained on a glass-fiber paper substrate with simple sponge reservoirs, and the integration of the electrodes in the holder led to a straightforward system. The separation medium composed of water/glycerol (85/15, v/v) allowed for reducing medium evaporation while being an efficient medium for most hydrophobic and hydrophilic proteins, compatible with mass spectrometry detection for further proteomics developments. To our knowledge, this is the first report of the use of glycerol solutions as a separation medium in a paper-based microdevice. Analytical performances regarding pH gradient generation, pI determination, separation efficiency, and resolution were estimated while varying the IEF experimental parameters. The overall process led to an efficient separation within 25 min. Then, this methodology was applied to a sample composed of saliva doped with proteins. A minimal matrix effect was evidenced, underscoring the practical viability of our platform. This low-cost, versatile and robust paper-based IEF microdevice opens the way to various applications, ranging from sample pre-treatment to integration in an overall proteomic-on-a-chip device.

3D-integrated membrane protected micro-solid-phase extraction of sulfonamides in food samples: An innovative approach

A sensitive, eco-friendly and cost-effective 3D-integrated membrane-protected micro solid-phase extraction (3D-MP-µ-SPE) method was developed for the determination of sulfonamides (SAs) in water, milk and fish samples prior to high-performance liquid chromatography with diode array detection (HPLC-DAD). Innovatively, a 3D-printed filter holder was designed and printed by a stereolithography (SLA) printer to securely hold the µ-SPE device for extracting four SAs-: sulfadiazine (SDZ), sulfachloropyridazine (SCP), sulfamethoxazole (SMX) and sulfadimethoxine (SDM). The µ-SPE device was prepared using a nylon filter mesh, and 60 mg of Strata X was placed inside and heat sealed. Optimization parameters of the 3D-MP-µ-SPE method were studied including − type of preconditioning solvent, dosage amount, effect of drying, sample volume, number of extraction and desorption flows, type and volume of desorption solvent, and pH. Under the optimized conditions, good linearity was observed between 1 and 500 µg L−1 with an R2 of 0.9931 to 0.9994 for all the SAs. The limit of detection and quantification ranged between 0.16–0.54 µg L−1 and 0.49–1.65 µg L−1 respectively. The method demonstrated good extraction recovery (84.2 % to 114.5 %) for real sample analysis, with a relative standard deviation of less than 5.9 %. Moreover, the Analytical GREEnness (AGREE) score of 0.66 indicates the environmental friendliness of the proposed method. In conclusion, this 3D-MP-µ-SPE method offers a sustainable and efficient solution for SAs determination, with robust performance and minimal environmental impact.

Photoluminescence Measurement of Triplet Sensitizer-Emitter Solution Using a Customized 3D-Printed Sample Holder

This study explores the photoluminescence (PL) measurement of triplet sensitizer-emitter (TSE) solutions using a custom 3D-printed sample holder, within the context of triplet-triplet annihilation based molecular photon upconversion (TTA-UC) systems targeting the Vis-to-UV spectral region. TTA-UC converts low-energy visible photons to higher-energy ultraviolet (UV) photons, holding promise for solar energy harvesting and photonics applications. Two TSE couples, 4CzIPN/TP and 4CzIPN/QP, were investigated, and their upconverted fluorescence spectra showed peaks at 344 nm and 354 nm / 370 nm, respectively, confirming efficient upconversion capabilities. The 3D-printed sample holder facilitated reproducible PL measurements, enabling the calculation of quantum yields (ΦUC). The 4CzIPN/TP and 4CzIPN/QP couples exhibited low quantum yields (0.028% and 0.043%, respectively), suggesting the need for improved deoxygenation methods to enhance the triplet-triplet annihilation process and overall quantum efficiency. Despite modest yields, successful UV upconverted fluorescence observation underscores the feasibility of the Vis-to-UV TTA-UC system. This study provides insights into TTA-UC optimization and demonstrates the utility of the 3D-printed sample holder for affordable and precise PL measurements, paving the way for future advancements in photonics and solar energy applications.

