Direct Physical Contact Research Articles

Development and performance investigation of a novel ultrasonic-assisted non-contact membrane distillation process to prevent membrane fouling

A novel non-contact membrane distillation (NCMD) process is proposed that prevents membrane fouling by preventing direct physical contact between the feed and membrane. The feed channel of the NCMD module is equipped with an ultrasonic transducer that provides high-frequency mechanical oscillations to the feed film, which forms a fine mist of droplets and water column. Experiments are conducted to determine the feed height required to maximize the evaporation rate, and the effects of feed temperature, flow rate, and ultrasonic power on the permeation flux. The results reveal that the highest permeation flux occurs at a feed height of 20 mm, and an increase in the feed height and flow rate decreases the ultrasonic cavitation effect, while a higher feed temperature and ultrasonic power significantly increases the permeation flux. At the feed temperature of 60 °C, feed flow rate of 1.0 L/min, and ultrasonic current of 600 mA, the permeation flux is 6.3 kg/m2h, which is 8.4 times greater than that of the NCMD process without ultrasonic treatment. The corresponding specific energy consumptions with and without the ultrasonication are 647 and 6028 kWh/m3, respectively. Moreover, the long-term experimental results indicate that the proposed system is unaffected by high feed concentrations.

Drug resistant pancreatic cancer cells exhibit altered biophysical interactions with stromal fibroblasts in imaging studies of 3D co-culture models

Interactions between tumor and stromal cells are well known to play prominent roles in progression of pancreatic ductal adenocarcinoma (PDAC). As knowledge of stromal crosstalk in PDAC has evolved, it has become clear that cancer associated fibroblasts can play both tumor promoting and tumor suppressive roles through a combination of paracrine crosstalk and juxtacrine interactions involving direct physical contact. Another major contributor to dismal survival statistics for PDAC is development of resistance to chemotherapy drugs, though less is known about how the acquisition of chemoresistance impacts upon tumor-stromal crosstalk. Here, we use time lapse imaging and image analysis to study how co-culture geometry impacts interactions between epithelial and stromal cells. We show that extracellular matrix (ECM) overlay cultures in which stromal cells (pancreatic stellate cells, or normal human fibroblasts) are placed adjacent to PDAC cells (PANC1) result in direct heterotypic cell adhesions accompanied by dramatic fibroblast contractility. We analyze these interactions in co-cultures using particle image velocimetry (PIV) analysis to quantify cell velocities over the course of time lapse movie sequences. We further contrast co-cultures of PANC1 with those containing a drug resistant subline (PANC1-OR) previously established in our lab and find that heterotypic cell–cell interactions are suppressed in the latter relative to the parental line. We use RNA-seq and bioinformatics analysis to identify differential gene expression in PANC1 and PANC1-OR, which shows that negative regulation of cell adhesion molecules, consistent with increased epithelial mesenchymal transition (EMT), is also correlated with reduction in the hetrotypic cell–cell contact necessary for the contractile behavior observed in drug naïve cultures. Overall these findings elucidate the role of drug-resistance in inhibiting an avenue of stromal crosstalk which is associated with tumor suppression and also help to establish cell culture conditions useful for further mechanistic investigation.

Understanding Excipient-Induced Crystallization of Spray-Dried Amorphous Solid Dispersion

