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1.
Bioact Mater ; 41: 30-45, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-39101029

RESUMO

Cataract patients look forwards to fewer postoperative complications and higher vision quality after surgery. However, the current intraocular lens (IOL) implanted after cataract surgery neither can adjust focal length in response to ciliary muscle contraction as natural lens nor have the ability to prevent postoperative complications. Herein, a thermosensitve Poloxamer based hybrid hydrogel with antibacterial anti-inflammatory and photothermal functional elements doping was designed and used as injectable, in situ curable, and adjustable IOL (FHTAB IOL). The FHTAB IOL was composed of thermosensitve triblock-polymer F127DA and a small amount of HAMA, combined with BP NS, TA, and Ag NPs. FHTAB IOL can be injected into the empty lens capsule after cataract surgery via an injectable thermos-gel under NIR illumination and then be rapidly cured to form a full-size IOL under short-time blue light irradiation. The designed injectable FHTAB IOL possesses high transparency and transmittance, with a refractive index similar to the natural lens and adjustable properties. It was stabilized as a refractive medium without any leakage in the eye. In addition, the TA and Ag NPs loaded in the FHTAB IOL displayed significant antibacterial and anti-inflammatory effects in vitro and vivo. This study presents a potentially effective new strategy for the development of multifunctional adjustable IOLs.

2.
Natl Sci Rev ; 11(7): nwae206, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39071099

RESUMO

Selective pressures have given rise to a number of SARS-CoV-2 variants during the prolonged course of the COVID-19 pandemic. Recently evolved variants differ from ancestors in additional glycosylation within the spike protein receptor-binding domain (RBD). Details of how the acquisition of glycosylation impacts viral fitness and human adaptation are not clearly understood. Here, we dissected the role of N354-linked glycosylation, acquired by BA.2.86 sub-lineages, as a RBD conformational control element in attenuating viral infectivity. The reduced infectivity is recovered in the presence of heparin sulfate, which targets the 'N354 pocket' to ease restrictions of conformational transition resulting in a 'RBD-up' state, thereby conferring an adjustable infectivity. Furthermore, N354 glycosylation improved spike cleavage and cell-cell fusion, and in particular escaped one subset of ADCC antibodies. Together with reduced immunogenicity in hybrid immunity background, these indicate a single spike amino acid glycosylation event provides selective advantage in humans through multiple mechanisms.

3.
Sci Rep ; 14(1): 15695, 2024 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-38977824

RESUMO

Hydrogels are extensively explored as biomaterials for tissue scaffolds, and their controlled fabrication has been the subject of wide investigation. However, the tedious mechanical property adjusting process through formula control hindered their application for diverse tissue scaffolds. To overcome this limitation, we proposed a two-step process to realize simple adjustment of mechanical modulus over a broad range, by combining digital light processing (DLP) and post-processing steps. UV-curable hydrogels (polyacrylamide-alginate) are 3D printed via DLP, with the ability to create complex 3D patterns. Subsequent post-processing with Fe3+ ions bath induces secondary crosslinking of hydrogel scaffolds, tuning the modulus as required through soaking in solutions with different Fe3+ concentrations. This innovative two-step process offers high-precision (10 µm) and broad modulus adjusting capability (15.8-345 kPa), covering a broad range of tissues in the human body. As a practical demonstration, hydrogel scaffolds with tissue-mimicking patterns were printed for cultivating cardiac tissue and vascular scaffolds, which can effectively support tissue growth and induce tissue morphologies.


Assuntos
Hidrogéis , Impressão Tridimensional , Engenharia Tecidual , Alicerces Teciduais , Alicerces Teciduais/química , Hidrogéis/química , Engenharia Tecidual/métodos , Humanos , Alginatos/química , Materiais Biocompatíveis/química , Resinas Acrílicas/química , Módulo de Elasticidade , Luz
4.
Nanomicro Lett ; 16(1): 242, 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38985378

