New spin coated multilayer lactate biosensor for acidosis monitoring in continuous flow assisted with an electrochemical pH probe.

A LOx-based electrochemical biosensor for high-level lactate determination was developed. For the construction of the biosensor, chitosan and Nafion layers were integrated by using a spin coating procedure, leading to less porous surfaces in comparison with those recorded after a drop casting procedure. The analytical performance of the resulting biosensor for lactate determination was evaluated in batch and flow regime, displaying satisfactory results in both modes ranging from 0.5 to 20 mM concentration range for assessing the lactic acidosis. Finally, the lactate levels in raw serum samples were estimated using the biosensor developed and verified with a blood gas analyzer. Based on these results, the biosensor developed is promising for its use in healthcare environment, after its proper miniaturization. A pH probe based on common polyaniline-based electrochemical sensor was also developed to assist the biosensor for the lactic acidosis monitoring, leading to excellent results in stock solutions ranging from 6.0 to 8.0 mM and raw plasma samples. The results were confirmed by using two different approaches, blood gas analyzer and pH-meter. Consequently, the lactic acidosis monitoring could be achieved in continuous flow regime using both (bio)sensors.

Preparation of CoFe@C composite modified electrode for neohesperidin dihydrochalcone sensing and its application in Chinese medicine.

CoFe@C was first prepared by calcining the precursor of CoFe-metal-organic framework-74 (CoFe-MOF-74), then an electrochemical sensor for the determination of neohesperidin dihydrochalcone (NHDC) was constructed, which was stemmed from the novel CoFe@C/Nafion composite film modified glassy carbon electrode (GCE). The CoFe@C/Nafion composite was verified by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) was used to evaluate its electrical properties as a modified material for an electrochemical sensor. Compared with CoFe-MOF-74 precursor modified electrode, CoFe@C/Nafion electrode exhibited a great synergic catalytic effect and extremely increased the oxidation peak signal of NHDC. The effects of various experimental conditions on the oxidation of NHDC were investigated and the calibration plot was tested. The results bespoken that CoFe@C/Nafion GCE has good reproducibility and anti-interference under the optimal experimental conditions. In addition, the differential pulse current response of NHDC was linear with its concentration within the range 0.08 ~ 20 µmol/L, and the linear regression coefficient was 0.9957. The detection limit was as low as 14.2 nmol/L (S/N = 3). In order to further verify the feasibility of the method, it was successfully used to determine the content of NHDC in Chinese medicine, with a satisfactory result, good in accordance with that of high performance liquid chromatography (HPLC).

Anodic stripping voltammetry of arsenic determination with edible mushroom-nafion-modified glassy carbon electrode.

An edible Mushroom-Nafion modified glassy carbon electrode (M2N5-GCE) was prepared using a homogeneous mixture varying the concentrations of these, in addition to the origin of the mushroom (Shiitake, Lentinula edodes, M1 and Abrantes, Agariscus bisporus, M2) and applied to the As(III) determination by anodic stripping voltammetry. After choosing the optimal conditions in the preparation of the electrode, the second stage was to study the effects of various parameters such as supporting electrolyte, pH, accumulation potential, and time (Eacc, tacc). The optimum experimental conditions chosen were Britton Robinson buffer 0.01 mol L-1 pH:4.6; Eacc: -1.0 and tacc: 60 s obtaining a signal of oxidation of As(0) to As(III) about 0.08 V. Peak current was proportional to arsenic concentration over the 19.6-117.6 µg L-1 range, with a 3σ detection limit of 13.4 µg L-1. The method was validated using As(III) spiked tap water from the laboratory with satisfactory results (RE:3.0 %). Finally, the method was applied to the determination of As(III) in water samples from the Loa River (Northern Chile) in the presence of As(V) in a concentration >20 times higher (RE: 2.3 %).

PVDF-HFP encapsulated WS2nanosheets in droplet-based triboelectric nanogenerators for possible detection of human Na+/K+ion concentration.