This study investigates the compatibility of excipients with the model system SDI-X and their role in the induced crystallization of the amorphous compound-X in tablet formulations. We aimed to establish a straightforward and practical screening approach for evaluating excipient-induced crystallization of SDI in tablet matrices. Three methodologies—binary powder mixture, binary compact, and bilayer tablets—were employed to qualitatively and quantitatively evaluate the recrystallization of SDI-X with various excipients under accelerated storage conditions. The results demonstrated that binary compacts, providing direct physical contact between SDI-X and excipients, are superior in reflecting realistic drug-excipient contact within pharmaceutical tablets, enabling a more accurate assessment of excipient-induced crystallization for SDI-X. In contrast, the broadly used conventional binary blends can significantly underestimate this risk due to insufficient proximity. In addition, the bilayer tablets further confirmed that crystallization initiates at the contact surface between SDI-X and the excipients. The study highlighted that not only hygroscopicity but also the type of excipient and its physical contact with SDI-X significantly influence the recrystallization extent and rate of SDI-X. Interestingly, less hygroscopic diluents such as mannitol and lactose induced much higher levels of crystallization of SDIs, contrary to expectations based on moisture content alone. This suggests that the excipient type and contact surface are more critical in inducing recrystallization than just the level of moisture. The findings emphasize the need for careful excipient selection, study design, and sample preparation to enable appropriate assessments of SDI-excipient compatibility.

Platelet and epithelial cell interations can be modeled in cell culture, and are not affected by dihomo-gamma-linolenic acid.

Increasing evidence is implicating roles for platelets in the development and progression of ovarian cancer, a highly lethal disease that can arise from the fallopian tubes, and has no current method of early detection or prevention. Thrombosis is a major cause of mortality of ovarian cancer patients suggesting that the cancer alters platelet behavior. The objective of this study was to develop a cell culture model of the pathological interactions of human platelets and ovarian cancer cells, using normal FT epithelial cells as a healthy control, and to test effects of the anti-platelet dihomo-gamma-linolenic acid (DGLA) in the model. Both healthy and cancer cells caused platelet aggregation, however platelets only affected spheroid formation by cancer cells and had no effect on healthy cell spheroid formation. When naturally-formed spheroids of epithelial cells were exposed to platelets in transwell inserts that did not allow direct interactions of the two cell types, platelets caused increased size of the spheroids formed by cancer cells, but not healthy cells. When cancer cell spheroids formed using magnetic nanoshuttle technology were put in direct physical contact with platelets, the platelets caused spheroid condensation. In ovarian cancer cells, DGLA promoted epithelial-to-mesenchymal (EMT) transition at doses as low as 100 μM, and inhibited metabolic viability and induced apoptosis at doses ≥150 μM. DGLA doses ≤150 μM used to avoid direct DGLA effects on cancer cells, had no effect on the pathological interactions of platelets and ovarian cancer cells in our models. These results demonstrate that the pathological interactions of platelets with ovarian cancer cells can be modeled in cell culture, and that DGLA has no effect on these interactions, suggesting that targeting platelets is a rational approach for reducing cancer aggressiveness and thrombosis risk in ovarian cancer patients, however DGLA is not an appropriate candidate for this strategy.

Enhancing food crop classification in agriculture through dipper throat optimization and deep learning with remote sensing

Remote sensing images (RSIs), a keystone of modern agricultural technology, refer to spectral or visual data captured from drones, satellites, or aircraft without direct physical contact with the Earth's surface. These images provide a wide-ranging view of agricultural landscapes, providing valuable insights into land use, crop health, and environmental conditions. Agricultural food crop classification, a vital application within precision agriculture, includes the detection and classification of different crops cultivated in a certain region. Traditionally reliant on manual techniques, the development of technologies, particularly the incorporation of RSIs, has revolutionized this process. Agricultural food crop classification has become more sophisticated and automated by harnessing the wealth of data received from RS, which facilitates precise management and monitoring of crops on a large scale. Deep learning (DL), a branch of artificial intelligence, plays a more effective role in these synergies. The incorporation of DL into the RSI analysis enables high-precision and efficient detection of various crop types, assisting more informed decision-making in agriculture. This study proposes a new Dipper Throat Optimization Algorithm with Deep Learning based Food Crop Classification (DTOADL-FCC) algorithm using Remote Sensing Imaging for Agricultural Resource Management. The DTOADL-FCC method aims to apply DL algorithms for the classification of different crop types. In the DTOADL-FCC method, fully convolutional network (FCN) based segmentation process is performed. Next, the DTOADL-FCC method exploits the SE-ResNet model for learning intrinsic and complex features. The DTOADL-FCC method makes use of DTOA for the hyperparameter tuning process. Lastly, the classification of crop types takes place using the extreme learning machine (ELM) model. The study utilizes mathematical formulations including activation functions, loss functions, fitness calculations, and iterative update processes. A brief set of simulations showcases that the DTOADL-FCC method achieves remarkable performance over other techniques with much improved results.

