New tree height allometries derived from terrestrial laser scanning reveal substantial discrepancies with forest inventory methods in tropical rainforests.

Tree allometric models, essential for monitoring and predicting terrestrial carbon stocks, are traditionally built on global databases with forest inventory measurements of stem diameter (D) and tree height (H). However, these databases often combine H measurements obtained through various measurement methods, each with distinct error patterns, affecting the resulting H:D allometries. In recent decades, terrestrial laser scanning (TLS) has emerged as a widely accepted method for accurate, non-destructive tree structural measurements. This study used TLS data to evaluate the prediction accuracy of forest inventory-based H:D allometries and to develop more accurate pantropical allometries. We considered 19 tropical rainforest plots across four continents. Eleven plots had forest inventory and RIEGL VZ-400(i) TLS-based D and H data, allowing accuracy assessment of local forest inventory-based H:D allometries. Additionally, TLS-based data from 1951 trees from all 19 plots were used to create new pantropical H:D allometries for tropical rainforests. Our findings reveal that in most plots, forest inventory-based H:D allometries underestimated H compared with TLS-based allometries. For 30-metre-tall trees, these underestimations varied from -1.6 m (-5.3%) to -7.5 m (-25.4%). In the Malaysian plot with trees reaching up to 77 m in height, the underestimation was as much as -31.7 m (-41.3%). We propose a TLS-based pantropical H:D allometry, incorporating maximum climatological water deficit for site effects, with a mean uncertainty of 19.1% and a mean bias of -4.8%. While the mean uncertainty is roughly 2.3% greater than that of the Chave2014 model, this model demonstrates more consistent uncertainties across tree size and delivers less biased estimates of H (with a reduction of 8.23%). In summary, recognizing the errors in H measurements from forest inventory methods is vital, as they can propagate into the allometries they inform. This study underscores the potential of TLS for accurate H and D measurements in tropical rainforests, essential for refining tree allometries.

Exploration of Materials for Three-Dimensional NMR Microcoil Production via CNC Micromilling and Laser Etching.

The excellent versatility of 5-axis computer numerical control (CNC) micromilling has led to its application for prototyping NMR microcoils tailored to mass-limited samples (reducing development time and cost). However, vibrations during 5-axis milling can hinder the creation of complex 3D volume microcoils (i.e., solenoids and saddle coils). To address these limitations, a high-resolution NSCNC ELARA 4-axis milling machine was developed with the extra precision required for making complex 3D volume microcoils. Upon investigating the performance of resonators made with various copper-coated dielectrics, resonators with poly(methyl methacrylate) (PMMA) provided the best SNR/line shape. Thus, complex 1.7 mm microcoil designs were machined from Cu-coated PMMA. A milled 6.4 mm solenoid also provided 6.6× the total carbon signal for a 13C-labeled broccoli seed compared to a commercial inverse 5 mm NMR probe (demonstrating potential for larger coil designs). However, the manufacture of coils <1.7 mm with copper-coated PMMA rods was challenging as ∼0.5 mm of remaining PMMA was needed to retain their structural integrity. To manufacture smaller microcoils, both a solenoid and saddle coil (both with 1 mm O.D., 0.1 mm thick walls) were etched from Cu-coated glass capillaries using a UV picosecond laser that was mounted onto an NSCNC 5-axis MiRA7L. Both resonators showed excellent signal and identified a wide range of metabolites in a 13C-labeled algae extract, while the solenoid was further tested on two copepod egg sacs (∼4 µg of total sample). In summary, the flexibility to prototype complex microcoils in-house allows laboratories to tailor microcoils to specific mass-limited samples while avoiding the costs of cleanrooms.

Assessment of the bony resection margin distance in bone-invasive oral cancer using laser-induced breakdown spectroscopy.