3D-printed weight holders design and testing in mouse models of spinal cord injury

This paper details the comprehensive design and prototyping of a 3D-printed wearable device tailored for mouse models which addresses the need for non-invasive applications in spinal cord studies and therapeutic treatments. Our work was prompted by the increasing demand for wearable devices in preclinical research on freely behaving rodent models of spinal cord injury. We present an innovative solution that employs compliant 3D-printed structures for stable device placement on the backs of both healthy and spinal cord-injured mice. In our trial, the device was represented by two magnets that applied passive magnetic stimulation to the injury site. This device was designed to be combined with the use of magnetic nanoparticles to render neurons or neural cells sensitive to an exogenous magnetic field, resulting in the stimulation of axon growth in response to a pulling force. We show different design iterations, emphasizing the challenges faced and the solutions proposed during the design process. The iterative design process involved multiple phases, from the magnet holder (MH) to the wearable device configurations. The latter included different approaches: a “Fitbit”, “Belt”, “Bib”, and ultimately a “Cape”. Each design iteration was accompanied by a testing protocol involving healthy and injured mice, with qualitative assessments focusing on animal wellbeing. Follow-up lasted for at least 21 consecutive days, thus allowing animal welfare to be accurately monitored. The final Cape design was our best compromise between the need for a thin structure that would not hinder movement and the resistance required to maintain the structure at the correct position while withstanding biting and mechanical stress. The detailed account of the iterative design process and testing procedures provides valuable insights for researchers and practitioners engaged in the development of wearable devices for mice, particularly in the context of spinal cord studies and therapeutic treatments. Finally, in addition to describing the design of a 3D-printed wearable holder, we also outline some general guidelines for the design of wearable devices.

Novel 3D printed universal conical holder for eye plaque quality assurance

For the custom-built construction of eye plaques, the iodine (I-125) seeds of different source strengths are recycled in our eye plaque program. To return I-125 seeds to the correct lot, we developed a novel 3D-printed conical plaque QA holder for relative assay for eye plaques. A universal 3D-printed conical plaque holder was designed to accommodate six plaque sizes and fit reproducibly in a well-type dose calibrator. A reproducibility test was used to compare the plaque placement consistency in the holder versus without the holder. Plaque assays were performed for assembled plaques both before implant and after explant. The explant reading was compared with the implant reading adjusted for decay, and the relative error was calculated. The plaque response fraction (PRF) is defined as the fraction of well chamber implant reading over the total seed strength for a plaque. The PRF was aggregated for each individual plaque to confirm the seed lot before implant. The reproducibility test showed the chamber reading's relative standard deviation of 0.40% with the QA holder compared to 0.68% without it. The batch relative assay was performed for 251 plaques. The absolute value of measurement deviation between explant and decay-corrected implant readings is 0.89%±0.86% (mean±standard deviation). The PRFs for individual plaques range from 36.49% to 49.87%, with a maximum standard deviation of 2%. This novel 3D-printed QA holder provides reproducible setup for assaying assembled eye plaques in a well chamber. Batch relative assay can validate the seed batch used and plaque integrity during the implant without assaying individual seeds, saving valuable physicist time and radiation exposure from seed handling.

Towards ultra-low-cost smartphone microscopy.

