Mechanical Stimulation Research Articles

A Biomimetic Passive Mechanotransduction Mechanism Based on Interfacial Regulation of Ionic p-n Junctions.

Natural skin receptors use ions as signal carriers, while most of the developed artificial tactile sensors utilize electrons as information carriers. To imitate the biological ionic sensing behavior, here, we present a kind of biomimetic, ionic, and fully passive mechanotransduction mechanism leveraging mechanical modulation of interfacial ionic p-n junction (IPNJ) through microchannels. Sensors based on this mechanism do not rely on an external power supply and can encode external tactile stimuli into highly analogous signal outputs to those of natural skin receptors, in terms of both signal type (i.e., ionic potential difference) and signal intensity (≈120 mV). More importantly, the instant interfacial IPNJ regulation characteristic endows the sensors with superior performance when compared to the state-of-the-art piezoionic sensors, including a low detection limit of 0.01 N, fast response/recovery speeds (16 ms/16 ms), ultralow power consumption (pW level), excellent reproducibility (over 100,000 cycles), and good capabilities to resolve both static and dynamic mechanical stimulations. As demonstrations, machine-learning-assisted high accuracy (over 99%) surface texture recognition and object classification are successfully demonstrated with the sensors integrated on robotic hands. This work enriches the family of mechanical sensing mechanisms and provides a path to mimicking natural tactile sensory systems for smart skins, artificial prostheses, and intelligent robots.

Biophysical aspects of mechanotransduction in cells and their physiological/biological implications in vocal fold vibration: a narrative review

Mechanotransduction is a crucial property in all organisms, modulating cellular behaviors in response to external mechanical stimuli. Given the high mobility of vocal folds, it is hypothesized that mechanotransduction significantly contributes to their tissue homeostasis. Recent studies have identified mechanosensitive proteins in vocal fold epithelia, supporting this hypothesis. Voice therapy, which, involves the mobilization of vocal folds, aims to rehabilitate vocal function and restore homeostasis. However, establishing a direct causal link between specific mechanical stimuli and therapeutic benefits is challenging due to the variability in voice therapy techniques. This challenge is further compounded when investigating biological benefits in humans. Vocal fold tissue cannot be biopsied without significant impairment of the vibratory characteristics of the vocal folds. Conversely, studies using vocal fold mimetic bioreactors have demonstrated that mechanical stimulation of vocal fold fibroblasts can lead to highly heterogeneous responses, depending on the nature and parameters of the induced vibration. These responses can either aid or impede vocal fold vibration at the physiological level. Future research is needed to determine the specific mechanical parameters that are biologically beneficial for vocal fold function.

A multifunctional sensor for cell traction force, matrix remodeling and biomechanical assays in self-assembled 3D tissues in vitro.

Cell-matrix interactions, mediated by cellular force and matrix remodeling, result in dynamic reciprocity that drives numerous biological processes and disease progression. Currently, there is no available method for directly quantifying cell traction force and matrix remodeling in three-dimensional matrices as a function of time. To address this long-standing need, we developed a high-resolution microfabricated device that enables longitudinal measurement of cell force, matrix stiffness and the application of mechanical stimulation (tension or compression) to cells. Here a specimen comprising of cells and matrix self-assembles and self-integrates with the sensor. With primary fibroblasts, cancer cells and neurons we have demonstrated the feasibility of the sensor by measuring single or multiple cell force with a resolution of 1 nN and changes in tissue stiffness due to matrix remodeling by the cells. The sensor can also potentially be translated into a high-throughput system for clinical assays such as patient-specific drug and phenotypic screening. We present the detailed protocol for manufacturing the sensors, preparing experimental setup, developing assays with different tissues and for imaging and analyzing the data. Apart from microfabrication of the molds in a cleanroom (one time operation), this protocol does not require any specialized skillset and can be completed within 4-5 h.