OBJECTIVES: Inadequate resection margins of less than 5 mm impair local tumor control. This weak point in oncological safety is exacerbated in bone-infiltrating tumors because rapid bone analysis procedures do not exist. This study aims to assess the bony resection margin status of bone-invasive oral cancer using laser-induced breakdown spectroscopy (LIBS). MATERIALS AND METHODS: LIBS experiments were performed on natively lasered, tumor-infiltrated mandibular cross-sections from 10 patients. In total, 5,336 spectra were recorded at defined distances from the tumor border. Resection margins < 1 mm were defined as very close, from 1-5 mm as close, and > 5 mm as clear. The spectra were histologically validated. Based on the LIBS spectra, the discriminatory power of potassium (K) and soluble calcium (Ca) between bone-infiltrating tumor tissue and very close, close, and clear resection margins was determined. RESULTS: LIBS-derived electrolyte emission values of K and soluble Ca as well as histological parameters for bone neogenesis/fibrosis and lymphocyte/macrophage infiltrates differ significantly between bone-infiltrating tumor tissue spectra and healthy bone spectra from very close, close, and clear resection margins (p < 0.0001). Using LIBS, the transition from very close resection margins to bone-infiltrating tumor tissue can be determined with a sensitivity of 95.0%, and the transition from clear to close resection margins can be determined with a sensitivity of 85.3%. CONCLUSIONS: LIBS can reliably determine the boundary of bone-infiltrating tumors and might provide an orientation for determining a clear resection margin. CLINICAL RELEVANCE: LIBS could facilitate intraoperative decision-making and avoid inadequate resection margins in bone-invasive oral cancer.

Investigation of a hyperspectral Scanning Laser Optical Tomography setup for label-free cell identification.

The development of non-destructive, tomographic imaging systems is a current topic of research in biomedical technologies. One of these technologies is Scanning Laser Optical Tomography (SLOT), which features a highly modular setup with various contrast mechanisms. Extending this technology with new acquisition mechanisms allows us to investigate untreated and non-stained biological samples, leaving their natural biological physiology intact. To enhance the development of SLOT, we aimed to extend the density of information with a significant increase of acquisition channels. This should allow us to investigate samples with unknown emission spectra and even allow for label-fee cell identification. We developed and integrated a hyperspectral module into an existing SLOT system. The adaptations allow for the acquisition of three-dimensional datasets containing a highly increased information density. For validation, artificial test objects were made from fluorescent acrylic and acquired with the new hyperspectral setup. In addition, measurements were made on two different human cell spheroids with an unknown spectra, to test the possibilities of label-free cell identification. The validation measurements of the artificial test target show the expected results. Furthermore, the measurements of the biological cell spheroids show small variations in their tomographic spectrum that allow for label-free cell type differentiation. The results of the biological sample demonstrate the potential of label-free cell identification of the newly developed setup.

An eight-year retrospective study on the clinical outcomes of laser surface-treated implants.

PURPOSE: To retrospectively evaluate peri-implant bone loss and health status associated with the long-term use of laser surface-treated implants. METHODS: For control study, total of 23 titanium ASTM F136 grade 23 implants were placed in the edentulous molar area of the mandible. When the Implant Stability Quotient (ISQ) ≥ 70 and insertion torque value (ITV) ≥ 35-50 Ncm at the insertion site, an immediate provisional restoration was connected to the implant within a week after surgery. The definitive restorations were placed 2 months after surgery for all implants. 13 implants were immediately loaded, while 10 implants were conventionally loaded. For comparative study, Radiographs were taken from third years for and then annually for the subsequent eight years to monitor marginal bone loss. RESULTS: After eight year of implant installation, the average change in vertical bone loss was 0.009 mm (P < 0.001), while the average change in horizontal bone loss 8 year after implant placement was 0.026 mm (P < 0.001). The mean marginal bone loss was < 0.2 mm on average. CONCLUSIONS: In this retrospective study, laser-treated implants exhibit a low rate of bone absorption around the implants.

Experimental study of laser scattering protection system for low-speed aircraft.