The outbreak of COVID-19 exposed the inadequacy of our technical tools for home health surveillance, and recent studies have shown the potential of smartphones as a universal optical microscopic imaging platform for such applications. However, most of them use laboratory-grade optomechanical components and transmitted illuminations to ensure focus tuning capability and imaging quality, which keeps the cost of the equipment high. Here, we propose an ultra-low-cost solution for smartphone microscopy. To realize focus tunability, we designed a seesaw-like structure capable of converting large displacements on one side into small displacements on the other (reduced to ∼9.1%), which leverages the intrinsic flexibility of 3D printing materials. We achieved a focus-tuning accuracy of ∼5 𝜇m, which is 40 times higher than the machining accuracy of the 3D-printed lens holder itself. For microscopic imaging, we used an off-the-shelf smartphone camera lens as the objective and the built-in flashlight as the illumination. To compensate for the resulting image quality degradation, we developed a learning-based image enhancement method. We used the CycleGAN architecture to establish the mapping from smartphone microscope images to benchtop microscope images without pairing. We verified the imaging performance on different biomedical samples. Except for the smartphone, we kept the full costs of the device under 4 USD. We think these efforts to lower the costs of smartphone microscopes will benefit their applications in various scenarios, such as point-of-care testing, on-site diagnosis, and home health surveillance. RESEARCH HIGHLIGHTS: We propose a solution for ultra-low-cost smartphone microscopy. Utilizing the flexibility of 3D-printed material, we can achieve focusing accuracy of ∼5 𝜇m. Such a low-cost device will benefit point-of-care diagnosis and home health surveillance.

(117) Interrater Agreement and Feasibility of Three-Dimensional Photography for Curvature Assessment in Peyronie's Disease

Abstract Introduction Curvature assessment is an iterative aspect of the evaluation of Peyronie’s Disease (PD); its accuracy is subject to patient erection quality and clinician technique. Prior studies have shown promising results when using 3D modeling software in curvature assessment, yet none have applied the technology to human subjects with complex PD in an authentic clinical scenario. Objective To evaluate the feasibility of using 3D modeling to assess penile deformity in PD patients. Methods MirrorMe3D is a HIPPA-compliant iOS mobile and web-based platform designed for 3D anatomical modeling. 2 trained urology fellows (coders 1 and 2) were trained to create models using the app by acquiring ≥ 12 images of the target obtained in a multiplanar, 360-degree fashion. Participants verbally consented to deidentified penile photography during their clinic visit for penile curvature assessment with Doppler ultrasound (CADUS). Photographs were obtained prior to performing DUS with the patient in the supine position and using a commercially available clip-on ring light and custom 3D-printed holder device placed over the penis base for stabilization. 3D models were generated upon completion of the visit and screened for quality. Curvature assessment on the 3D images included curvature direction, location, degrees, and other defects identified via visual inspection of the digital model. Results 7 unique, quality 3D images were generated using 15-20 photos per participant (Figure 1). The time required to obtain images was 1-2 minutes. Once the 3D image was developed, the curvature assessment took about 5 minutes. Quantitative results are summarized in Table 1. We observed a high rate of agreement in terms of primary direction of curvature and an acceptable variance rate when evaluating degrees of curvature within a margin of 10°; of note, coders were in agreement with each other to within a 10° margin 100% of the time (7/7 patients). We also observed a high agreement rate when evaluating the presence of absence of tapering but low agreement when assessing for the presence of indentation and hourglass deformity. Regarding the penis stabilizer, our experience suggests that it may alter the base of the penis anatomy, but it improves capture of the organ with diminished interference from surrounding anatomy (scrotum, abdomen). Factors influencing the quality of the image were exam room set-up, patient anxiety about losing an erection, lighting, and body hair. Conclusions 3D image-based PD assessment can be implemented with minimal impact to visit efficiency. The 3D technique does not appear to reproduce complex PD measurements obtained by CADUS; however, future studies will evaluate the utility of employing this technology to a larger cohort and also to monitor treatment effect in complex PD patients. Disclosure No.