RESUMO

Fire warning is vital to human life, economy and ecology. However, the development of effective warning systems faces great challenges of fast response, adjustable threshold and remote detecting. Here, we propose an intelligent self-powered remote IoT fire warning system, by employing single-walled carbon nanotube/titanium carbide thermoelectric composite films. The flexible films, prepared by a convenient solution mixing, display p-type characteristic with excellent high-temperature stability, flame retardancy and TE (power factor of 239.7 ± 15.8 µW m-1 K-2) performances. The comprehensive morphology and structural analyses shed light on the underlying mechanisms. And the assembled TE devices (TEDs) exhibit fast fire warning with adjustable warning threshold voltages (1-10 mV). Excitingly, an ultrafast fire warning response time of ~ 0.1 s at 1 mV threshold voltage is achieved, rivaling many state-of-the-art systems. Furthermore, TE fire warning systems reveal outstanding stability after 50 repeated cycles and desired durability even undergoing 180 days of air exposure. Finally, a TED-based wireless intelligent fire warning system has been developed by coupling an amplifier, analog-to-digital converter and Bluetooth module. By combining TE characteristics, high-temperature stability and flame retardancy with wireless IoT signal transmission, TE-based hybrid system developed here is promising for next-generation self-powered remote IoT fire warning applications.

5.
Artigo em Inglês | MEDLINE | ID: mdl-39031874

RESUMO

PURPOSE: According to previous biomechanical studies, the success of meniscus root repair depends on the suture-meniscus interface and optimisation of this procedure seems to be critical. A progressive, reliable and adjustable knot has numerous advantages in meniscal repair since the surgeon can adapt and meticulously tune the final strength of the fixation. We hypothesised that a single passage of one tape at two different points of the posterior meniscal root with a modified Nice knot configuration may allow similar or superior fixation for root repair compared to the cinch stitch suture technique. METHODS: Posterior root repair of medial and lateral meniscus was performed on 26 porcine knees. In group (A), two simple cinch stitches were applied, and in group (B), a modified Nice knot was used in a crossmatch configuration. For both groups, two passages through the meniscus with a 2-mm braided tape were used, and a single transosseous tibial tunnel technique was performed and tested in pull-out conditions. RESULTS: The modified Nice knot showed an improved biomechanical performance considering the maximum failure load for both the medial (600.7 ± 77.5 N) and lateral (686.1 ± 83.5 N) (p = 0.006) posterior root fixation when compared to a double cinch stitch (558.0 ± 123.9 N) and (629.0 ± 110.2 N) (p = 0.178) for medial and lateral fixation, respectively. The maximum stiffness was also higher for the modified Nice knot configuration for both medial (17.1 ± 1.5 vs. 13.3 ± 1.6 N/mm) and lateral meniscus (20.0 ± 2.6 vs. 13.8 ± 2.3 N/mm), being this difference statistically significative (p = 0.001). CONCLUSIONS: The modified Nice knot allowed better adaptation in the pull-out tests and presented higher fixation strength, stiffness and reproducibility, with lower standard deviation, being at the same time economically advantageous, since only one tape is needed. LEVEL OF EVIDENCE: Level III.

6.
ACS Appl Mater Interfaces ; 16(28): 36471-36478, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-38955805

RESUMO

In the development of back electrodes for perovskite solar cells (PSCs), the major challenges are stability and cost. To address this, we present an innovative approach: Simultaneous evaporation of two independently controlled sources of metal materials was performed to achieve a uniform distribution of the alloy electrodes. In this study, Ag-Cu alloys (the molar ratio of Ag/Cu is 7/3) with a high-index crystal face (111) and a work function matching perovskite were prepared using a codeposition technique. These properties mitigate nonradiative carrier recombination at the interface and reduce the energy barrier for carrier migration. Consequently, compared to Ag based PSCs (22.77%), the implementation of Ag-Cu alloy (Ag/Cu is 7/3)-based PSCs resulted in a power conversion efficiency of 23.72%. In a 1500 h tracking test in ambient air, the Ag-Cu alloy (Ag/Cu is 7/3)-based PSCs maintained their initial efficiency of 86%. This can be attributed to almost no migration of elements from the Ag-Cu alloy electrode to the perovskite layer. Our work presents a vital strategy for improving the stability of PSCs and reducing the costs associated with the back electrode in PSCs.