Here we report the liquid-solid interaction in droplet-based triboelectric nanogenerators (TENG) for estimation of human Na+/K+levels. The exploitation of PVDF-HFP encapsulated WS2as active layer in the droplet-based TENG (DTENG) leads to the generation of electrical signal during the impact of water droplet. Comparison over the control devices indicates that surface quality and dielectric nature of the PVDF-HFP/WS2composite largely dictates the performance of the DTENG. The demonstration of excellent sensitivity of the DTENG towards water quality indicates its promising application towards water testing. In addition, the alteration in output signal with slightest variation in ionic concentration (Na+or K+) in water has been witnessed and is interpreted with charge transfer and ion transfer processes during liquid-solid interaction. The study reveals that the ion mobility largely affects the ion adsorption process on the active layer of PVDF-HFP/WS2and thus generates distinct output profiles for diverse ions like Na+and K+. Following that, the DTENG characteristics have been exploited to artificial urine where the varying output signals have been recorded for variation in urinary Na+ion concentration. Therefore, the deployment of PVDF-HFP/WS2in DTENG holds promising application towards the analyse of ionic characteristics of body fluids.

Label-free electrochemical biosensor based on green-synthesized reduced graphene oxide/Fe3O4/nafion/polyaniline for ultrasensitive detection of SKBR3 cell line of HER2 breast cancer biomarker.

Cancer stands as one of the most impactful illnesses in the modern world, primarily owing to its lethal consequences. The fundamental concern in this context likely stems from delayed diagnoses in patients. Hence, detecting various forms of cancer is imperative. A formidable challenge in cancer research has been the diagnosis and treatment of this disease. Early cancer diagnosis is crucial, as it significantly influences subsequent therapeutic steps. Despite substantial scientific efforts, accurately and swiftly diagnosing cancer remains a formidable challenge. It is well known that the field of cancer diagnosis has effectively included electrochemical approaches. Combining the remarkable selectivity of biosensing components-such as aptamers, antibodies, or nucleic acids-with electrochemical sensor systems has shown positive outcomes. In this study, we adapt a novel electrochemical biosensor for cancer detection. This biosensor, based on a glassy carbon electrode, incorporates a nanocomposite of reduced graphene oxide/Fe3O4/Nafion/polyaniline. We elucidated the modification process using SEM, TEM, FTIR, RAMAN, VSM, and electrochemical methods. To optimize the experimental conditions and monitor the immobilization processes, electrochemical techniques such as CV, EIS, and SWV were employed. The calibration graph has a linear range of 102-106 cells mL-1, with a detection limit of 5 cells mL-1.

A novel potentiometric screen-printed electrode based on crown ethers/nano manganese oxide/Nafion composite for trace level determination of copper ion in biological fluids.

Copper levels in biological fluids are associated with Wilson's, Alzheimer's, Menke's, and Parkinson's diseases, making them good biochemical markers for these diseases. This study introduces a miniaturized screen-printed electrode (SPE) for the potentiometric determination of copper(II) in some biological fluids. Manganese(III) oxide nanoparticles (Mn2O3-NPs), dispersed in Nafion, are drop-casted onto a graphite/PET substrate, serving as the ion-to-electron transducer material. The solid-contact material is then covered by a selective polyvinyl chloride (PVC) membrane incorporated with 18-crown-6 as a neutral ion carrier for the selective determination of copper(II) ions. The proposed electrode exhibits a Nernstian response with a slope of 30.2 ± 0.3 mV/decade (R2 = 0.999) over the linear concentration range 5.2 × 10-9 - 6.2 × 10-3 mol/l and a detection limit of 1.1 × 10-9 mol/l (69.9 ng/l). Short-term potential stability is evaluated using constant current chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). A significant improvement in the electrode capacitance (91.5 µF) is displayed due to the use of Mn2O3-NPs as a solid contact. The presence of Nafion, with its high hydrophobicity properties, eliminates the formation of the thin water layer, facilitating the ion-to-electron transduction between the sensing membrane and the conducting substrate. Additionally, it enhances the adhesion of the polymeric sensing membrane to the solid-contact material, preventing membrane delamination and increasing the electrode's lifespan. The high selectivity, sensitivity, and potential stability of the proposed miniaturized electrode suggests its use for the determination of copper(II) ions in human blood serum and milk samples. The results obtained agree fairly well with data obtained by flameless atomic absorption spectrometry.

Chloroperfluoropolyether carboxylate compounds: A review.

