Nature inspired wet adhesive E-Skin patch for biosensing applications

Tree frogs are able to climb or stick to wet and rough surfaces. The hexagonal epithelial cells enclosed by profound passages which shield the surface of each toe pad and the array of nano-pillars on their surface are the main reason for their outstanding reversible adhesion in wet and rough environment. Inspired by the frog toe pad hexagonal hierarchical micro-pillars are developed by using Silicon rubber/ZrO2 nanocomposite. Due to the addition of oxide nanoparticles wettability properties of the rubber enhanced. The interlocking structures and hexagonal pattern helps to improve the capillary action and the sweat/water particles are drained easily, as a result surface adhesion increases. To design the hexagonal micro-pillars innovative laser engraving technique is adopted. The homogeneous distribution of nanoparticles and hierarchical hexagonal micro-patterns are confirmed through SEM analysis. This innovative design approach is helpful to design E-skin adhesive wearable devices for accurate monitoring of physiological signals.This work is supported by National Funds through the Portuguese Science Foundation (FCT) within project “FCT Reference No.: 030353 of IC&DT - AAC No. 02 / SAICT / 2017”, co-financed by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalization (COMPETE 2020), under Portugal 2020. Finally, this work was supported by FCT national funds, under the national support to R&D units grant, through the reference projects UIDB/04436/2020 and UIDP/04436/2020

Design and development of Ca-Mg-Fe-Ti-oxides based perovskite for high sensitive humidity sensors and wound healing applications / Ashis Tripathy

Armalcolite, which is a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Fe-Ti based oxides (CMFTO), their chemical reactions, and bonding with polydimethylsiloxane (PDMS) were determined by x-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMFTO was high. Different types of humidity sensors were developed using three distinct principles. The lower dielectric loss tangent value was obtained for the CMFTO ceramic sintered at 1050 °C (S1050) (0.155 at 1 MHz) and S1050/PDMS nanocomposite (0.002 at 1 MHz) film, which was made by spin coating at 3000 rpm. The excellent flexibility (Young’s modulus≈0.27 MPa and elongation >90%), viscoelastic property (tan = E″/E′: 0.225) and glass transition temperature (Tg: -58.5 °C) were obtained for S1050/PDMS film. Humidity dependent capacitive, resistive, and dielectric response of S1050 electroceramic was studied successfully. The S1050 electroceramic based capacitive sensor showed excellent sensitivity of 3000% as well as fast response (14.5 s) and recovery (34.27 s) times, which are extremely lower than those of the other conventional capacitive humidity sensors. The impedance and dielectric sensors showed improved sensitivity of 0.23 MΩ/Δ%RH and ~2310%, respectively. The response and recovery times were 20 and 40 s, respectively for resistive sensor and for dielectric sensor, they were 18 and 35 s, respectively. All the three capacitive, resistive and dielectric humidity sensors showed extreamly low hysteresis and high stability. Therefore, best sensing performance of the flexible S1050/PDMS composite film (306%) based humidity sensor was found at 100 Hz, better than conventional materials. In order to evaluate the biocompability of the S1050 and S1050/PDMS composite film based sensors with the direct contact to dermal surface, an in vitro study was employed using human dermis fibroblast cells. It showed that both the materials have good biocompatibility and can thus be suitable for measuing the humidity at the skin and inner prosthetic surfaces. To evaluate the drug carrying capacity of the present nanomaterials with the direct contact to dermal surface for wound healing applications, an in vivo assay was performed by aplying some hydrogels on rat’s dorsal wounds. To investigate the histological and immunohistochemical effects of the curcumin drug loaded S1050 nanocomposite hydrogels disperred in poly(vinyl alcohol) solution, an in vivo cutaneous full-thickness excisional wound rat model was adopted using adult male sprague dawley (SD) rats. The normal and diabetic (created by injection of Streptozotocin (dosage: 55mg/kg)) rats were wounded of size 2 cm diameter at the posterior neck area. The rats were topically applied with 0.2 ml gels of curcumin, S1050, and curcumin loaded S1050 hydrogel separately for 14 days. Many interesting improved results were found for diabetic subjects using present hydrogels. Briefly, the in vivo results revealed improved wound contraction and tissue regeneration in diabetic rats applied with curcumin, S1050, and curcumin loaded S1050 hydrogels as compared with diabetic rats using normal hydrogel. Moreover, beside sensors, the novel S1050 (i.e. armalcolite based nanocomposites) would be potential drug carrier for wound healing applications since their hydrogels showed as biocompatible, nontoxic, nonimmunogenic, and efficient drug carriers