This study introduces a laser scattering system to protect a low-speed aircraft. Scattering was selected to reduce the laser's intensity targeting the sensor of an aircraft and simultaneously maintaining the functionality of aircraft optics. Mie scattering, known for effectively decreasing short-wave infrared light, was employed by utilizing water aerosols having a diameter of 1 to 5 µm. Experimental results regarding the decrease of the laser intensity via scattering confirmed that the theoretical and experimental values resulted in a similar decrease rate under static conditions. To validate the theoretical values, the path length, which the laser passing through water aerosols, was changed. To assess the system's feasibility in flow conditions, a low-speed wind tunnel was employed to generate two flow speeds: 5.5 m/s and 17.6 m/s. Remarkably, the reduction of laser intensity was only affected by the path length, and was somewhat unaffected regardless of flow speed and the uniformity of the flow, only to the path length. In all cases, the initial laser intensity was set to 10 mW. Under static conditions, the intensity dropped to 8.21 mW, showing a decrease of 17.9%. In flow conditions of 5.5 m/s, 17.6 m/s, and in distorted flow, the laser intensity decreased by 18.3%, 18.1%, and 18% respectively. As a preliminary study, these results demonstrate the system's capability to protect a low-speed aircraft targeted by lasers even under dynamic flow conditions, may suggest a possibility of providing a practical defence solution.

Investigations of Astrocyte Calcium Signaling and Imaging with Classical and Nonclassical Light.

The application of light in studying and influencing cellular behavior with improved temporal and spatial resolution remains a key objective in fields such as chemistry, physics, medicine, and engineering. In the brain, nonexcitable cells called astrocytes play essential roles in regulating homeostasis and cognitive function through complex calcium signaling pathways. Understanding these pathways is vital for deciphering brain physiology and neurological disorders like Parkinson's and Alzheimer's. Despite challenges in selectively targeting astrocyte signaling pathways due to shared molecular equipment with neurons, recent advancements in laser technology offer promising avenues. However, the effort to use laser light properties to study astroglial cell function is still limited. This work aims to exploit an in-depth pharmacological analysis of astrocyte calcium channels to determine the physiological mechanism induced by exposure to classical nanosecond-pulsed light. We herein report molecular clues supporting the use of visible-nanosecond laser pulses as a promising approach to excite primary rat neocortical astrocytes and unprecedentedly report on the implementation of entangled two-photon microscopy to image them.

Laser-assisted bioprinting of targeted cartilaginous spheroids for high density bottom-up tissue engineering.

Multicellular spheroids such as microtissues and organoids have demonstrated great potential for tissue engineering applications in recent years as these 3D cellular units enable improved cell-cell and cell-matrix interactions. Current bioprinting processes that use multicellular spheroids as building blocks have demonstrated limited control on post printing distribution of cell spheroids or moderate throughput and printing efficiency. In this work, we presented a laser-assisted bioprinting approach able to transfer multicellular spheroids as building blocks for larger tissue structures. Cartilaginous multicellular spheroids formed by human periosteum derived cells (hPDCs) were successfully bioprinted possessing high viability and the capacity to undergo chondrogenic differentiation post printing. Smaller hPDC spheroids with diameters ranging from ∼100 to 150µm were successfully bioprinted through the use of laser-induced forward transfer method (LIFT) however larger spheroids constituted a challenge. For this reason a novel alternative approach was developed termed as laser induced propulsion of mesoscopic objects (LIPMO) whereby we were able to bioprint spheroids of up to 300µm. Moreover, we combined the bioprinting process with computer aided image analysis demonstrating the capacity to 'target and shoot', through automated selection, multiple large spheroids in a single sequence. By taking advantage of target and shoot system, multilayered constructs containing high density cell spheroids were fabricated.

In vitro evaluation of the biocompatibility and bioactivity of a SLM-fabricated NiTi alloy with superior tensile property.

Because nickel-titanium (NiTi) alloys have unique functions, such as superelasticity, shape memory, and hysteresis similar to bone in the loading-unloading cycles of their recoverable deformations. They likely offer good bone integration, a low loosening rate, individual customization, and ease of insertion. Due to the poor processability of NITI, traditional methods cannot manufacture NiTi products with complex shapes. Orthopedic NiTi implants need to show an adequate fracture elongation of at least 8%. Additive manufacturing can be used to prepare NiTi implants with complex structures and tunable porosity. However, as previously reported, additively manufactured NiTi alloys could only exhibit a maximum tensile fracture strain of 7%. In new reports, a selective laser melting (SLM)-NiTi alloy has shown greater tensile strain (15.6%). Nevertheless, due to the unique microstructure of additive manufacturing NiTi that differs from traditional NITI, the biocompatibility of SLM-NITI manufactured by this new process requires further evaluation In this study, the effects of the improved NiTi alloy on bone marrow mesenchymal stem cell (BMSC) proliferation, adhesion, and cell viability were investigated via in vitro studies. A commercial Ti-6Al-4V alloy was studied side-by-side for comparison. Like the Ti-6Al-4V alloy, the SLM-NiTi alloy exhibited low cytotoxicity toward BMSCs and similar effect on cell adhesion or cell viability. This study demonstrates that the new SLM-NiTi alloy, which has exhibited improved mechanical properties, also displays excellent biocompatibility. Therefore, this alloy may be a superior implant material in biomedical implantation.