Exploring modes of microbial interactions with implications for methane cycling.

Methanotrophs are the sole biological sink of methane. Volatile organic compounds (VOCs) produced by heterotrophic bacteria have been demonstrated to be a potential modulating factor of methane consumption. Here, we identify and disentangle the impact of the volatolome of heterotrophic bacteria on the methanotroph activity and proteome, using Methylomonas as model organism. Our study unambiguously shows how methanotrophy can be influenced by other organisms without direct physical contact. This influence is mediated by VOCs (e.g. dimethyl-polysulphides) or/and CO2 emitted during respiration, which can inhibit growth and methane uptake of the methanotroph, while other VOCs had a stimulating effect on methanotroph activity. Depending on whether the methanotroph was exposed to the volatolome of the heterotroph or to CO2, proteomics revealed differential protein expression patterns with the soluble methane monooxygenase being the most affected enzyme. The interaction between methanotrophs and heterotrophs can have strong positive or negative effects on methane consumption, depending on the species interacting with the methanotroph. We identified potential VOCs involved in the inhibition while positive effects may be triggered by CO2 released by heterotrophic respiration. Our experimental proof of methanotroph-heterotroph interactions clearly calls for detailed research into strategies on how to mitigate methane emissions.

Developing Bluetooth phonocardiogram for detecting heart murmurs using hybrid MFCC and LSTM

Cardiovascular disease is a leading global cause of mortality. Most stethoscopes still necessitate the use of tubing, which entails direct physical contact between the healthcare provider and patient. The stethoscope can serve as a means of transmission if it is utilized on individuals who have been diagnosed with airborne and droplet-borne infectious illnesses. A prototype was created to capture heart sounds using a Phonocardiography (PCG) device over website-based Bluetooth connectivity. This approach offers the benefits of being cost-effective, facilitating computer-aided diagnostics, and being wearable. In addition, the primary significance of this study resides in the identification of heart sound irregularities caused by cardio dynamic abnormalities of the heart valves, known as murmurs. The heart sound categorization process utilizes a machine learning model that involves extracting 25 Mel frequency cepstral coefficients (MFCC) as features. The model employs a hybrid approach combining convolutional neural network and long short-term memory (CNN-LSTM) techniques. The research findings indicate that the suggested model achieves an average accuracy rate of 95.9% over five distinct categories, i.e., normal, atrial stenosis, mitral regurgitation, mitral stenosis, and mitral valves prolapse. Further study can be conducted on hardware development by incorporating an infrared sensor at the fingertip of the stethoscope.

Technology Acceptance Analysis Using UTAUT: A Study of QRIS Acceptance during the Pandemic

Background: The COVID-19 pandemic situation has compelled society to practice physical distancing. One of the government's efforts is to encourage the use of the QRIS payment method to minimize direct physical contact during transactions. Objective: The purpose of this research is to analyze the primary driving factors in the adoption of QRIS technology. The research urgency is to determine the most contributing predictor from the variables within the UTAUT model among the people of Jabodetabek. Methods: This research used the quantitative method by conducting an online survey among 384 respondents distributed across the Jabodetabek region. The sampling technique utilized was non-purposive sampling with criteria including domicile, age, reasons, frequency, and experience of QRIS usage. Conclusion: The results of the factor analysis test indicate that the performance expectancy and effort expectancy variables are combined into one variable, while the social influence variable is divided into two independent variables. The research findings reveal that the perceived risk variable is the predictor with the most significant contribution in the context of the pandemic situation. Future researchers are expected to be able to develop the research model in other contexts with different goals.