Several new per- and polyfluoroalkyl substances (PFASs) have been synthesized to replace traditional (legacy) PFASs frequently without clear information on their structure, use and potential toxicity. Among them, chloroperfluoropolyether carboxylates (ClPFPECAs) are an emerging group used as processing aids in the production of fluoropolymers to replace the ammonium salt of perfluorononanoic acid (PFNA). The Solvay Company has produced ClPFPECAs as a mixture of six congeners (oligomers) since the mid-1990s, but other possible manufacturers and annual quantities synthesized and used worldwide are unknown. Initial studies to monitor their presence were conducted because of public authority concerns about suspect environmental contamination near fluoropolymer plants. As of 2015, these chemicals have been found in soil, water, vegetative tissues and wildlife, as well as in biological fluids of exposed workers and people, in research carried out mainly in the United States (New Jersey) and Italy. Analysis of wildlife collected even in non-industrialized areas demonstrated widespread occurrence of ClPFPECAs. From the analytical point of view, the (presumptive) evidence of their presence was obtained through the application of non-targeted approaches performed by liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS). Available toxicological data show that ClPFPECAs have similar adverse effects than the compounds which they have replaced, whereas their carcinogenic potential and reproductive damage are currently unknown. All these observations once again cast doubt on whether many alternatives to traditional PFAS are actually safer for the environment and health.

Miniaturized Capsule System Toward Real-Time Electrochemical Detection of H2 S in the Gastrointestinal Tract.

Hydrogen sulfide (H2 S) is a gaseous inflammatory mediator and important signaling molecule for maintaining gastrointestinal (GI) homeostasis. Excess intraluminal H2 S in the GI tract has been implicated in inflammatory bowel disease and neurodegenerative disorders; however, the role of H2 S in disease pathogenesis and progression is unclear. Herein, an electrochemical gas-sensing ingestible capsule is developed to enable real-time, wireless amperometric measurement of H2 S in GI conditions. A gold (Au) three-electrode sensor is modified with a Nafion solid-polymer electrolyte (Nafion-Au) to enhance selectivity toward H2 S in humid environments. The Nafion-Au sensor-integrated capsule shows a linear current response in H2 S concentration ranging from 0.21 to 4.5 ppm (R2 = 0.954) with a normalized sensitivity of 12.4% ppm-1 when evaluated in a benchtop setting. The sensor proves highly selective toward H2 S in the presence of known interferent gases, such as hydrogen (H2 ), with a selectivity ratio of H2 S:H2 = 1340, as well as toward methane (CH4 ) and carbon dioxide (CO2 ). The packaged capsule demonstrates reliable wireless communication through abdominal tissue analogues, comparable to GI dielectric properties. Also, an assessment of sensor drift and threshold-based notification is investigated, showing potential for in vivo application. Thus, the developed H2 S capsule platform provides an analytical tool to uncover the complex biology-modulating effects of intraluminal H2 S.

Non-extractable PFAS in functional textiles - characterization by complementary methods: oxidation, hydrolysis, and fluorine sum parameters.

Per- and polyfluoroalkyl substances (PFAS) are widely used for durable water-repellent finishing of different fabrics and textiles such as outdoor clothing, carpets, medical textiles and more. Existing PFAS extraction techniques followed by target analysis are often insufficient for detecting widely used side-chain fluorinated polymers (SFPs) that are barely or non-extractable. SFPs are typically copolymers consisting of a non-fluorinated backbone with perfluoroalkyl side-chains to obtain desired properties. We compared the accessible analytical information and performance of complementary techniques based on oxidation (dTOP and PhotoTOP assays), hydrolysis (THP assay), standard extraction, extractable organic fluorine (EOF), and total fluorine (TF) with five functional textiles and characterized 7 further textiles only by PhotoTOP oxidation. The results show that when applied directly to textile samples, dTOP and PhotoTOP oxidation and also hydrolysis (THP) are able to capture large fractions of TF in the form of perfluoroalkyl side-chains present in the textiles while methods relying on extracts (EOF, target and non-target analysis) yield much lower fractions of TF (e.g., factor ∼25-50 lower). The conversion of large fractions of the measured TF into PFCAs or FTOHs from fluorinated side chains is in contrast to previous studies. Concentrations ranged from

Fate of Per- and Polyfluoroalkyl Substances from Durable Water-Repellent Clothing during Use.

