Flexible Triboelectric Nanogenerator for Promoting the Proliferation and Migration of Human Fibroblast Cells

Chronic wound healing is often a prolonged process with the migration and proliferation of fibroblast cells playing crucial roles. Electrical stimulation (ES) has emerged as a promising physical therapy modality to promote these key events. In this study, we address this issue by employing a triboelectric nanogenerator (TENG) as an electrical stimulator for both drug release and the stimulation of fibroblast cells. The flexible TENG with a sandwich structure was fabricated using a PCL nanofibrous layer, Kapton, and silicon rubber. The TENG could be folded to any degree and twisted, and it could return to its original shape when the force was removed. Cultured cells received ES twice and three times daily for 8 days, with a 30 min interval between sessions. By applying current in a safe range and appropriate time (twice daily), fibroblasts demonstrate an accelerated proliferation and migration rate. These observations were confirmed through cell staining. Additionally, in vitro tests demonstrated the TENG's ability to simultaneously provide ES and release vitamin C from the patch. After 2 h, the amount of released drug increased 2 times in comparison to the control group. These findings provide support for the development of a TENG for the treatment of wounds, which underlines the promise of this new technique for developing portable electric stimulation devices.

Self-powered triboelectric nanogenerator sensor for detecting humidity level and monitoring ethanol variation in a simulated exhalation environment

Respiration stands as a vital process reflecting physiological and pathological human health status. Exhaled breath analysis offers a facile, non-invasive, swift, and cost-effective approach for diagnosing and monitoring diseases by detecting concentration changes of specific biomarkers. In this study, we employed Polyethylene oxide/copper (I) oxide composite nanofibers (PCNFs), synthesized via the electrospinning method as the sensing material to measure ethanol levels (1-200 ppm) in an exhaled breath simulator environment. The integrated contact-separation triboelectric nanogenerator was utilized to power the self-powered PCNFs exhaled breath sensor. The PCNFs-based gas sensor demonstrates promising results with values of 0.9 and 3.2 for detecting 5 ppm and 200 ppm ethanol, respectively, in the presence of interfering gas at 90% relative humidity (RH). Notably, the sensor displayed remarkable ethanol selectivity, with ratios of 10:1 to methanol and 25:1 to acetone. Response and recovery times for 200 ppm ethanol at 90 RH% were rapid, at 2.7 s and 5.8 s, respectively. The PCNFs-based exhaled breath sensor demonstrated consistent and stable performance in practical conditions, showcasing its potential for integration into wearable devices. This self-powered breath sensor enabling continuous monitoring of lung cancer symptoms and facilitating compliance checks with legal alcohol consumption limits.

Enhanced proliferation and migration of fibroblast cells by skin-attachable and self-cleaning triboelectric nanogenerator

Skin wounds are common in accidental injuries, surgical operations, and chronic diseases. The migration and proliferation of fibroblast cells are fundamental to wound healing, which can be promoted by electrical stimulation as a physical therapy modality. Therefore, the development of portable electrical stimulation devices that can be used by patients on-site is an essential need. In the present study, a self-cleaning triboelectric nanogenerator (TENG) has been fabricated for enhancing cell proliferation and migration. The polycaprolactone‑titanium dioxide (PCL/TiO₂₎ and polydimethylsiloxane (PDMS) layers were fabricated via a facile method and used as the electropositive and electronegative pair, respectively. The effect of stimulation time on proliferation and migration of fibroblast cells was investigated. The results demonstrated that when the cells were stimulated once-a-day for 40 min, the cell viability was increased, while a long daily stimulation time has an inhibitory effect. Under electrical stimulation, the cells move toward the middle of the scratch, making the scratch almost invisible. During repeated movements, the prepared TENG connected to a rat skin generated an open-circuit voltage and a short-circuit current around 4 V and 0.2 μA, respectively. The proposed self-powered device can pave the way for a promising therapeutic strategy for patients with chronic wounds.