Whole transcriptome analysis highlights nutrient limitation of nitrogen cycle bacteria in simulated microgravity

Regenerative life support systems (RLSS) will play a vital role in achieving self-sufficiency during long-distance space travel. Urine conversion into a liquid nitrate-based fertilizer is a key process in most RLSS. This study describes the effects of simulated microgravity (SMG) on Comamonas testosteroni, Nitrosomonas europaea, Nitrobacter winogradskyi and a tripartite culture of the three, in the context of nitrogen recovery for the Micro-Ecological Life Support System Alternative (MELiSSA). Rotary cell culture systems (RCCS) and random positioning machines (RPM) were used as SMG analogues. The transcriptional responses of the cultures were elucidated. For CO2-producing C. testosteroni and the tripartite culture, a PermaLifeTM PL-70 cell culture bag mounted on an in-house 3D-printed holder was applied to eliminate air bubble formation during SMG cultivation. Gene expression changes indicated that the fluid dynamics in SMG caused nutrient and O2 limitation. Genes involved in urea hydrolysis and nitrification were minimally affected, while denitrification-related gene expression was increased. The findings highlight potential challenges for nitrogen recovery in space.

SlipO2Chip - single-cell respiration under tuneable environments.

In disciplines like toxicology and pharmacology, oxygen (O2) respiration is a universal metric for evaluating the effects of chemicals across various model systems, including mammalian and microalgal cells. However, for these cells the common practice is to segregate populations into control and exposure groups, which assumes direct equivalence in their responses and does not take into account heterogeneity among individual cells. This lack of resolution impedes our ability to precisely investigate differences among experimental groups with small or limited sample sizes. To overcome this barrier, we introduce SlipO2Chip, an innovative glass microfluidic platform for precisely quantifying single-cell O2 respiration in the coordinated absence and presence of chemical solutes. SlipO2Chip comprises a wet-etched fused silica channel plate on the top and a dry-etched borosilicate microwell plate at the bottom. The microwells are coated with Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP), an O2 sensing optode material and an O2-independent reference dye. A custom 3D-printed holder facilitates the controlled horizontal movement ('slipping') of the channel plate over the microwell plate, thereby establishing or disrupting the fluid path over microwells. Collectively, these design elements enable the immobilization of single-cells in microwells, their exposure to controlled fluid flows, the coordinated opening and closing of microwells and repeated measurements of single-cell O2 respiration. Uniquely, by sequentially executing opening and closing it becomes possible to measure single-cell respiration prior to and after exposure to chemical solutes. In a proof-of-concept application, we utilized SlipO2Chip to measure the impact of increasing exposures of the marine bacterial signal 2-heptyl-4-quinolone (HHQ) on the dark respiration of the diatom Ditylum brightwellii at single-cell resolution. Results revealed a concentration-dependent decrease in per-cell O2 dark respiration, with a maximum reduction of 40.2% observed at HHQ concentrations exceeding 35.5 μM, and a half-maximal effective concentration (EC50) of 5.8 μM, consistent with that obtained via conventional bulk respiration methods. The ability of SlipO2Chip to sequentially assess the effects of chemical substances on single-cell O2 metabolism is advantageous for research where sample volumes are limited, such as clinical biopsies, studies involving rare microbial isolates, and toxicological studies aiming to address exposure effects while accounting for cell-to-cell variability.

Non-contact Laser Interferometer Method to Characterize Tablet Punches: New Methodology to Assess Surface Roughness.

Sticking to tablet punches is a major issue during drug product manufacturing. Research has shown that sticking involves the interrelationship of powder properties, compression force, length of manufacturing runs and punch quality. Here, we present a novel non-destructive methodology to study the surface metrology of punches to monitor them over their lifetime.This investigation used a non-contact laser interferometer to characterise roughness of commercial standard S7 steel punches coated with chrome that were originally used for commercial scale production that developed a sticking issue. During the development, this phenomenon had not been observed and was not considered a scale-up risk. The profilometer was used to examine the complete surface of these punches to investigate whether they met the acceptability criteria based on BS_ISO_18804 tooling standard. To improve data analysis during changeover, a 3D-printed holder was designed to enable analysis with minimal set-up requirements.Upon investigation, the punches were found to be of an unacceptable roughness and, particularly rough areas of the punch surface profiled, correlated well with areas of visually pronounced sticking.This non-destructive method can be used to produce a more detailed characterisation of punch roughness toensure surfaces are of an acceptable quality after treatment with coatings.