Selective nanosecond laser removal of retinal pigment epithelium for cell therapy.

Retinal pigment epithelial (RPE) cells play a crucial role in the health of the retina, and their dysfunction is associated with various ocular diseases. The transplantation of RPE cells has been proposed as a potential treatment for numerous degenerative diseases, including geographic atrophy from macular degeneration. However, current models to induce RPE damage in animal models prior to transplantation involve mechanical scraping, chemical administration, or laser photocoagulation techniques, which can damage the overlying neurosensory retina. This study aims to investigate the feasibility and efficacy of nanosecond duration laser treatment to safely remove large areas of RPE cells without causing damage to the adjacent tissue or affecting the retinal architecture. Twelve pigmented rabbits were treated with a nanosecond laser on each eye at a laser energy ranging from 200 to 800 nJ with a treated area of 5 × 5 mm2. Human induced pluripotent stem cells-differentiated to RPE (hiPSC-RPE) cells labeled with indocyanine green (ICG), an FDA approved dye, were transplanted subretinally into the damaged RPE areas at day 14 post-laser treatment. The RPE atrophy and hiPSC-RPE cell survival was evaluated and monitored over a period of 14 days using color photography, fluorescein angiography (FA), photoacoustic microscopy (PAM), and optical coherence tomography (OCT) imaging. All treated eyes demonstrated focal RPE loss with a success rate of 100%. The injured RPE layers and the transplanted hiPSC-RPE cells were visualized in three dimensions using PAM and OCT. By performing PAM at an optical wavelength of 700 nm, the location of hiPSC-RPE cells were identified and distinguished from the surrounding RPE cells, and the induced PA signal increased up to 18 times. Immunohistochemistry results confirmed the grafted hiPSC-RPE replaced regions of RPE damage. This novel technique has the potential to serve as an animal model of RPE degeneration, to improve models of RPE transplantation, and may help accelerate translation of this therapeutic strategy for clinical use.

The cutting-edge roles of lasers in endodontics: A bibliometric and scientometric analysis of the 100 most-cited articles.

PURPOSE: This bibliometric and scientometric analysis aimed to delve into the forefront roles of lasers in endodontics from 1990 to 2024. METHODS: A comprehensive electronic search was conducted using "Clarivate Analytics Web of Science, All Databases" to retrieve the most-cited articles pertaining to the topic. These articles were then ranked in descending order according to their citation counts and the top 100 were selected for further analysis. Parameters including citation density, publication year, journal, journal impact factor (IF), country, institution, author, study design, study field, evidence level, laser type, and keywords were meticulously analyzed. RESULTS: The mean and standard deviations of total citation and citation density were 106.47 ± 65.76 and 7.61 ± 5.13, respectively. Positive and negative correlations were found between the number of citations and citation density and age of publication. While the mean number of citations was significantly higher in the period 2001-2010 compared to the other periods (P < 0.05), values were similar between the periods 1990-2000 and 2011-2014 (P > 0.05). Articles were mainly published in the Journal of Endodontics. The most productive country, institutions, and author were the United States, the University of Showa, and Koukichi Matsumoto. Diode and Er: YAG lasers were commonly investigated. Ex vivo studies were mainly performed followed by in vitro ones. The main study field was "antimicrobial effect". Among keywords, "photodynamic therapy" was used more frequently. CONCLUSION: Lasers are predominantly utilized to leverage their antimicrobial efficacy. Advancements in technology will lead to improvements in the properties of lasers, thereby enhancing the disinfection of the root canal system.