CNT-PDMS foams as self-powered humidity sensors based on triboelectric nanogenerators driven by finger tapping

An increasing number of frequently applied portable electronics has raised the significance of self-powered systems. In this regard, triboelectric nanogenerators (TENGs) have drawn considerable attention due to their diversity of design and high power output. As a widely used material in TENG electrodes, polydimethylsiloxane (PDMS) shows attractive characteristics, such as electron affinity, flexibility, and facile fabrication. To achieve active TENG-based humidity sensing, we proposed a straightforward method to enhance the hydrophilicity of PDMS by two parallel approaches: 1. Porosity induction, 2. Carbon nanotube (CNT) compositing. Both of the mentioned processes have been performed by water addition during the synthesis procedure, which is not only totally safe (in contrast with the similar foaming/compositing routes), but also applicable for a wide range of nanomaterials. Applying the modified electrode as a single-electrode TENG-based humidity sensor, demonstrated an impressive enhancement of sensing response from 56% up to 108%, compared to the bare electrodes. Moreover, the detecting range of ambient humidity was broadened to higher values of 80% in a linear behavior. The fabricated humidity sensor based on a CNT-PDMS foam not only provides superior sensing characteristics but also is satisfactory for portable applications, due to being lightweight and desirably self-powered.

Self-powered ultraviolet/visible photodetector based on graphene-oxide via triboelectric nanogenerators performing by finger tapping

Self-sufficient power sources provide a promising application of abundant electronic devices utilized in detection of ambient properties. Recently, triboelectric nanogenerators (TENGs) have been widely investigated to broaden the self-powered systems by converting the ambient mechanical agitations into electrical voltage and current. Graphene oxide (GO), not only for sensing applications but also as a brilliant energy-related nanomaterial, provides a wide range of controllable bandgap energies, as well as facile synthesis route. In this study, GO-based self-powered photodetectors have been fabricated by conflating the photosensitivity and triboelectric characteristics of freestanding GO paper. In this regard, photodetection via TENGs has been investigated in two forms of active and passive circuits for ultraviolet (UV) and visible illumination. The photodetector responsivity upon UV enhanced from 0.011 mA W^-1for conventional GO-photoresistors up to 13.41 mA W^-1by active photodetection setup. Moreover, applying the active-TENG improved the efficiency from 0.25% (in passive TENG) to 4.21%. Our findings demonstrate that active TENGs might enable materials with insignificant optical response to represent considerably higher light-sensitivity by means of synergizing the effect of TENG output changes with opto-electronical properties of desired layers.

A computational modelling study of excitation of neuronal cells with triboelectric nanogenerators

Neurological disorders and nerve injuries, such as spinal cord injury, stroke, and multiple sclerosis can result in the loss of muscle function. Electrical stimulation of the neuronal cells is the currently available clinical treatment in this regard. As an effective energy harvester, the triboelectric nanogenerators (TENG) can be used for self-powered neural/muscle stimulations because the output of the TENG provides stimulation pulses for nerves. In the present study, using a computational modelling approach, the effect of surface micropatterns on the electric field distribution, induced voltage and capacitance of the TENG structures have been investigated. By incorporating the effect of the TENG inside the mathematical model of neuron’s electrical behavior (cable equation with Hodgkin-Huxley model), its impact on the electrical behavior of the neurons has been studied. The results show that the TENG operates differently with various surface modifications. The performance of the TENG in excitation of neurons depends on the contact and release speed of its electrodes accordingly.

Nanostructured versus flat compact electrode for triboelectric nanogenerators at high humidity

The triboelectric nanogenerator (TENG) is a promising technology for mechanical energy harvesting. TENG has proven to be an excellent option for power generation but typically TENGs output power drops significantly in humid environments. In this work, the effect of electrode's material on power output, considering smooth and nanostructured porous structures with various surface hydrophobicity, is investigated under various humidity conditions. A vertical contact-separation mode TENG is experimentally and numerically studied for four surface morphologies of Ti foil, TiO2 thin film, TiO2 nanoparticulated film, and TiO2 nanotubular electrodes. The results show that the TENG electrical output in the flat structures such as Ti foil and TiO2 thin film at 50% RH is reduced to 50% of its initial state, while in the nanoporous structures such as nanoparticle and nanotube arrays, this is observed at RH above 95%. The results show that the use of porous nanostructures in TENG due to their high surface-to-volume, and that the process of water adsorption on the pore leads to better performance than the flat surface in humid environments. Based on our study, employing nanoporous layers is vital for nanogenerators either for power generation or active sensor applications at high humidity conditions.