To make outdoor clothing water- or dirt-repellent, durable water-repellent (DWR) coatings based on side-chain fluorinated polymers (SFPs) are used. During use of outdoor clothing, per- and polyfluoroalkyl substances (PFASs) can be emitted from the DWR to the environment. In this study, the effects of aging, washing, and tumble drying on the concentration of extractable PFASs in the DWR of perfluorohexane-based short-chain SFPs (FC-6 chemistry) and of perfluorooctane-based long-chain SFPs (FC-8 chemistry) were assessed. For this purpose, polyamide (PA) and polyester (PES) fabrics were coated with FC-6- and FC-8-based DWRs. Results show that aging of the coated fabrics causes an increase in concentration and formation of perfluoroalkyl acids (PFAAs). The effect of aging on the volatile PFASs depends on the type of fabric. Washing causes a decrease in PFAA concentrations, and in general, volatile PFASs are partly washed out of the textiles. However, washing can also increase the extractable concentration of volatile PFASs in the fabrics. This effect becomes stronger by a combination of aging and washing. Tumble drying does not affect the PFAS concentrations in textiles. In conclusion, aging and washing of fabrics coated with the DWR based on SFPs release PFASs to the environment.

Enhanced proton conductivity of Nafion membrane induced by incorporation of MOF-anchored 3D microspheres: a superior and promising membrane for fuel cell applications.

A novel 3D core-shell material composed of polyacrylate carboxyl microspheres (PCMs) and ZIF-8 nanoparticles was used to promote proton conduction in the Nafion matrix. The Nafion/ZIF-8@PCM membranes displayed excellent proton conductivity (0.24 S cm-1) and physicochemical properties due to special structural characteristics. More importantly, this new concept has a strong practical guiding significance for the fabrication of novel PEMs.

Per- and polyfluoroalkyl substances in the environment.

Over the past several years, the term PFAS (per- and polyfluoroalkyl substances) has grown to be emblematic of environmental contamination, garnering public, scientific, and regulatory concern. PFAS are synthesized by two processes, direct fluorination (e.g., electrochemical fluorination) and oligomerization (e.g., fluorotelomerization). More than a megatonne of PFAS is produced yearly, and thousands of PFAS wind up in end-use products. Atmospheric and aqueous fugitive releases during manufacturing, use, and disposal have resulted in the global distribution of these compounds. Volatile PFAS facilitate long-range transport, commonly followed by complex transformation schemes to recalcitrant terminal PFAS, which do not degrade under environmental conditions and thus migrate through the environment and accumulate in biota through multiple pathways. Efforts to remediate PFAS-contaminated matrices still are in their infancy, with much current research targeting drinking water.

Transvaginal repair of anterior vaginal wall prolapse with polyvinylidene fluoride (PVDF) mesh: an alternative for previously restricted materials?

INTRODUCTION AND HYPOTHESIS: To study the mid-term safety and functional outcomes of transvaginal anterior vaginal wall prolapse repair using polyvinylidene fluoride (PVDF) mesh (DynaMesh®-PR4) by the double trans-obturator technique (TOT). METHODS: Between 2015 and 2020, we prospectively included women with symptomatic high-stage anterior vaginal wall prolapse with or without uterine prolapse or stress urinary incontinence (SUI) in the study. The patients underwent transvaginal repair of the prolapse using PVDF mesh in two medical centers. We followed all patients for at least 12 months. We recorded the characteristics of vaginal and sexual symptoms, urinary incontinence, and prolapse stage pre- and postoperatively using International Consultation on Incontinence Questionnaire-Vaginal Symptoms (ICIQ-VS), International Consultation on Incontinence Questionnaire-Urinary Incontinence-Short Form (ICIQ-UI-SF), and Pelvic Organ Prolapse Quantification (POP-Q) system, respectively. RESULTS: One hundred eight women were included in the final analysis with a mean follow-up time of 34.5 ± 18.6 months. The anatomical success was achieved in 103 (95.4%) patients. There was a significant improvement in patients' vaginal symptoms, urinary incontinence, and quality of life scores postoperatively (p < 0.0001). Only six patients (5.5%) had mesh extrusion, five of whom were managed successfully. The total rates of complications and de novo urinary symptoms were 21.3% and 7.4%, respectively. Significant pain was reported in 17 cases (15.7%). CONCLUSION: Our findings show that using PVDF mesh in the double TOT technique for anterior vaginal wall prolapse repair is a safe procedure with high anatomic and functional success rates and acceptable complication rates in mid-term follow-up.

PVDF and P(VDF-TrFE) Electrospun Scaffolds for Nerve Graft Engineering: A Comparative Study on Piezoelectric and Structural Properties, and In Vitro Biocompatibility.