Interaction, Management and Response of Healthcare Workers Towards Workplace Violence Events

Objective: To evaluate the interaction, management and response towards WPV events by HCW’s of emergency department Methodology: We conducted this cross-sectional study using World Health Organization’s tool to collect quantitative data on workplace violence (WPV) amongst universally sampled 164 health professionals working in an emergency department at Nishtar hospital Multan from June-August 2019 after taking an inform consent. All physically present health professionals who have been working there including paramedics, doctors, & nurses, were part of research. Results: Out of 164 healthcare employees, males were ninety-seven while females were sixty-seven. All the subjects said that they work in shifts, anytime between 18h00 (6 PM) and 07h00 (7 AM), and interact with patients/clients during work as well. Only 11% reported that they have routinely direct physical contact (washing, turning, lifting) with patients/clients. When talking about response to the incident, approximately one-third of the participants sought help from association, almost half of the HCW’s reported to their senior staff, 13.5% subject sought help from union, merely 3.5% HCW told the person to stop whereas, 4.5% told family/friends Conclusion: Health professionals working in shifts, and also interacting with patients/clients faced violence and mostly reported to their senior staff, or sought help from their association.

Drug resistant pancreatic cancer cells exhibit altered biophysical interactions with stromal fibroblasts in imaging studies of 3D co-culture models.

Interactions between tumor and stromal cells are well known to play a prominent roles in progression of pancreatic ductal adenocarcinoma (PDAC). As knowledge of stromal crosstalk in PDAC has evolved, it has become clear that cancer associated fibroblasts can play both tumor promoting and tumor suppressive roles through a combination of paracrine crosstalk and juxtacrine interactions involving direct physical contact. Another major contributor to dismal survival statistics for PDAC is development of resistance to chemotherapy drugs. Though less is known about how the acquisition of chemoresistance impacts upon tumor-stromal crosstalk. Here, we use 3D co-culture geometries to recapitulate juxtacrine interactions between epithelial and stromal cells. In particular, extracellular matrix (ECM) overlay cultures in which stromal cells (pancreatic stellate cells, or normal human fibroblasts) are placed adjacent to PDAC cells (PANC1), result in direct heterotypic cell adhesions accompanied by dramatic fibroblast contractility which leads to highly condensed macroscopic multicellular aggregates as detected using particle image velocimetry (PIV) analysis to quantify cell velocities over the course of time lapse movie sequences. To investigate how drug resistance impacts these juxtacrine interactions we contrast cultures in which PANC1 are substituted with a drug resistant subline (PANC1-OR) previously established in our lab. We find that heterotypic cell-cell interactions are highly suppressed in drug-resistant cells relative to the parental PANC1 cells. To investigate further we conduct RNA-seq and bioinformatics analysis to identify differential gene expression in PANC1 and PANC1-OR, which shows that negative regulation of cell adhesion molecules, consistent with increased epithelial mesenchymal transition (EMT), is also consistent with loss of hetrotypic cell-cell contact necessary for the contractile behavior observed in drug naïve cultures. Overall these findings elucidate the role of drug-resistance in inhibiting an avenue of stromal crosstalk which is associated with tumor suppression and also help to establish cell culture conditions useful for further mechanistic investigation.