Enhancement of self-powered humidity sensing of graphene oxide-based triboelectric nanogenerators by addition of graphene oxide nanoribbons

A triboelectric nanogenerator (TENG) electrode sensitive to the adsorption of water molecules has been introduced to create a self-powered humidity sensor. Graphene oxide (GO) nanosheets and graphene oxide nanoribbon (GONR) possessing oxygenated functional groups, as well as high dielectric constants, have been proposed as appropriate candidates for this purpose. GO papers have been fabricated in three forms, i.e. pure  GO paper, uniform composites of GONR and GO, and double-layer structures of GONR on top of  GO. Results showed that all of the prepared paper-based TENGs revealed excellent performances by maximum output voltage above 300 V. As active humidity sensors, the maximum voltage response values of 57%, 124%, and 78% were obtained for GO, GONR+GO, and GONR/GO TENGs, respectively. Besides high sensitivity and precision of all variants, GO+GONR TENG demonstrated a rapid response/recovery behavior (0.3/0.5 s). This phenomenon can be attributed to the higher oxygenated groups and defects on the edges of GONR, which leads to facilitating the bulk diffusion of water molecules. Our results open new avenues of GONR application as an additive to enhance the performance of self-powered humidity sensors, as well as conventional hygrometers.

The effect of patient positioning (prone or supine) on the dose received by small bowel in pelvic radiotherapy in rectal cancer patients

PURPOSE

The small bowel is a main dose-limiting organ in pelvic radiotherapy in the patients with rectal cancer. Conventionally, pelvic radiotherapy of patients with rectal cancer is performed in the prone position.

MATERIAL AND METHODS

Thirty-nine patients underwent CT planning scan in the treatment position (20 patients in prone position group and 19 patients in supine position group). After radiation treatment planning optimization, the volumes of the irradiated small intestines were investigated.

RESULTS

The volume of irradiated small bowel was higher in the supine position (mean difference; 36,274 cm³). However, it was not statistically significant (P value=0.187) CONCLUSION: Supine position could be accepted for the patients undergoing preoperative rectal cancer chemo-radiation.

Carbon Nanotube Modified Microelectrode Array for Neural Interface

Carbon nanotubes (CNTs) coatings have been shown over the past few years as a promising material for neural interface applications. In particular, in the field of nerve implants, CNTs have fundamental advantages due to their unique mechanical and electrical properties. In this study, carbon nanotubes multi-electrode arrays (CNT-modified-Au MEAs) were fabricated based on gold multi-electrode arrays (Au-MEAs). The electrochemical impedance spectra of CNT-modified-Au MEA and Au-MEA were compared employing equivalent circuit models. In comparison with Au-MEA (17 Ω), CNT-modified-Au MEA (8 Ω) lowered the overall impedance of the electrode at 1 kHz by 50%. The results showed that CNT-modified-Au MEAs have good properties such as low impedance, high stability and durability, as well as scratch resistance, which makes them appropriate for long-term application in neural interfaces.

Room temperature and high response ethanol sensor based on two dimensional hybrid nanostructures of WS2/GONRs

Here in this research, room temperature ethanol and humidity sensors were prepared based on two dimensional (2D) hybrid nanostructures of tungsten di-sulfide (WS2) nanosheets and graphene oxide nanoribbons (GONRs) as GOWS. The characterization results based on scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (ESD), Raman spectroscopy and X-ray diffraction (XRD) analysis confirmed the hybrid formations. Ethanol sensing of drop-casted GOWS films on SiO2 substrate indicated increasing in gas response up to 5 and 55 times higher compared to pristine GONRs and WS2 films respectively. The sensing performance of GOWS hybrid nanostructures was investigated in different concentrations of WS2, and the highest response was about 126.5 at 1 ppm of ethanol in 40% relative humidity (R.H.) for WS2/GONRs molar ratio of 10. Flexibility of GOWS was studied on Kapton substrate with bending radius of 1 cm, and the gas response decreased less than 10% after 30th bending cycles. The high response and flexibility of the sensors inspired that GOWS are promising materials for fabrication of wearable gas sensing devices.

Fabrication of flexible self-powered humidity sensor based on super-hydrophilic titanium oxide nanotube arrays

Stable and flexible super-hydrophilic nanotubular-based titanium oxide electrode has been utilized as the active electrode of self-powered humidity sensor. TiO₂ nanotubular electrodes fabricated through anodization method and utilized in combination with Kapton electrode as the triboelectric nanogenerator (TENG). Vertical contact-separation mode TENG performance has been examined in various range of frequencies and the maximum output voltage and current more than 300 V and 40 μA respectively with maximum power of 1.25 ± 0.67 mW has been achieved at 4 Hz. The fabricated TENG has been employed as the active self-powered humidity sensor. Super-hydrophilic feature of TiO₂ nanotubes resulted in full absorption of water molecules, and noticeable decrease in charge transfer across two triboelectric materials upon increasing humidity. The TiO₂-based TENG sensor was exposed to various relative humidity (RH) and the results showed that by increasing the humidity the output voltage and output current decreased from 162.24 ± 35.99 V and 20.4 ± 4.93 μA at RH = 20% to 37.92 ± 1.54 V at RH = 79% and 40.87 88 6.88 ± 1.7 μA at RH = 84%, respectively, Which shows the responsivity more than 300%. This method of measuring humidity has a simple and cost-effective fabrication that has various applications in many fields such as industry and medicine.