Harmonic Generation in Molecular Ag2S Plasma.

The molecular laser-induced plasma (LIP) produced during the ablation of silver sulfide (Ag2S) was used as a medium for high-order harmonic generation in the extreme ultraviolet range. The role of LIP formation, the plasma components, and the geometry of plasma in the harmonic conversion efficiency was analyzed. We also analyzed the influence of the driving pulses (chirp, single-color pump, two-color pump, and delay between heating and converting pulses) on the harmonic yield in Ag2S LIP. The application of molecular plasma was compared with the application of atomic plasma, which comprised similar metallic elements (Ag) as well as other metal LIPs. The harmonics from the Ag2S LIP were 4 to 10 times stronger than those from the Ag LIP. The harmonics up to the 59th order were achieved under the optimal conditions for the molecular plasma.

Enhancing Bactericidal Properties of Ti6Al4V Surfaces through Micro and Nano Hierarchical Laser Texturing.

Orthopedic and dental implants made from Ti6Al4V are widely used due to their excellent mechanical properties and biocompatibility. However, the long-term performance of these implants can be compromised by bacterial infections. This study explores the development of hierarchically textured surfaces with enhanced bactericidal properties to address such challenges. Hierarchical surface structures were developed by combining microscale features produced by a microsecond laser and superimposed submicron features produced using a femtosecond laser. Microscale patterns were produced by the pulsed laser surface melting process, whereas submicrometer laser-induced periodic surface structures were created on top of them by femtosecond laser processing. Escherichia coli bacterial cells were cultured on the textured surface. After 24 h, a staining analysis was performed using SYTO9 and PI dyes to investigate the samples with a confocal microscope for live dead assays. Results showed bacterial colony formation onto the microscale surface textures with live bacterial cells, whereas the hierarchical surface textures display segregated and physically damaged bacterial cell attachments on surfaces. The hierarchical surface textures showed ∼98% dead bacterial cells due to the combined effect of its multiscale surface features and oxide formation during the laser processing steps. The efficacy of hierarchical surface textures in enhancing the antibacterial behavior of Ti6Al4V implants is evident from the conducted research. Such laser-based surface treatments can find potential applications in different industrial sectors.

A pilot study using the LASCA technique to analyze stress using heart rate variability.

In the quest to uncover biological cues that help explain organic changes brought on by an external stimulus, like stress, new technologies have become necessary. The Laser Speckle Contrast Analysis (LASCA) approach is one of these technologies that may be used to analyze biological data, including respiratory rate (RR) intervals, and then use the results to determine heart rate variability (HRV Thus, to evaluate the stress brought on by physical activity, this study used the LASCA approach. A stress induction procedure involving physical exertion was employed, and the results were compared to other established techniques (cortisol analysis and ECG signal) to verify the LASCA methodology as a tool for measuring HRV and stress. The study sample comprised 27 willing participants. The technique involving LASCA allowed for the non-invasive (non-contact) acquisition of HRV and the study of stress. Furthermore, it made it possible to gather pertinent data, such as recognizing modifications to the thermoregulation, peripheral vasomotor tonus, and renin-angiotensin-aldosterone systems that were brought on by elevated stress and, as a result, variations in HRV readings.

Laser microdissection system based on structured light modulation dual cutting mode and negative pressure adsorption collection.

Laser microdissection technology is favored by biomedical researchers for its ability to rapidly and accurately isolate target cells and tissues. However, the precision cutting capabilities of existing laser microdissection systems are hindered by limitations in overall mechanical movement accuracy, resulting in suboptimal cutting quality. Additionally, the use of current laser microdissection systems for target acquisition may lead to tissue burns and reduced acquisition rates due to inherent flaws in the capture methods. To address these challenges and achieve precise and efficient separation and capture of cellular tissues, we integrated a digital micromirror device (DMD) into the existing system optics to modulate spatial light. This allows the system to not only implement the traditional point scanning cutting method but also utilize the projection cutting method.We have successfully cut various patterns on commonly used laser microdissection materials such as PET films and mouse tissues. Under projection cutting mode, we were able to achieve precise cutting of special shapes with a diameter of 7.5 micrometers in a single pass, which improved cutting precision and efficiency. Furthermore, we employed a negative pressure adsorption method to efficiently collect target substances. This approach not only resulted in a single-pass capture rate exceeding 90% for targets of different sizes but also enabled simultaneous capture of multiple targets, overcoming the limitations of traditional single-target capture and enhancing target capture efficiency, and avoiding potential tissue damage from lasers.In summary, the integration of the digital micromirror device into laser microdissection systems significantly enhances cutting precision and efficiency, overcoming limitations of traditional systems. This advancement demonstrates the accuracy and effectiveness of laser microdissection systems in isolating and capturing biological tissues, highlighting their potential in medical applications.