Design and construction of the MUSE permanent magnet stellarator

This paper documents the design and construction of MUSE, the world's first permanent magnet (PM) stellarator and the first quasi-axisymmetric experiment. The purpose of MUSE is to develop and assess a new way of building optimised stellarators that uses simple planar coils PMs. Our PM optimisation algorithm consists of initialising a geometry to pack dipoles densely, running the FAMUS code to minimise surface field error subject to PM constraints and applying discrete jumps to reach a physically realisable solution. FAMUS treats the PM system as a set of ideal point dipoles. From there we construct finite-volume magnet towers to be housed in 3D-printed PM holders. We describe the design of the PM holders, which were validated by laser metrology. We analyse the effects of finite permeability, sensitivity to perturbations and magnetostatic forces. An exact analytic formula for the magnetic field from a finite-volume PM tower is presented to compute PM–PM forces and stress on the PM holder. Stellarator construction is complete and experiments are underway.

3D-printed dual holder system for simultaneous rat PET scanning: design and influence on quantification

BackgroundThe low throughout of small animal positron emission tomography (PET) images acquisitions represents a substantial limitation. The aims of this study were (i) to design a low-cost support for simultaneous dynamic PET scanning of two lying rats and (ii) to study its impact on brain image quantification.ResultsAccuracy of concentration measurement was 5.5% for one phantom in the field of view, and 5.7% for two phantoms measured simultaneously. Ratio concentration between phantoms showed an error of 6.7% ± 5.1% for Solo upper position, 6.7% ± 3.7% for Solo lower position, 5.9% ± 4.3% for Duo upper position, and 7.4% ± 6% for Duo lower position 6.7% for separated measures, and 6.6% for simultaneous measures.In vivo distribution profiles showed no difference between solo and duo uptakes. Region of Interest quantification in the whole brain showed 4.4% variability solo and 3.5% duo. The quantified test–retest bias was 8% in solo and 5% in duo, and the Intraclass Correlation Coefficient was comparable in solo and duo (0.969 vs. 0.966).ConclusionsOur results showed that simultaneous scans of two rats in INVEON do not affect quantification. The dual support system will allow us to reduce protocol costs and duration.

3D-printed holder for drawing highly reproducible pencil-on-paper electrochemical devices.

Pencil drawing is one of the simplest and most cost-effective ways of fabricating miniaturized electrodes on a paper substrate. However, it is limited by the lack of reproducibility regarding the electrode drawing process. A 3D-printed pencil holder (3DPH) is proposed here for simple, reproducible, and low-cost hand-drawn fabrication of paper-based electrochemical devices. 3DPH was designed to keep pressure and angulation of the graphite mine constant on the paper substrate using a micromechanical pencil regardless of the user/operator. This approach significantly improved the reproducibility and cost of making reliable pencil-drawn electrodes. The results showed high reproducibility and accuracy of the 3DPH-assisted electrodes prepared by 4 different operators in terms of sheet resistance and electrochemical behavior. Cyclic voltammetric (CV) curves in the presence of [Fe(CN)6]3-/4- redox probe showed only 3.9% variation for the anodic peak currents of different electrodes prepared by different operators when compared with electrodes prepared without the 3D-printed support. SEM analyses revealed a more uniform graphite deposition/design of the electrodes prepared with 3DPH, which corroborates the results obtained by CV. As a proof of concept, 3DPH-assisted pencil-drawn graphite electrodes were employed for dopamine detection in synthetic saliva, showing a proportional increase in anodic peak current at 0.12 V vs. carbon pRE with increasing dopamine (DA) concentration, with a detection limit of 0.39μmol L-1. Moreover recoverywas in the range93-104% of DA (4-7% RSD) in synthetic saliva for three different concentrations, demonstrating the reliability of the approach. Finally, we believe this approach can make pencil-drawn technology more robust, accessible, reliable, and inexpensive for real on-site applications, especially in hard-to-reach locations or research centers with little investment.