The Effect of Humidity on the Mass and Unit Cell Volume of Montmorillonite near Room Temperature

Phase equilibria between montmorillonite (Swy-2 from Wyoming, USA) and H2O vapor phase were established by using the humidity buffer technique at 0.1 MPa and room temperature (23 ± 0.5°C). The Relative Humidity (RH; equivalent to the activity of H2O) levels of the system were defined between 6.5% and 97.4% by using six different salt-saturated aqueous solutions. There was no direct physical contact between Swy-2 sample and the buffer solution to prevent any metal ion exchanges between them. The reaction time at each humidity buffer was 10 days, after which the mass of the sample was determined and X-ray powder diffraction spectrum was collected. The experiments were carried out in two directions: one is adsorption (i.e., from low to high RH), and the other is desorption (i.e., from high to low RH), and the equilibrium of the system was demonstrated by the adsorption-desorption reversal experiments in terms of both mass change and crystal parameters (d-001 spacing and unit cell volume). When compared our data with those from previous study for Na-saturated montmorillonite, either synthetic or natural, the Na replacement in the crystal structure favored the retention of water, but only under RH higher than about 62%.

Clinical features and viral load variations of Mpox: a retrospective study in Chongqing, China

PurposeSince May 2022, Mpox has spread extensively outside of Africa, posing a serious threat to the health of people globally, and particularly to the men who have sex with men (MSM) population. Chongqing, a province in Southwest China, has relatively large MSM and people living with HIV (PLWH) populations, presenting conditions conducive to the wide dissemination of Mpox. In this study, we investigated the clinical characteristics of Mpox patients among MSM and PLWH in Chongqing, aiming to inform the development of targeted prevention, control, and treatment strategies for Mpox.MethodWe evaluated the clinical characteristics, travel history, time of onset, distribution and number of skin lesions of Mpox patients admitted to the Chongqing Public Health Medical Center between September 2022 and October 2023. Meanwhile, a series of clinical samples were collected and the pathogen of interest was identified as Mpox virus using quantitative polymerase chain reaction (qPCR). The results were presented in the form of cycle thresholds (Ct), which help to approximate the quantification of viral load.ResultsAs of October 11, 2023, the Chongqing Public Health Medical Center reported a total of nine Mpox virus infections. All the patients identified were male and belonged to the MSM population, among whom seven (77.8%) were living with HIV, and maintained a preserved immune system while achieving viral suppression via effective ART. We observed no discernible clinical differences between MSM with Mpox with or without HIV, and no fatalities were recorded. Viral loads were observed to be higher in samples taken from the skin than those from the throat, nasopharynx, blood, or semen.ConclusionIn this retrospective study, the clinical manifestations of MPXV infection appeared consistent among MSM patients, regardless of HIV status. Elevated MPXV viral loads in the skin and mucosal tissues, particularly at genital and anal sites, indicate that transmission is more likely to occur via direct physical contact as opposed to respiratory pathways or through exposure to bodily fluids.

Workplace Violence Against Nurses in Psychiatric Hospitals in Oman: A cross-sectional multi-centre study.

This study aimed to assess the prevalence of workplace violence (WPV) against nurses in Oman's psychiatric hospitals and explore associated factors. This cross-sectional study was conducted between October and December 2021 and included all tertiary mental healthcare hospitals in Oman (Al Masarra Hospital and Sultan Qaboos University Hospital, Muscat, Oman). The participants completed a sociodemographic survey and a questionnaire on WPV in the health sector. A total of 106 participants (response rate = 80.3%) were included in this study. Most were female (52.8%) and Omani (72.6%) and aged 30-39 years. WPV prevalence was high (90.6%), with verbal (86.8%) and physical violence (57.5%) being the most common types. WPV incidents were more frequent on weekdays (26.4%) and during morning shifts (34%), while 81.1% of the nurses worked in shifts and had direct physical contact with patients (83.0%). The majority (92.5%) were aware of standardised WPV reporting procedures and 89.7% confirmed the presence of such procedures in hospitals. WPV was more prevalent among nurses in inpatient wards (P = 0.047). WPV against nurses in Omani psychiatric hospitals is alarmingly high. Future studies should investigate contributing factors among healthcare providers and emphasise violence prevention by providing staff nurses with effective training to handle violent incidents involving psychiatric patients.