Melatonin antagonizes bone loss induced by mechanical unloading via IGF2BP1-dependent m6A regulation

Disuse bone loss is prone to occur in individuals who lack mechanical stimulation due to prolonged spaceflight or extended bed rest, rendering them susceptible to fractures and placing an enormous burden on social care; nevertheless, the underlying molecular mechanisms of bone loss caused by mechanical unloading have not been fully elucidated. Numerous studies have focused on the epigenetic regulation of disuse bone loss; yet limited research has been conducted on the impact of RNA modification bone formation in response to mechanical unloading conditions. In this study, we discovered that m6A reader IGF2BP1 was downregulated in both osteoblasts treated with 2D clinostat and bone tissue in HLU mice. Supplementing IGF2BP1 could promote osteoblast proliferation and partially alleviate the adverse effects of mechanical unloading on bone formation. Mechanistically, IGF2BP1 inhibited the degradation of Lef1 mRNA by directly binding to its mRNA and recognizing the m6A modification. Furthermore, LEF1 promoted osteoblast proliferation by upregulating c-Myc and Cyclin D1 expression, as well as participated in mediating IGF2BP1-induced osteoblast activity under mechanical unloading. Notably, Melatonin (MT) might participate in the regulation of the IGF2BP1/LEF1 axis, thereby regulating the proliferation of osteoblasts and bone formation. Collectively, this study revealed a new insight into the regulation of the MT/IGF2BP1/LEF1 pathway in the process of unloading-induced bone loss, which could potentially contribute to establishing therapeutic strategies for disuse osteoporosis.

Cell Mechanisms of Post-Mortem Excitability of Skeletal Muscle.

Background/Objectives: The excitability of skeletal muscle is a less-known post-mortem supravital phenomenon in human bodies, and it can be used to estimate the post-mortem interval. We conducted a field study in the Netherlands to investigate the applicability of muscle excitability (SMR) by mechanical stimulation for estimating the post-mortem interval in daily forensic practice. Knowledge concerning the post-mortem cell mechanisms accounting for the post-mortem excitability of skeletal muscle is lacking. Cell mechanisms are the specific intracellular and biochemical processes responsible for post-mortem muscle excitability. Methods: We have studied the theoretical backgrounds of the cell mechanisms that might be responsible for post-mortem muscle excitability, by performing literature research via the databank PubMed. Results: Based on the current available literature, in our opinion the intracellular changes in muscle cells that are responsible for SMR resemble the intracellular processes responsible for muscle fatigue due to energy exhaustion in the living. Conclusions: We hypothesize two pathways, depending on the level of energy in the muscle cell, that could be responsible for post-mortem muscle excitability by mechanical stimulation.

How spinal GABAergic circuits modulate cerebral processing of postsurgical pain.

Post-surgical pain affects millions each year, hindering recovery and quality of life. Surgical procedures cause tissue damage and inflammation, leading to peripheral and central sensitization, resulting in pain at rest or hyperalgesia to mechanical stimuli, among others. In a rat model for post-surgical pain, spinal GABAergic transmission via GABAA receptors reduces mechanical hypersensitivity but has no effect on pain at rest. While fMRI studies show consistent brain activity changes during mechanical stimulation in post-surgical pain, central processing of pain at rest and the role of spinal GABAergic circuits on surgical pain processing is currently unclear. The aim of this study was to evaluate the influence of an acute surgical incision, a proxy for post-surgical pain, on the cerebral processing of pain at rest and mechanical hypersensitivity, and to assess the influence of spinal GABAA-circuits on this processing. In rats, a unilateral incision injury affected sensorimotor and thalamo-limbic subnetworks at rest and following mechanical stimulation, indicating changes in neural processing relevant to pain at rest and mechanical hypersensitivity in post-surgical pain. Enhancing spinal GABAergic tone increased functional connectivity (FC) in parts of these subnetworks during mechanical stimulation, but not at rest, highlighting spino-cerebral interactions in post-surgical pain regulation relevant for mechanical hypersensitivity and potentially the development of chronic pain after surgery but likely not for pain at rest. These findings underscore the complex and interconnected nature of brain networks in post-surgical pain processing, and provide insights into potential spinal targets for pharmacological intervention to alleviate post-surgical pain and prevent it's chronification.

Comparative Study of Trifunctionalization for Enhanced Energy and Thermal Stability in Zwitterionic Fused Triazole Skeletons.