Polyvinylidene fluoride (PVDF) and its copolymer with trifluoroethylene (P(VDF-TrFE)) are considered as promising biomaterials for supporting nerve regeneration because of their proven biocompatibility and piezoelectric properties that could stimulate cell ingrowth due to their electrical activity upon mechanical deformation. For the first time, this study reports on the comparative analysis of PVDF and P(VDF-TrFE) electrospun scaffolds in terms of structural and piezoelectric properties as well as their in vitro performance. A dynamic impact test machine was developed, validated, and utilised, to evaluate the generation of an electrical voltage upon the application of an impact load (varying load magnitude and frequency) onto the electrospun PVDF (15-20 wt%) and P(VDF-TrFE) (10-20 wt%) scaffolds. The cytotoxicity and in vitro performance of the scaffolds was evaluated with neonatal rat (nrSCs) and adult human Schwann cells (ahSCs). The neurite outgrowth behaviour from sensory rat dorsal root ganglion neurons cultured on the scaffolds was analysed qualitatively. The results showed (i) a significant increase of the ß-phase content in the PVDF after electrospinning as well as a zeta potential similar to P(VDF-TrFE), (ii) a non-constant behaviour of the longitudinal piezoelectric strain constant d33, depending on the load and the load frequency, and (iii) biocompatibility with cultured Schwann cells and guiding properties for sensory neurite outgrowth. In summary, the electrospun PVDF-based scaffolds, representing piezoelectric activity, can be considered as promising materials for the development of artificial nerve conduits for the peripheral nerve injury repair.

Physiologically Self-Regulated, Fully Implantable, Battery-Free System for Peripheral Nerve Restoration.

The long-segment peripheral nerve injury (PNI) represents a global medical challenge, leading to incomplete nerve tissue recovery and unsatisfactory functional reconstruction. However, the current electrical stimulation (ES) apparatuses fail perfect nerve repair due to their inability of the variable synchronous self-regulated function with physiological states. It is urgent to develop an implantable ES platform with physiologically adaptive function to provide instantaneous and nerve-preferred ES. Here, a physiologically self-regulated electrical signal is generated by integrating a novel tribo/piezoelectric hybrid nanogenerator with a nanoporous nerve guide conduit to construct a fully implantable neural electrical stimulation (FI-NES) system. The optimal neural ES parameters completely originate from the body itself and are highly self-responsive to different physiological states. The morphological evaluation, representative protein expression level, and functional reconstruction of the regenerated nerves are conducted to assess the PNI recovery process. Evidence shows that the recovery effect of 15 mm length nerve defects under the guidance of the FI-NES system is significantly close to the autograft. The designed FI-NES system provides an effective method for long-term accelerating the recovery of PNI in vivo and is also appropriate for other tissue injury or neurodegenerative diseases.

Self-Powered Interactive Fiber Electronics with Visual-Digital Synergies.

Fiber electronics with mechanosensory functionality are highly desirable in healthcare, human-machine interfaces, and robotics. Most efforts are committed to optimize the electronically readable interface of fiber mechanoreceptor, while the user interface based on naked-eye readable output is rarely explored. Here, a scalable fiber electronics that can simultaneously visualize and digitize the mechanical stimulus without external power supply, named self-powered optoelectronic synergistic fiber sensors (SOEFSs), are reported. By coupling of space and surface charge polarization, a new mechanoluminescent (ML)-triboelectric synergistic effect is realized. It contributes to remarkable enhancement of both electrical (by 100%) and optical output (by 30%), as well as novel temporal-spatial resolution mode for motion capturing. Based on entirely new thermoplastic ML material system and spinning process, industrial-level continuously manufacture and recycling processes of SOEFS are realized. Furthermore, SOEFSs' application in human-machine interface, virtual reality, and underwater sensing, rescue, and information interaction is demonstrated.

Polyvinylidene fluoride/silk fibroin-based bio-piezoelectric nanofibrous scaffolds for biomedical application.

Since the discovery that applying electrical stimulation can promote cell growth, proliferation, and tissue regeneration, research on bio-piezoelectric materials is being actively conducted. In this study, a composite material was prepared by mixing polyvinylidene fluoride (PVDF), a conventional piezoelectric polymer, and silk fibroin (SF), a natural piezoelectric material that recently attracting attention. These two polymers were fabricated into a composite fiber mat using electrospinning technology. To find optimal conditions, SF was added in various ratios to prepare electrospun PVDF/SF mats. The characteristics of these PVDF/SF composite mats were then analyzed through various evaluations and in vitro studies. It was confirmed that PVDF and SF were successfully mixed through scanning electron microscope images and structural analysis such as x-ray diffractometer and Fourier transform infrared. The results revealed that adding an appropriate amount of SF could improve the tensile strength, enhance cell proliferation rate, and generate a voltage similar to that of a conventional PVDF-only electrospinning mat. Such fabricated electrospun PVDF/SF composite mats are expected to be useful in the bio-piezoelectric field because they can maintain piezoelectricity while compensating for the shortcomings, such as low physical properties, of a PVDF electrospun mat.