Enhanced quantification of chlorophyll a and its degradation products in olive oil using time-resolved laser-induced fluorescence fingerprint analysis.

Potential errors in the fluorescence analysis of chlorophylls and their degradation products, primarily due to spectral overlap and inner filter, are widely acknowledged. This study aimed to devise a sensitivity-enhanced technique for the concurrent quantification of chlorophyll a and its degradation products while minimizing effects from type-B chlorophylls. Initially, a time-resolved laser-induced fluorescence spectroscopic system was designed and tested on stardard chlorophyll samples. The origins, implications, and mitigation strategies of spectral overlap and the inner filter effect on the measured fluorescence intensity were thoroughly examined. Then, this methodology was proved to be efficacious within complex liquid matrices derived from olive oil. The experimental outcomes not only shed additional light on the mechanisms of chlorophyll fluorescence overlap and the inner filter effect, but also establish a general framework for developing spectrally and timely resolved fluorescence fingerprint analysis for the simultaneous quantification of chlorophylls and their degradation products at high concentrations.

On-demand Opto-Laser activatable nanoSilver ThermoGel for treatment of full-thickness diabetic wound in a mouse model.

Patients suffering from diabetes mellitus are prone to develop diabetic wounds that are non-treatable with conventional therapies. Hence, there is an urgent need of hour to develop the therapy that will overcome the lacunas of conventional therapies. This investigation reports the Quality by Design-guided one-pot green synthesis of unique Opto-Laser activatable nanoSilver ThermoGel (OL→nSil-ThermoGel) for hyperthermia-assisted treatment of full-thickness diabetic wounds in mice models. The characterization findings confirmed the formation of spherical-shaped nanometric Opto-Laser activatable nanoSilver (30.75 ± 2.7 nm; ∆T: 37 ± 0.2 °C â†’ 66.2 ± 0.1 °C; at 1.8 W/cm2 NIR laser density). The findings indicated acceptable in vitro cytocompatibility and significant keratinocyte migration (95.04 ± 0.07 %) activity of OL→nSil towards HaCaT cells. The rheological data of OL→nSil hybridized in situ thermoresponsive gel (OL→nSil-ThermoGel) showed the gelling temperature at 32 ± 2 °C. In vivo studies on full-thickness diabetic wounds in a Mouse model showed OL→nSil-ThermoGel accelerated wound closure (94.42 ± 1.03 %) and increased collagen synthesis, angiogenesis, and decreased inflammatory markers. Similarly, immunohistochemistry study showed significant angiogenesis and faster phenotypic switching of fibroblasts to myofibroblasts in OL→nSil-ThermoGel treated diabetic wounds. Histological evaluation revealed a marked rise in keratinocyte migration, organized collagen deposition, and early regeneration of the epithelial layer compared to the diabetic wound control. In conclusion, the OL→nSil-ThermoGel modulates the cytokines, re-epithelialization, protein expression, and growth factors, thereby improving the repair and regeneration of diabetic wounds in mice.

Highly Sensitive Biosensors Based on All-PEDOT:PSS Organic Electrochemical Transistors with Laser-Induced Micropatterning.