In this work, two energetic compounds 5-(3-iminio-6-nitro-3H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2(7H)-yl)tetrazol-1-ide (TT) and 3-nitro-7-(2H-tetrazol-5-yl)-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-6-amine (FT) were successfully synthesized from the same compound 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazolium (TATOT). Both compounds contain three explosophores, amino, nitro, and tetrazole, on the fused ring. Through different functional group arrangements, TT possesses higher density and good thermal stability. FT exhibits a low sensitivity to mechanical stimulation. Both compounds show promising energetic performance properties.

Oscillatory fluid flow enhanced mineralization of human dental pulp cells

The purpose of this study is to evaluate the optimum frequency of oscillatory fluid flow (OFF) for increasing osteogenesis in human dental pulp cells (DPCs) in an incubating rocking shaker. DPCs from 3 donors were cultured in an osteogenic induction medium (OIM) and mechanical stimulation was applied using an incubating rocking shaker at frequencies of 0 (control), 10, 20, 30, and 40 round per minute (RPM) for 1 h/day, 5 days/week. Cell proliferation was measured using total protein quantification, and osteogenic activity was measured by alkaline phosphatase (ALP) activity, calcium deposition, and collagen production on days 7, 14, and 21 of culture. Results of DPCs morphology in the 30 RPM group were more clustered and formed interconnections between cells. Results of DPC proliferation and collagen production showed no significant differences between the experiment groups. The ALP activity on day 7 and 14, and calcium deposition on day 21 of the 30 RPM group were significantly higher than the control groups. Thus 30 RPM is likely an effective frequency for increasing calcium deposition. This study uses strategies in Tissue Engineering followed the research topic about an application of human cells to stimulate oral and maxillofacial hard tissue regeneration. In the future, the mineralization of DPCs could be enhanced by using an incubating rocking shaker at 30 RPM in the lab to create a cell sheet. The mineralized cell sheet could then be implanted into the patient for bone repair of orofacial defects.

Deciphering the Proteome and Phosphoproteome of Peanut (Arachis hypogaea L.) Pegs Penetrating into the Soil.

Peanut (Arachis hypogaea L.) is one of the most important crops for oil and protein production. The unique characteristic of peanut is geocarpy, which means that it blooms aerially and the peanut gynophores (pegs) penetrate into the soil, driving the fruit underground. In order to fully understand this phenomenon, we investigated the dynamic proteomic and phosphoproteomic profiling of the pegs aerially and underground in this study. A total of 6859 proteins and 4142 unique phosphoproteins with 10,070 phosphosites were identified. The data were validated and quantified using samples randomly selected from arial pegs (APs) and underground pegs (UPs) by parallel reaction monitoring (PRM). Function analyses of differentially abundant proteins (DAPs) and differentially regulated phosphoproteins (DRPPs) exhibited that they were mainly related to stress response, photosynthesis, and substance metabolism. Once the pegs successfully entered the soil, disease-resistant and stress response proteins, such as glutathione S-transferase, peroxidase, and cytochrome P450, significantly increased in the UP samples in order to adapt to the new soil environment. The increased abundance of photosynthesis-associated proteins in the UP samples provided more abundant photosynthetic products, which provided the preparation for subsequent pod development. Phosphoproteomics reveals the regulatory network of the synthesis of nutrients such as starch, protein, and fatty acid (FA). These results provide new insights into the mechanism, indicating that after the pegs are inserted into the soil, phosphorylation is involved in the rapid elongation of the pegs, accompanied by supplying energy for pod development and preparing for the synthesis of metabolites during pod development following mechanical stimulation and darkness.

Enhanced intestinal epithelial co-culture model with orbital mechanical stimulation: a proof-of-concept application in food nanotoxicology.