A nature-inspired superhydrophilic nano-powder based silicone rubber composite

Silicone-Rubber (SR) is an elastomer prominently used in biomedical and medical devices, implants, and winter shoe industries because of its stability, durability, friction properties, biocompatibility, anti-bacterial, temperature resistance, and hypoallergenic characteristics. However, inherent hydrophobicity limits the use of SR as it cannot form a protective liquid layer for implants and medical devices while placed internally or externally and impairs tissue adhesion as well. Moreover, hydrophobicity reduces ice adhesion strength in the absence of capillary bridges and that makes winter shoe-soles more slippery. The physical and chemical solutions like oxidation, UV, plasma, corona discharge, gamma radiation, and Laser radiation grafting to turn SR into hydrophilic are either temporary or change the bulk properties of the compounds. We propose an innovative multifunctional SR composite incorporating zirconia and/or titania nanoparticles produced by roller mixing followed by hot compression moulding (pressure/heating vulcanisation). Subsequently, nature-inspired patterns like gecko or frog toepads are produced on SR compound by Laser-Surface-Texturing (LST) to expose the nanoparticles that attract water molecules. A parametric optimisation along with nano-powder percentage decides the wettability of the composite. A permanent superhydrophilic SR compound was produced that can be further used to increase ice adhesion to manufacture anti-slipping winter shoe-soles or other biomedical applications.This work was supported by Foundation for Science and Technology (FCT) national funds, under the national support to R&D units grant. The work is supported by the project “BioInSole-Multi-Functional Bioinspired Slip Resistant Shoe-Sole” under the reference UIDP/04436/2020 and Association for Innovation and Development from FCT (Caparica) (PTDC/EME-EME/7860/2O20). Vipin Richhariya also acknowledges FCT for his individual PhD scholarship through “Design and development of multifunctional surfaces to control friction behaviour in the presence of water” under the reference UI/BD/150939/2021

Congenital chylous ascites treated successfully with MCT-Based formula and octreotide

Medium chain triglyceride (MCT)-based diet, total parenteral nutrition (TPN) and repeated paracentesis are considered as supportive management for congenital chylous ascites (CCA). TPN is considered where therapy with oral MCT is poorly tolerated by the patient especially young infant with unstable hemodynamic. Surgery is recommended when medical therapy fails. Herein, we report a 2΍-month-old infant with CCA, treated successfully with octreotide intravenous infusion after the initial failure to response to conventional conservative therapy with MCT-enriched formula and paracentesis

A Bio-inspired anti-slipping winter shoe-sole

Hundreds of thousands of people injure every year due to Slips and Falls (SF) around the globe. The SF on ice during wintertime is an inevitable proposition. Though SF injuries don’t seem concerning, it ranks second among the causes of injuries in the world claiming billions of euros and thousands of lives. The staggering outcomes of SF are loss of jobs (for the people getting injured), loss of skilled workers (for the companies which trained the worker), expenses on the healthcare, burden on the insurance companies and social securities. To reduce SF, anti-slipping shoe-soles are used, however, existing soles provide very limited rescue from the slippage. Moreover, existing solution either modify material or tread design to increase friction on the icy surfaces. In this work, nature-inspired anti-slipping winter shoe-soles are being explored that combine material and tread design variation together using Laser Surface Texturing (LST) to obtain higher friction.This work was supported by FCT national funds, under the national support to R&D units grant, through the reference projects UIDB/04436/2020 and UIDP/04436/2020. We also acknowledge the project “BioInSole-Multi-Functional Bioinspired Slip Resistant Shoe-Sole” Associação para a Inovação e Desenvolvimento da FCT (Caparica) (PTDC/EME-EME/7860/2O20) and Vipin Richhariya acknowledges FCT for his PhD scholarship through “Projeto e Desenvolvimento de Superfícies Multifuncionais para Controlo do Comportamento à Fricção na Presença de Água (UI/BD/150939/2021)