Integrating RGB-thermal image sensors for non-contact automatic respiration rate monitoring

Respiration rate (RR) holds significance as a human health indicator. Presently, the conventional RR monitoring system requires direct physical contact, which may cause discomfort and pain. Therefore, this paper proposes a non-contact RR monitoring system integrating RGB and thermal imaging through RGB-thermal image alignment. The proposed method employs an advanced image processing algorithm for automatic region of interest (ROI) selection. The experimental results demonstrated a close correlation and a lower error rate between measured thermal, measured RGB, and reference data. In summary, the proposed non-contact system emerges as a promising alternative to conventional contact-based approaches without the associated discomfort and pain.

Catch yield and selectivity of a modified scallop dredge to reduce seabed impact.

Global scallop fisheries are economically important but are associated with environmental impacts to seabed communities resulting from the direct physical contact of the fishing gear with the seabed. Gear modifications attempting to reduce this contact must be economically feasible such that the catch numbers for the target species is maintained or increased. This study investigated the outcome of reducing seabed contact on retained catch of scallops and bycatch by the addition of skids to the bottom of the collecting bag of scallop dredges. We used a paired control experimental design to investigate the impact of the gear modification in different habitat types. The modified skid dredge generally caught more marketable scallops per unit area fished compared with the standard dredge (+5%). However, the skid dredge also retained more bycatch (+11%) and more undersize scallops (+16%). The performance of the two dredges was habitat specific which indicates the importance of adjusting management measures in relation to habitat type. To realize the potential environmental benefits associated with the improvement in catchability of this gear modification, further gear modification is required to reduce the catch of undersize scallops and bycatch. Furthermore we advocate that technical gear innovations in scallop dredging need to be part of a comprehensive and effective fisheries management system.

The development of the ultrasonic flowmeter sensors for mass flow rate measurement: A comprehensive review

A two-phase flow measuring device whose measurement system does not disturb the flow pattern, real-time measurement, and non-destructive measurement or non-intrusive model is a typical tool for an ideal situation. One measuring instrument that meets these criteria is an ultrasonic flow meter. Ultrasonic sensors can measure the velocity of fluid flow in pipelines. It has the advantage of high accuracy and reproducibility and does not make direct physical contact with the fluid in the pipe. Low fabrication costs and fast response make ultrasonic flowmeters widely used for two-phase flow measurements in both horizontal and vertical orientations. The void fraction or liquid holdup and velocity are the two most essential parameters for flow monitoring. The Time of Flight (ToF) method is mainly used for measurements in several ultrasonic flowmeter methods. In the present manuscript, the introductory section of this review explains the advantages of using the Time of Flight (ToF) method and its basic principles. This review also discusses research on measuring velocity and flow rate, differences in intrusive and non-intrusive measurement methods, parameters that affect ultrasonic measurements, and finally, measuring film thickness using non-intrusive methods.

Howling shadows: First report of domestic dog attacks on globally threatened mountain tapirs in high Andean cloud forests of Colombia

Domestic dogs (Canis lupus familiaris) are recognised worldwide not only as man’s best friend, but also as a form of anthropogenic edge effect impacting wildlife through predation, competition and disease infection. In the Northern Andes, there is growing evidence of dogs inducing activity shifts or alterations in the habitat use of native mammalian species. However, little information exists on direct attacks of dogs on wildlife, even in the case of species of conservation concern such as the mountain tapir (Tapirus pinchaque). Here, we used camera traps to report two cases of dogs chasing and attacking mountain tapirs in a protected area of the Central Andes of Colombia. The first event showed a direct physical contact between a living adult mountain tapir and two dogs, but the picture’s angle did not lead to observable signs of wounds or other injuries. The second event showed an adult mountain tapir running while being chased by the same two dogs of the first event, denoting a stressful moment for the tapir. This may have negative consequences on the populations of mountain tapirs through decreased reproductive performance and foraging efficiency, increased potential for disease outbreaks and more. Population management and control of domestic dogs inside and around protected areas must be considered a priority in future conservation actions to support a healthy population of mountain tapirs and other imperilled species in the region.