Current in vitro intestinal models lack the mechanical forces present in the physiological environment, limiting their reliability for nanotoxicology studies. Here, we developed an enhanced Caco-2/HT29-MTX-E12 co-culture model incorporating orbital mechanical stimulation to better replicate intestinal conditions and investigate nanoparticle interactions. We established co-cultures under static and dynamic conditions, evaluating their development through multiple approaches including barrier integrity measurements, gene expression analysis, and confocal microscopy. We introduced novel quantitative analysis of dome formation as a differentiation marker and demonstrated the model application by investigating cellular responses to titanium dioxide (TiO₂) nanoparticles in a digested food matrix. Dynamic conditions accelerated epithelial differentiation, achieving functional barrier properties by day 14 rather than day 21, with enhanced mucin production and more organized three-dimensional structure. Mechanical stimulation selectively promoted goblet cell differentiation without affecting general epithelial markers. The optimized model successfully detected concentration-dependent oxidative stress responses to TiO₂ exposure, revealing cellular dysfunction preceding membrane damage. This improved co-culture system provides a better physiological platform for nanotoxicology studies. By incorporating mechanical forces, each cell type exhibits more representative behavior, creating a more realistic experimental setup. The model bridges the gap between simple monocultures and complex 3D systems, offering a practical approach for investigating nanoparticle-epithelium interactions in a food-relevant context.

Sensory experience controls dendritic structure and behavior by distinct pathways involving degenerins.

Dendrites are crucial for receiving information into neurons. Sensory experience affects the structure of these tree-like neurites, which, it is assumed, modifies neuronal function, yet the evidence is scarce, and the mechanisms are unknown. To study whether sensory experience affects dendritic morphology, we use the Caenorhabditis elegans' arborized nociceptor PVD neurons, under natural mechanical stimulation induced by physical contacts between individuals. We found that mechanosensory signals induced by conspecifics and by glass beads affect the dendritic structure of the PVD. Moreover, developmentally isolated animals show a decrease in their ability to respond to harsh touch. The structural and behavioral plasticity following sensory deprivation are functionally independent of each other and are mediated by an array of evolutionarily conserved mechanosensory amiloride-sensitive epithelial sodium channels (degenerins). Calcium imaging of the PVD neurons in a micromechanical device revealed that controlled mechanical stimulation of the body wall produces similar calcium dynamics in both isolated and crowded animals. Our genetic results, supported by optogenetic, behavioral, and pharmacological evidence, suggest an activity-dependent homeostatic mechanism for dendritic structural plasticity, that in parallel controls escape response to noxious mechanosensory stimuli.

The response of Petunia × atkinsiana 'Pegasus Special Burgundy Bicolor’ to mechanical stress encompassing morphological changes as well as physiological and molecular factors

In 1973, Jaffe identified and characterized the phenomenon of thigmomorphogenesis, also referred to as mechanical stress (MS) or mechanical stimulation in plants. Previous studies on petunia plants demonstrated that MS significantly affects growth dynamics. As a response to MS, petunias exhibit increased levels of indole-3-acetic acid (IAA) oxidase and peroxidase, although the active transport of endogenous IAA remains unaffected. Furthermore, earlier research has shown that MS inhibits the synthesis of IAA and gibberellin (GA3), with noticeable effects on the 14th day of mechanical stimulation. The current experiment made on Petunia × atkinsiana 'Pegasus Special Burgundy Bicolor’ focused on evaluating the morphological and physiological responses to MS, along with the expression of specific touch-responsive genes such as GH3.1, which is involved in auxin metabolism, and calmodulins (CaMs), playing an important role in stress responses. GH3.1 expression was found to be negatively correlated with IAA synthesis while positively correlated with GAs synthesis and IAA oxidase activity. Variable expression patterns were observed in the calmodulins: CAM53 and CAM81 expression positively correlated with IAA synthesis and plant height, whereas CAM72 expression was positively associated with GAs levels and IAA oxidase activity in plants touched 80× per day, but all of them were negatively related to IAA content and shoot increment, while positively related to GAs synthesis and IAA oxidase activity.

The C. elegans uv1 neuroendocrine cells provide mechanosensory feedback of vulval opening.