Antibacterial Filtration Membranes Based on PVDF-co-HFP Nanofibers with the Addition of Medium-Chain 1-Monoacylglycerols.

The efficiency of filtration membranes is substantially lowered by bacterial attachments and potential fouling processes, which reduce their durability and lifecycle. The antibacterial and antifouling properties exhibited by the added materials play a substantial role in their application. We tested a material poly(vinylidene fluoride)-co-hexafluoropropylene (PDVF-co-HFP) based on an electrospun copolymer, where an agent was incorporated with a small amount of ester of glycerol consecutively with caprylic, capric, and lauric acids. Each of these three materials differing in the esters (1-monoacylglycerol, 1-MAG) used was prepared with three weighted concentrations of 1-MAG (1, 2, and 3 wt %). The presence of 1-MAG with an amphiphilic structure resulted in the hydrophilic character of the prepared materials that contributed to the filtration performance. The tested materials (membranes) were characterized with rheological, optical (scanning electron microscopy, SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and other methods to evaluate antibacterial and antifouling activities. The pure water flux was 6 times higher than that of the neat PVDF-co-HFP membrane when the added 1-MAG attained only 1 wt %. It was experimentally shown that the PVDF-co-HFP/1-MAG membrane with high wettability improved antibacterial activity and antifouling ability. This membrane is highly promising for water treatment due to the safety of antibacterial 1-MAG additives.

Bioinspired Durable Antibacterial and Antifouling Coatings Based on Borneol Fluorinated Polymers: Demonstrating Direct Evidence of Antiadhesion.

Substituting natural products for traditional poison-killing antifouling agents is an efficient and promising method to alleviate the increasingly serious ecological crisis and aggravate the loss due to marine biofouling. Herein, the successful synthesis of poly(methyl methacrylate-co-ethyl acrylate-co-hexafluorobutyl methacrylate-co-isobornyl methacrylate) copolymer (PBAF) with borneol monomers and fluorine by a free radical polymerization method is reported. The PBA0.09F coating exhibits outstanding antibacterial and antifouling activity, achieving 98.2% and 92.3% resistance to Escherichia coli and Staphylococcus aureus, respectively, and the number of Halamphora sp. adhesion is only 26 (0.1645 mm2) in 24 h. This remarkable antibacterial and antifouling performance is attributed to the incorporation of fluorine components into the copolymer, which induces a low surface energy and hydrophobicity and the complex molecular structure of the natural nontoxic antifouling agent borneol. In addition, the results showed that the contents of the adhesion-related proteins mfp-3, mfp-5, and mfp-6 were significantly reduced, which proved that natural substances affect the secretion of biological proteins. Importantly, the PBAF coating exhibits excellent environmental friendliness and long-term stability. The antifouling mechanism is clarified, and an effective guide for an environmentally friendly antifouling coating design is proposed.

Wearable Electronics Based on the Gel Thermogalvanic Electrolyte for Self-Powered Human Health Monitoring.

There is always a temperature difference of more than 10 degrees between the human body, as a sustainable heat source, and the ambient temperature. Converting body heat into electricity that in turn is used to drive personal medical electronics is of significance in smart wearable medicine. To avoid the frangibility and complex preparation of traditional thermoelectric materials, we fabricated a gel electrolyte-based thermogalvanic generator with Fe3+/Fe2+ as a redox pair, which presents not only moderate thermoelectric performance but also excellent flexibility. With a micropore-widespread polyvinylidene fluoride diaphragm implanted in the gel, a thermal barrier was created between the two halves, effectively improving the Seebeck coefficient by reducing its thermal conductivity. Considering the superior temperature response of the gel, a self-powered body temperature monitoring system was established by conformally affixing it to the forehead. Meanwhile, the gel patch with a high specific heat capacity can effectively cool down fever patients. This work may offer a new train of thought for exploiting self-powered wearable medical electronics by scavenging low-grade body heat.