Graphene Oxide Papers in Nanogenerators for Self-Powered Humidity Sensing by Finger Tapping

Triboelectric nanogenerators (TENGs) offer an emerging market of self-sufficient power sources, converting the mechanical energy of the environment to electricity. Recently reported high power densities for the TENGs provide new applications opportunities, such as self-powered sensors. Here in this research, a flexible graphene oxide (GO) paper was fabricated through a straightforward method and utilized as the electrode of TENGs. Outstanding power density as high as 1.3 W.m^-2, an open-circuit voltage up to 870 V, and a current density of 1.4 µA.cm^-2 has been extracted in vertical contact-separation mode. The all-flexible TENG has been employed as a self-powered humidity sensor to investigate the effect of raising humidity on the output voltage and current by applying mechanical agitation in two forms of using a tapping device and finger tapping. Due to the presence of superficial functional groups on the GO paper, water molecules are inclined to be adsorbed, resulting in a considerable reduction in both generated voltage (from 144 V to 14 V) and current (from 23 µA to 3.7 µA) within the range of relative humidity of 20% to 99%. These results provide a promising applicability of the first suggested sensitive self-powered GO TENG humidity sensor in portable/wearable electronics.

Sandblasting improves the performance of electrodes of miniature electrical impedance tomography via double layer capacitance

Effect of sandblasting of the copper electrode structures before deposition of gold thin film for micro electrical impedance tomography (EIT) system has been studied experimentally. The comparison has been performed on the unmodified copper electrodes and the sandblasted electrodes before deposition of gold layer, using structural analysis while their performance in EIT system has been measured and analyzed. The results of scanning electron microscopy and atomic force microscopy show that the sandblasting of the electrodes results in the deposition of gold film with smaller grain size and uniformly, comparing to the unmodified structure. The measurement of impedance shows that the sandblasting will increase the double layer capacitance of electrode structure which improves the impedance measurement accordingly.

Investigation of electron boost radiotherapy in patients with breast cancer: Is a direct electron field optimal?

PURPOSE

Historically, electron boost dose mainly was delivered by a direct field in adjuvant radiotherapy of breast cancer. In this prospective study, we investigated direct electron field, in terms of optimal coverage of tumour bed volume following localization using ultrasound and surgical clips.

MATERIAL AND METHODS

First, for all 24 patients, a breast sonographer drew perimeter of tumour bed on the breast skin. Then an electron boost field was outlined on the demarcated territory, and a lead wire marker compatible with CT scan was placed on the field borders by a 2cm margin. After CT scan simulation, all patients underwent adjuvant whole breast irradiation with 3D-conformal radiotherapy to 50Gy in 25 fractions. Then for boost radiotherapy, lead wire in CT images was countoured as electron boost field. Also, the tumour bed was contoured based on surgical clips (true clinical target volume and true planning target volume). Electron treatment planning was done for electron boost field. Finally isodose coverages for true planning target volume investigated.

RESULTS

On average, 16.68% of clips planning target volume (true planning target volume; range: 0.00 to 95%) received 90% oor more of the prescribed dose when the electron treatment plan was made. Isodose curves does not provide adequate coverage on the tumour bed (clips planning target volume) when electron boost treatment planning was generated for electron boost field (en face electron field). In fact, a part of target (planning target volume-c) is missed and more doses is absorbed in normal tissue.

CONCLUSIONS

Electron boost treatment planning (an en face electron field) following tumour bed localization using ultrasonography does not provide an optimized coverage of tumour bed volume.

Effect of sulfonating agent and ligand chemistry on structural and optical properties of CuSbS2 particles prepared by heat-up method

CuSbS₂ particles were prepared by a facile heat-up method to investigate the effect of sulfur source and ligand chemistry.