Neuroendocrine cells react to physical, chemical, and synaptic signals originating from tissues and the nervous system, releasing hormones that regulate various body functions beyond the synapse. Neuroendocrine cells are often embedded in complex tissues making direct tests of their activation mechanisms and signaling effects difficult to study. In the nematode worm C. elegans, four uterine-vulval (uv1) neuroendocrine cells sit above the vulval canal next to the egg-laying circuit, releasing tyramine and neuropeptides that feedback to inhibit egg laying. We have previously shown uv1 cells are mechanically deformed during egg laying, driving uv1 Ca2+ transients. However, whether egg-laying circuit activity, vulval opening, and/or egg release triggered uv1 Ca2+ activity was unclear. Here we show uv1 responds directly to mechanical activation. Optogenetic vulval muscle stimulation triggers uv1 Ca2+ activity following muscle contraction even in sterile animals. Direct mechanical prodding with a glass probe placed against the worm cuticle triggers robust uv1 Ca2+ activity similar to that seen during egg laying. Direct mechanical activation of uv1 cells does not require other cells in the egg-laying circuit, synaptic or peptidergic neurotransmission, or TRPV and Piezo channels. EGL-19 L-type Ca2+ channels, but not P/Q/N-type or Ryanodine Receptor Ca2+ channels, promote uv1 Ca2+ activity following mechanical activation. L-type channels also facilitate the coordinated activation of uv1 cells across the vulva, suggesting mechanical stimulation of one uv1 cells cross-activates the other. Our findings show how neuroendocrine cells like uv1 report on the mechanics of tissue deformation and muscle contraction, facilitating feedback to local circuits to coordinate behavior.Significance Statement Neuroendocrine cells respond to diverse physical and chemical signals from the body, releasing hormones that control reproduction, gut motility, and fight or flight responses. Neuroendocrine cells are often found embedded in complex tissues, complicating studies of how they are activated. Using the genetic and experimental accessibility of C. elegans, we find the uv1 neuroendocrine cells of the egg-laying motor behavior circuit respond directly to mechanical stimulation and vulval opening. We show that L-type voltage-gated Ca2+ channels facilitate uv1 mechanical activation and coordinate cell activation across the vulval opening. In contrast to other mechanically activated cells, uv1 activation does not require Piezo or TRPV channels. This work shows how neuroendocrine cells relay critical mechanosensory feedback to circuits that control reproduction.

Moringa oleifera L. Nanosuspension Extract Administration Affects Heat Shock Protein-10 and -70 under Orthodontics Mechanical Force In Vivo.

The mechanical stimulation known as orthodontic mechanical force (OMF) causes biological reactions in orthodontic tooth movement (OTM). Heat shock protein-70 (HSP-70) needs pro-inflammatory cytokines to trigger bone resorption in OTM; nevertheless, heat shock protein-10 (HSP-10), a "Alarmin" cytokine, should control these pro-inflammatory cytokines to get the best alveolar bone remodeling (ABR). Moringa oleifera L. nanosuspension extract (MONE) has anti-inflammatory, antioxidant, and ABR-stimulating properties. The aim of the study was to examine in vivo HSP-10 and HSP-70 expressions under OMF following MONE application in Wistar rats (Rattus norvegicus). A total of 36 Wistar rats (R. norvegicus) were split up into eight groups: one for treatment (OMF + MONE) and one for control (OMF + MONE administration for days 1, 7, 14, and 21). By employing nickel-titanium coil springs and using 10 g of light force per millimeter to implant the orthodontic device, the OMF was completed. According to the day of observation, all of the samples were sacrificed. To perform an immunohistochemistry investigation, the premaxilla of the sample was isolated. Tukey's Honest Significant Different (HSD) test (p < 0.05) was performed after an Analysis of Variance (ANOVA) analysis of the data. In both the OMF and MONE groups, HSP-70 peaked on day 14 and began to fall on day 21. HSP-10 peaked on day 21, but along with MONE, it also began to progressively decline on days 14 and 21, with significant differences (p < 0.05). According to immunohistochemistry evidence, postadministration of MONE markedly elevated HSP-10 but lowered HSP-70 expression in the alveolar bone of Wistar rats under OMF.

Local Administration of (-)-Epigallocatechin-3-Gallate as a Local Anesthetic Agent Inhibits the Excitability of Rat Nociceptive Primary Sensory Neurons.