Role of Morphological Structure, Doping, and Coating of Different Materials in the Sensing Characteristics of Humidity Sensors

The humidity sensing characteristics of different sensing materials are important properties in order to monitor different products or events in a wide range of industrial sectors, research and development laboratories as well as daily life. The primary aim of this study is to compare the sensing characteristics, including impedance or resistance, capacitance, hysteresis, recovery and response times, and stability with respect to relative humidity, frequency, and temperature, of different materials. Various materials, including ceramics, semiconductors, and polymers, used for sensing relative humidity have been reviewed. Correlations of the different electrical characteristics of different doped sensor materials as the most unique feature of a material have been noted. The electrical properties of different sensor materials are found to change significantly with the morphological changes, doping concentration of different materials and film thickness of the substrate. Various applications and scopes are pointed out in the review article. We extensively reviewed almost all main kinds of relative humidity sensors and how their electrical characteristics vary with different doping concentrations, film thickness and basic sensing materials. Based on statistical tests, the zinc oxide-based sensing material is best for humidity sensor design since it shows extremely low hysteresis loss, minimum response and recovery times and excellent stability

Anti-slipping winter shoe-soles: a nature-inspired solution

Apresentação efetuada em "Junior Euromat 2022", em Coimbra, 2022This work was supported by FCT national funds, under the national support to R&D units grant, through the reference projects UIDB/04436/2020 and UIDP/04436/2020, “BioInSole-Multi-Functional Bioinspired Slip Resistant Shoe-Sole” Associação para a Inovação e Desenvolvimento da FCT (Caparica) (PTDC/EME-EME/7860/2020) , and Vipin Richhariya acknowledges FCT for his PhD scholarship through “Projeto e Desenvolvimento de Superfícies Multifuncionais para Controlo do Comportamento à Fricção na Presença de Água (UI/BD/150939/2021)”

Moisture sensitive inimitable Armalcolite/PDMS flexible sensor: A new entry

Armalcolite, a pioneering material which is commonly available on the moon surface, was synthesized first time in the laboratory environment using innovative solid-state-step sintering process. Afterwards, Armalcolite/Polydimethylsiloxane (PDMS) nanocomposite was prepared using ball milling technique and then spin coated on interdigitated customized gold (Au) electrode on a polyimide substrate in order to develop a high sensitive and fast-response flexible humidity sensor. To evaluate the performance of developed flexible humidity sensor, the electrical characterization was performed at room temperature of 25 °C in a humidity environment of 33–95% RH using alternating current. The developed sensor exhibits an exceptional performance in terms of high sensitivity, good linearity, negligible hysteresis (<1%), better response and recovery time of 10 s and 15 s respectively, which is outstanding when compared with existing ones within the same category. The long-term stability of flexible sensor was confirmed upon when it was put into test for 30 consecutive days. Due to its grater flexibility, low hysteresis, high stability and the fast response/recovery time, it is intended to use for various application in modern industry, agriculture, and medical care where humidity plays a crucial role

Dielectric and AC conductivity studies of novel porous armalcolite nanocomposite-based humidity sensor

Armalcolite, a current motivated rare earth ceramic usually available in the moon, had been used for the first time, as dielectric-type humidity sensors. The armalcolite nanocomposite was prepared using multistep solid-state sintering under high pressure and a high-sensitive dielectric sensor was developed for humidity controlling applications. Different concerning phases developed by the proper sintering were analyzed precisely by X-ray diffraction (XRD) as well as scanning electron microscopy (SEM). At 100 Hz frequency, the obtained dielectric constant was 24 times greater at 95% relative humidity (RH) as compared to 33% RH. The armalcolite-based sensor showed lower hysteresis (<3.5%), good stability, and faster response (~18 seconds) and recovery (~35 seconds) times compared to conventional humidity sensors. The sensing mechanism of the nanocomposite was categorically determined by the analyzed characteristics parameters such as dielectric constants, normalized loss tangent, and alternating current conductivity properties. This study also confirmed that the whole conduction mechanism was accomplished by electrons or ions and dipoles in the entire RH range. Therefore, the present armalcolite-based porous nanocomposite would be a potential sensing material for novel humidity sensors