Teaching with Arduino: Porphyrinoids’ fluorescence in olive oil

During the pandemic period, we were forced to reconsider teaching of practical labs, as students had mainly to work at home. It was the occasion to explore the use of cheap microcontroller kits for teaching chemistry and to work out some manipulations with household products. Back to normal life, it is important to valorize this equipment and work to design simple chemistry experiments which could be performed by students at home with Arduino kits adapted to chemistry, to illustrate various courses in addition to classical manipulations performed in the laboratory with specific equipment and products. We describe here the construction of a simple and cheap Arduino-based fluorimeter and its use to study relative porphyrinoids (mainly chlorophylls and pheophytins) contents in olive oils, and the effect of heating on the degradation of such substances. We used an Arduino Uno kit with a LED, a light-to-frequency converter associated with an excitation-blocking filter, and a 3D-printed sample holder.

A 3D-Printed Phantom Twin and Multi-Transducer Holder for Dynamic Anatomical Ultrasonography of the Lower Limb

We aim to improve the residuum health of individuals suffering from lower-limb loss through ‘digital twin’ computational simulations for the creation of optimized 3D-printed prosthetic attachments. Our objective is to utilize 4D tracking data of various tissue interfaces as a primary input into the digital twin. Dynamic anatomical ultrasonography (DAU) is a novel technique in which synchronized individual transducers are positioned at known locations utilizing a 3D-printed holder. Pulse-echo ultrasound data are recorded and subsequently analyzed, providing plots of tissue interface depths versus recording time. For the scientific validation of the DAU technique, a bespoke 3D-printed phantom twin has been created incorporating replica compartments of soft-tissue interfaces and bone tissue of a healthy thigh. To demonstrate its utility, a preliminary experiment was performed in which the phantom twin was positioned within the DAU device and the replica bone manually traversed randomly; subsequent DAU analysis provided a plot of interface depth versus recording time.

Digital microfluidic platform assembled into a home-made studio for sample preparation and colorimetric sensing of S-nitrosocysteine.

Digital microfluidics (DMF) is a versatile lab-on-a-chip platform that allows integration with several types of sensors and detection techniques, including colorimetric sensors. Here, we propose, for the first time, the integration of DMF chips into a mini studio containing a 3D-printed holder with previously fixed UV-LEDs to promote sample degradation on the chip surface before a complete analytical procedure involving reagent mixture, colorimetric reaction, and detection through a webcam integrated on the equipment. As a proof-of-concept, the feasibility of the integrated system was successfully through the indirect analysis of S-nitrosocysteine (CySNO) in biological samples. For this purpose, UV-LEDs were explored to perform the photolytic cleavage of CySNO, thus generating nitrite and subproducts directly on DMF chip. Nitrite was then colorimetrically detected based on a modified Griess reaction, in which reagents were prepared through a programable movement of droplets on DMF devices. The assembling and the experimental parameters were optimized, and the proposed integration exhibited a satisfactory correlation with the results acquired using a desktop scanner. Under the optimal experimental conditions, the obtained CySNO degradation to nitrite was 96%. Considering the analytical parameters, the proposed approach revealed linear behavior in the CySNO concentration range between 12.5 and 400μmolL-1 and a limit of detection equal to 2.8μmolL-1. Synthetic serum and human plasma samples were successfully analyzed, and the achieved results did not statistically differ from the data recorded by spectrophotometry at the confidence level of 95%, thus indicating the huge potential of the integration between DMF and mini studio to promote complete analysis of lowmolecular weight compounds.

Hands-free continuous transthoracic echocardiography and transcranial Doppler using a 3D-printed transducer holder connected to a hydraulic arm

Hands-free continuous transthoracic echocardiography and transcranial Doppler using a 3D-printed transducer holder connected to a hydraulic arm