While the impact of (-)-epigallocatechin-3-gallate (EGCG) on modulating nociceptive secondary neuron activity has been documented, it is still unknown how EGCG affects the excitability of nociceptive primary neurons in vivo. The objective of the current study was to investigate whether administering EGCG locally in rats reduces the excitability of nociceptive primary trigeminal ganglion (TG) neurons in response to mechanical stimulation in vivo. In anesthetized rats, TG neuronal extracellular single unit recordings were made in response to both non-noxious and noxious mechanical stimuli. Following the administration of EGCG, the mean firing rate of TG neurons to both non-noxious and noxious mechanical stimuli significantly decreased in a dose-dependent manner (1-10 mM), and both the non-noxious and nociceptive mechanical stimuli experienced the maximum suppression of discharge frequency within 5 min. These inhibitory effects lasted for approximately 20 min. These findings suggest that the local injection of EGCG into the peripheral receptive field suppresses the responsiveness of nociceptive primary sensory neurons in the TG, almost equal to that of the local anesthetic, 1% lidocaine. As a result, the local application of EGCG as a local anesthetic could alleviate nociceptive trigeminal pain that does not result in side effects, thereby playing a significant role in pain management.

Characterisation of the effects of the chemotherapeutic agent paclitaxel on neuropathic pain-related behaviour, anxiodepressive behaviour, cognition, and the endocannabinoid system in male and female rats.

Paclitaxel (PTX) is a commonly used chemotherapeutic drug, however, one of its major adverse effects is chronic neuropathic pain, with the incidence being higher in women than in men. The neurobiological mechanisms behind this sex difference are still largely unclear, and the endocannabinoid system, which exhibits sexual dimorphism and plays a key role in pain regulation, is a promising area for further studies. The present study aimed to characterise pain-, cognition-, anxiety-, and depression-related behaviours in male and female rats following PTX administration, and associated alterations in the endocannabinoid system. After the induction of the model, pain-related behaviours were assessed using von Frey, Acetone Drop and Hargreaves' tests, Novel Object Recognition and T-Maze Spontaneous Alternation tests were used for cognition-related behaviours, Elevated Plus Maze, Open Field, and Light Dark Box tests were used to assess anxiety-related behaviours, and Sucrose Preference, Sucrose Splash, and Forced Swim tests for depression-related behaviours. At each time point analysed, animals treated with PTX exhibited mechanical and cold hypersensitivity, with females displaying lower hind paw withdrawal thresholds to mechanical stimulation than males. No PTX-induced alterations in the other behavioural tests were detected. Post-mortem measurement of endocannabinoid and related N-acylethanolamine levels in spinal cord and discrete brain regions revealed a PTX-induced increase of 2-Arachidonoyl Glycerol (2-AG), N-Palmitoylethanolamine (PEA) and N-Oleoylethanolamine (OEA) levels in the amygdala of male and female animals, but not in the other areas. Collectively, these results suggest that PTX causes similar long-lasting hypersensitivity to mechanical and cold stimuli, but not heat, in rats of both sexes, effects accompanied by increases in amygdalar levels of endocannabinoids and N-acylethanolamines.

Osteogenic differentiation of mesenchymal stem cell on poly sorbitol sebacate scaffold under shear stress in a bioreactor.

Mechanical loading plays a pivotal role in regulating bone anabolic processes. Understanding the optimal mechanical loading parameters for cellular responses is critical for advancing strategies in orthopedic bioreactor-based bone tissue engineering. This study developed a poly (sorbitol sebacate) (PSS) filmscaffold with a sorbitol-to-sebacic acid molar ratio of 1:4. The scaffold underwent extensive characterization, including physical and mechanical property evaluations, biocompatibility assessments, and cell adhesion analysis. The Young's modulus of the PSS polymer was determined to be 6.81 ± 0.44 MPa under dry conditions, 6.37 ± 1.09 MPa in a wet state, and 6.38 ± 0.71 MPa after ethanol washing (70 %). The average contact angle of the PSS film was measured at 88.806 ± 1.644°, indicating moderate hydrophilicity. To investigate the osteogenic potential, a fluid flow inducing a shear stress of 1 Pa at a frequency of 1 Hz was applied to mesenchymal stem cells (MSCs) cultured on the PSS scaffold. Cells were exposed to dynamic fluid flow for one hour daily on days 4, 5, 6, and 7 of culture, followed by a static culture period of 14 days. The expression of osteogenic differentiation markers, including osteopontin (OPN), osteocalcin (OCN), type I collagen, and calcium deposition, was significantly elevated under dynamic conditions compared to static culture. This study highlights the importance of mechanical stimulation in enhancing MSC osteogenesis and underscores the osteoconductive properties of the PSS scaffold. These findings provide valuable insights into scaffold design and mechanical loading strategies for laboratory-based bone tissue engineering applications.