Influence of Perovskite Morphology on Slow and Fast Charge Transport and Hysteresis in the Perovskite Solar Cells

We have investigated the influence of perovskite morphology on slow and fast charge transport in the perovskite solar cells. Solar cells with different perovskite cuboid sizes (50-300 nm) have been fabricated using various methylammonium iodide concentrations. Both the low-frequency capacitance and hysteresis are maximum for the cell with the largest perovskite grains (300 nm). The low-frequency capacitance is about three orders of magnitude greater than the intermediate frequency capacitance, indicating the great role of ions on the slow responses and hysteresis. The measurement of open-circuit voltage decay indicates that for the large grains of 300 nm up to 70% of V_oc remains across the cell, even after passing ∼40 s. Such a long time V_oc decay demonstrates the large accumulation of the ions at the perovskite interfaces with electron and hole transport layers, which conduct slow redistribution of the charges after the light is turned off.

TiO2/nanoporous silicon hybrid contact for heterojunction crystalline solar cell

Hole barrier contact as a remedy for easy fabrication of heterojunction crystalline solar cell.

Light harvesting and photocurrent generation by nanostructured photoelectrodes sensitized with a photosynthetic pigment: a new application for microalgae

Here in this study, successful conversion of visible light into electricity has been achieved through utilizing microalgal pigments as a sensitizer of nanostructured photo-electrode of dye-sensitized solar cells (DSSCs). For the first time, photosynthetic pigments extracted from microalgae grown in wastewater is employed to imitate photosynthesis process in bio-molecule-sensitized solar cells. Two designs of photoanode were employed: 10 μm nanoparticular TiO2 electrode and 20 μm long self-ordered, vertically oriented nanotube arrays of titanium dioxide films. Microalgal photosynthetic pigments are loaded on nanostructured electrodes and their photovoltaic performances have been investigated. To optimize the performance of solar cell, the time course of dye loading on the nanocrystalline TiO2 films is investigated. The performance of the cells is characterized by measuring the current-voltage (I-V) curves under AM1.5 (100 mW cm(-2)) irradiation condition. The highest efficiency of around ∼ 1%, quite comparable to green plants, is found for sensitizer-loading time of 1h.

Comparison of trap-state distribution and carrier transport in nanotubular and nanoparticulate TiO(2) electrodes for dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) with nanotubular TiO(2) electrodes of varying thicknesses are compared to DSCs based on conventional nanoparticulate electrodes. Despite the higher degree of order in one-dimensional nanotubular electrodes, electron transport times and diffusion coefficients, determined under short-circuit conditions, are comparable to those of nanoparticulate electrodes. The quasi-Fermi level, however, is much lower in the nanotubes, suggesting a lower concentration of conduction band electrons. This provides evidence for a much higher diffusion coefficient for conduction band electrons in nanotubes than in nanoparticulate films. The electron lifetime and the diffusion length are significantly longer in nanotubular TiO(2) electrodes than in nanoparticulate films. Nanotubular electrodes have a trap distribution that differs significantly from nanoparticulate electrodes; they possess relatively deeper traps and have a characteristic energy of the exponential distribution that is more than two times that of nanoparticulate electrodes.

Identification of Malassezia species isolated from Iranian seborrhoeic dermatitis patients

BACKGROUND AND OBJECTIVES

In recent years, the genus Malassezia has come to be considered important in the etiology of seborrhoeic dermatitis (SED). The aim of present study was identification of Malassezia species on the lesions of Iranian SED patients.

METHODS

100 patients with SED were enrolled in the study. The patients were evaluated both clinically for the severity of SED and microscopically for the presence of the yeast Malassezia. Diagnosis of Malassezia was made after the yeast Malassezia was microscopically observed on skin scales stained with methylene blue. All samples were also cultivated on Leeming and Notman and Sabouraud's dextrose agar culture media. The agar plates were incubated at 32 degrees C for 2 weeks and evaluated for the existence of growth every day for one week. Identification of isolated yeast was based on morphological and physiological characteristics.

RESULTS

From 100 patients with SED, 60% were female. The age range was 12-65 years with median 27.3 years. The highest prevalence of SED was seen in 20-29 years age group. 59% and 41% of patients had local and generalized lesions, respectively. 58% of patients showed lesion on scalp. Microscopic examination of skin scales was positive in 100% of SED lesions. 96% of patients showed more than 1-3 yeasts in each microscopic field whereas only 4% patients showed 1-3 yeasts in whole slide. Totally, 77% of the specimens yielded Malassezia in culture. Malassezia globosa was the most commonly isolated Malassezia species (55.8%). Malassezia globosa had also most frequencies on scalp and face lesions. Malassezia furfur had most frequency on trunk lesions.

CONCLUSION

The results of our study showed high recovery rate of Malassezia species on lesions of patients with SED. So it might be playing a causative role in the etiology of this disease.