THE IMPACT OF CONTACTLESS PAYMENT CARDS ON CUSTOMER SATISFACTION: THE CASE OF LEBANON

Paying using a contactless card is the latest payment technology. There is an urgent need to study the cultural trend towards alternative payment methods in light of these financial incentives. The contactless card system is a practical replacement for cash in low-value transactions due to its ability to compete with cash. Non-cash payments are represented by contactless payment systems that do not require direct physical contact between the consumer's payment device and the merchant's POS terminal. As a result, contactless payment is seen as a more viable alternative to cash than standard payment cards. Therefore, central banks in charge of currency distribution have a vested interest in debating the future of cash use. The researcher uses convenience sampling since they have access to the population. Many employees filled out the survey used in this research. There were 110 people requested to participate in the poll, but only 150 turned up. It is possible to have happiness after utilizing technology. Research shows that inherent attributes such as joy significantly affect how customers feel about new technology. It is generally known that consumers' hedonic motives affect their propensity to use online banking. It is hypothesized that intrinsic motivation influences the integrity and competence components of e-two trust. Customers who have had a positive experience with online banking are more likely to use it themselves because they see it the same way as others who have had a similar experience.

Examining Illusory Touch Perception in Virtual Reality among Virtual Reality Users

The phenomenon of illusory touch perception in virtual reality (VR) is a subject of increasing intrigue within online VR communities, where users report experiencing tactile sensations in the absence of direct physical contact, triggered solely by visual stimuli. This paper presents an exploratory study aimed at understanding the underlying mechanisms that contribute to the development of such illusory touch perceptions in immersive virtual environments. Through an online survey targeting VR users, this study collected qualitative data on the nature and frequency of these experiences. The survey was complemented by a review of existing literature on touch perception and multisensory integration, providing a foundational understanding of how sensory information is processed and perceived. The findings suggest that certain visual cues in VR can evoke tactile sensations, a phenomenon that may be enhanced by the immersive quality of the virtual environment and the user's previous sensory experiences and expectations. This paper discusses potential contributors to the phenomenon, such as the realism of the virtual environment, the user's level of immersion and presence, and the congruence of multisensory stimuli. Although this study sheds light on the conditions that may facilitate illusory touch perception in VR, the complexity of human sensory processing necessitates further research. Controlled experimental studies are required to establish a causal relationship between specific factors and the experience of illusory touch in VR, which could have significant implications for the fields of virtual reality and sensory augmentation technology.

A Gradient Stiffness-Programmed Circuit Board by Spatially Controlled Phase-Transition of Supercooled Hydrogel for Stretchable Electronics Integration.

Due to emerging demands in soft electronics, there is an increasing need for material architectures that support robust interfacing between soft substrates, stretchable electrical interconnects, and embedded rigid microelectronics chips. Though researchers have adopted rigid-island structures to solve the issue, this approach merely shifts stress concentrations from chip-conductor interfaces to rigid-island-soft region interfaces in the substrate. Here, a gradient stiffness-programmed circuit board (GS-PCB) that possesses high stretchability and stability with surface mounted chips is introduced. The board comprises a stiffness-programmed hydrogel substrate and a laser-patterned liquid metal conductor. The hydrogel simultaneously obtains a large stiffness disparity and robust interfaces between rigid-islands and soft regions. These seemingly contradictory conditions are accomplished by adopting a gradient stiffness structure at the interfaces, enabled by combining polymers with different interaction energies and a supercooled sodium acetate solution. By integrating the gel with laser-patterned liquid metal with exceptional properties, GS-PCB exhibits higher electromechanical stability than other rigid-island research. To highlight the practicality of this approach, a finger-sensor device that successfully distinguishes objects by direct physical contact is fabricated, demonstrating its stability under various mechanical disturbances.