Stretchable impedance electrode array with high durability for monitoring of cells under mechanical and chemical stimulations.

Electrochemical impedance spectroscopy (EIS) serves as a non-invasive technique for assessing cell status, while mechanical stretching plays a pivotal role in stimulating cells to emulate their natural environment. Integrating these two domains enables the concurrent application of mechanical stimulation and EIS in a stretchable cell culture system. However, challenges arise from the difficulty in creating a durable and stable stretchable impedance electrode array. To overcome this limitation, we have developed a cell culture system integrated with a stretchable impedance electrode array (SIEA). This design enabled impedance monitoring during cell proliferation under mechanical stimulation over a long period of time due to the high mechanical durability and electrochemical stability of the SIEA. Our evaluation also involved testing the cytotoxicity of doxorubicin on H9C2 cells directly on the SIEA. The results underscore the significant potential of our SIEA device as an effective tool for monitoring cells subjected to mechanical stimulation and as a platform for drug toxicity testing.

A multi-functional platform for stimulating and recording electrical responses of SH-SY5Y cells.

In recent years, multifunctional cell regulation on a single chip has become an imperative need for cell research. In this study, a novel multi-functional micro-platform integrating wireless electrical stimulation, mechanical stimulation and electrical response recording of cells was proposed. Controlling cell fate by photoexcited radio stimulation of cells on photosensitive films can precisely orchestrate biological activities. This is the first report of combining hydrogenated amorphous silicon (a-Si:H) photosensitive films and a 532 nm green laser for cell stimulation and electrical response recording. Remote wireless electrical stimulation of nerve cells through photoelectric effects based on photosensitive films evoked a change in membrane potential and promoted the neurite growth and neuronal differentiation. These effects were confirmed in a cell model of the human neuroblastoma cell line. The electrical response of cells demonstrated that the photocurrent generated by laser irradiation of the photosensitive film induced a redistribution of ions inside and outside the cell. Furthermore, a mechanical stimulus was applied to cells using a probe placed above them. The chip was used as a signal output to simultaneously obtain the electrical response of cells. The ability of photosensitive films to precisely excite cellular activity offers a novel prospect for wireless electrical stimulation. This work provides a promising strategy for the design of multi-functional biological devices based on a single chip.

Development of an Efficient, Lead-Free Piezoelectric Nanogenerator Utilizing PVDF: MnO2-Bi2WO6: RGO Composite Fiber for Self-Powered Sensing and Biomechanical Energy Harvesting

In this study, we have fabricated a highly efficient, environmentally safe, and flexible piezoelectric nanogenerator (PENG) utilizing a composite material comprising manganese oxide-bismuth tungstate (MnO2-Bi2WO6), polyvinylidene fluoride (PVDF), and reduced graphene oxide (RGO) by an optimized electrospinning technique. The PENG constructed with aluminum-based electrodes demonstrates an open-circuit voltage of 5 V and a short-circuit current of 2 μA under the influence of a compressive force measuring 10 N at a frequency of 3 Hz. These measurements were 3.2 and 3.3 times higher, respectively, than those of the original PVDF PENG. Moreover, the optimized PENG achieved an instantaneous power density of 0.4 mW. The exceptional performance of the nanogenerator can be ascribed to the synergistic blend of the β-phase PVDF polymer, the non-centrosymmetric characteristics of MnO2-Bi2WO6 nanosheets, and the electrical conductivity provided by RGO. Additionally, to evaluate both its capacity for sensing and energy harvesting capabilities, the fabricated PENG was utilized for detecting diverse human movements and charging multiple capacitors. Observations revealed that mechanical stimulation could charge a capacitor with a capacity of 1 μF to 5 V within 2.4 s, suggesting a viable platform for removing the requirement of an external power source for operating portable devices. As a result, the created PENG exhibits considerable promise and can serve as a viable substitute for traditional power sources in self-sustaining devices, providing its stability and flexibility.