Recent advances in numerous biological applications have increased the accuracy of monitoring the level of biologically significant analytes in the human body to manage personal nutrition and physiological conditions. However, despite promising reports about costly wearable devices with high sensing performance, there has been a growing demand for inexpensive sensors that can quickly detect biological molecules. Herein, we present highly sensitive biosensors based on organic electrochemical transistors (OECTs), which are types of organic semiconductor-based sensors that operate consistently at low operating voltages in aqueous solutions. Instead of the gold or platinum electrode used in current electrochemical devices, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was used as both the channel and gate electrodes in the OECT. Additionally, to overcome the patterning resolution limitations of conventional solution processing, we confirmed that the irradiation of a high-power IR laser (λ = 1064 nm) onto the coated PEDOT:PSS film was able to produce spatially resolvable micropatterns in a digital-printing manner. The proposed patterning technique exhibits high suitability for the fabrication of all-PEDOT:PSS OECT devices. The device geometry was optimized by fine-tuning the gate area and the channel-to-gate distance. Consequently, the sensor for detecting ascorbic acid (vitamin C) concentrations in an electrolyte exhibited the best sensitivity of 125 µA dec-1 with a limit of detection of 1.3 µM, which is nearly 2 orders of magnitude higher than previous findings. Subsequently, an all-plastic flexible epidermal biosensor was established by transferring the patterned all-PEDOT:PSS OECT from a glass substrate to a PET substrate, taking full advantage of the flexibility of PEDOT:PSS. The prepared all-plastic sensor device is highly cost-effective and suitable for single-use applications because of its acceptable sensing performance and reliable signal for detecting vitamin C. Additionally, the epidermal sensor successfully obtained the temporal profile of vitamin C in the sweat of a human volunteer after the consumption of vitamin C drinks. We believe that the highly sensitive all-PEDOT:PSS OECT device fabricated using the accurate patterning process exhibits versatile potential as a low-cost and single-use biosensor for emerging bioelectronic applications.

Laser Fabrication of Humidity Sensors on Ethanol-Soaked Polyimide for Fully Contactless Respiratory Monitoring.

Humidity-sensor-based fully contactless respiratory monitoring can eliminate the discomfort and infection risks associated with any wearable device. However, challenges in the facile fabrication of highly sensitive humidity sensors continue to hinder their widespread application for fully contactless respiratory monitoring. In this study, we introduce a simple method to fabricate highly sensitive humidity sensors. Our method employs laser-induced graphene (LIG) on an ethanol-soaked polyimide (PI) film as the electrode of the humidity sensor. The ethanol-soaked PI between adjacent LIG electrodes functions as the sensing material, enabling ion-conductive humidity sensing. Compared to the LIG humidity sensors fabricated on untreated PI films, LIG humidity sensors fabricated on ethanol-soaked PI films exhibit superior performance with higher linearity (R2 = 0.9936), reduced hysteresis (ΔH = 5.1% RH), and increased sensitivity (0.65%/RH). Notably, the LIG humidity sensor fabricated on the ethanol-soaked PI film can detect a person's breathing from a distance of 30 cm, a capability not achieved by sensors fabricated on untreated PI films. Moreover, incorporating these LIG humidity sensors into an array further enhances both the detection distance and the sensitivity for respiratory monitoring. Experimental results demonstrate that the LIG humidity sensor array can be employed for fully contactless on-bed respiration monitoring and for continuous, fully contactless monitoring of the respiratory rate during treadmill exercise. These results highlight the great potential of our LIG humidity sensors for various practical applications in medicine and sports.

Hydrogen/Deuterium Exchange Reaction Rate of Cytochrome c Determined by Droplet Collision Atmospheric Pressure Infrared Laser Ablation Mass Spectrometry.

The hydrogen/deuterium (H/D) exchange rate is an optimal measure for studying the structures and dynamics of hydrogen bonding systems, as it reflects the molecular contact environment and the strength of the hydrogen bonds. A method for rapid measurement of the H/D exchange reaction rates is required to examine the intermolecular environments of molecules in solutions. We developed a droplet collision atmospheric pressure infrared laser ablation mass spectrometry technique for this purpose. We obtained the H/D exchange reaction rate of cytochrome c in a methanol/H2O·D2O solution. We revealed that the first hydration shell of the cytochrome c molecule hinders the penetration of D2O to the surface of the molecule from the rates, which provides a novel method to investigate solution structures by a mass-spectrometric method. The droplet-collision mass spectrometry method developed in the present study can be extended to research on the molecular interactions in solutions, such as the mutual interactions of protein molecules, which are of importance in living cells.