7.
ACS Appl Mater Interfaces ; 16(30): 40250-40262, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39031762

RESUMO

As an essential component in wearable electronic devices and intelligent robots, flexible pressure sensors have enormous application value in fields such as healthcare, human-computer interaction, and intelligent perception. However, due to the complex and ever-changing pressure loads borne by sensors in different application scenarios, this also puts great demands on the flexible response and adjustment ability of a sensor's detection range. Therefore, developing a flexible pressure sensor with a wide and adjustable detection range, which can be applied flexibly under different pressure loads, is also a major challenge in current research. In this paper, we propose a flexible pressure sensor with a wide and adjustable detection range based on an inflatable adjustable safety airbag as the dielectric layer. This sensor uses inflatable airbags prepared using 3D printing technology and silicone reverse molding technology as the dielectric layer and achieves high sensitivity (0.6 kPa-1 to 1.19 kPa-1), wide detection range (220-1500 kPa), and flexible performance applicability by adjusting the air pressure inside the dielectric layer. At the same time, its simple production process, convenient production, fast response time (100 ms), and good stability provide the possibility for the flexible application of sensors in different pressure detection. The experimental results indicate that the sensor has enormous potential for applications in wearable devices, healthcare, human-computer interaction, and intelligent perception recognition.


Assuntos
Pressão , Dispositivos Eletrônicos Vestíveis , Humanos , Capacitância Elétrica , Impressão Tridimensional , Desenho de Equipamento
8.
Cureus ; 16(6): e62064, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38989338

RESUMO

Obesity has long been recognized as a global epidemic. One of the most effective treatments is bariatric surgery. Since the first modern procedure was reported, it has evolved over time, and multiple techniques have emerged. More than 20 years ago, one of the most widely used techniques was the non-adjustable gastric band (NAGB), which showed very promising short-term results. However, over time, it became apparent that it was not as effective in the long term. Associated gastrointestinal symptoms, such as reflux and constant vomiting, along with considerable weight regain, caused this technique to fall out of favor and be replaced by other procedures like the gastric sleeve (GS). Although the technique has fallen into disuse and is no longer recommended in the literature, there are still patients with associated complications. Few recent cases associated with these complications have been reported. Most undergo band removal, and whether to perform another procedure remains with limited evidence. We present the case of a patient who underwent an NAGB procedure 10 years ago and later experienced symptoms (reflux) and weight regain. She successfully underwent band removal and conversion to a GS at our institute in Mexico.

9.
Stud Health Technol Inform ; 315: 659-660, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-39049369

RESUMO

This study introduces the "Adjustable Oxygen Adapter," designed to address interruptions in oxygen supply for patients transitioning from oxygen spray bottles, particularly in wards with single-outlet flowmeters. Inspired by the "Three-Way Piston Rotating Adapter," this innovative design, operated by a single switch, ensures uninterrupted oxygen supply during equipment changes. Stability testing, conducted with a flow monitor by a respiratory therapist, confirms that the adapter provides a stable flow rate and oxygen concentration, offering a practical solution for seamless transitions between oxygen devices in clinical settings.


Assuntos
Desenho de Equipamento , Oxigenoterapia , Segurança do Paciente , Humanos , Oxigenoterapia/instrumentação , Oxigenoterapia/métodos , Oxigênio/administração & dosagem
10.
Bioinspir Biomim ; 19(5)2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-38986470

RESUMO

Tactile sensors play an important role when robots perform contact tasks, such as physical information collection, force or displacement control to avoid collision. For these manipulations, excessive contact may cause damage while poor contact cause information loss between the robotic end-effector and the objects. Inspired by skin structure and signal transmission method, this paper proposes a tactile sensing system based on the self-sensing soft pneumatic actuator (S-SPA) capable of providing tactile sensing capability for robots. Based on the adjustable height and compliance characteristics of the S-SPA, the contact process is safe and more tactile information can be collected. And to demonstrate the feasibility and advantage of this system, a robotic hand with S-SPAs could recognize different textures and stiffness of the objects by touching and pinching behaviours to collect physical information of the various objects under the positive work states of the S-SPA. The result shows the recognition accuracy of the fifteen texture plates reaches 99.4%, and the recognition accuracy of the four stiffness cuboids reaches 100%by training a KNN model. This safe and simple tactile sensing system with high recognition accuracies based on S-SPA shows great potential in robotic manipulations and is beneficial to applications in domestic and industrial fields.


Assuntos
Biomimética , Desenho de Equipamento , Robótica , Tato , Robótica/instrumentação , Tato/fisiologia , Biomimética/instrumentação , Humanos , Mãos/fisiologia , Materiais Biomiméticos
11.
J Ultrasound ; 2024 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-38907788

RESUMO

PURPOSE: In this retrospective, observational study we aim to compare the outcomes of the RFA treatment of benign thyroid nodules, carried out respectively with the standard fixed-needle approach (FTN) and the adjustable-tip needle technique (ATN), considered a more tailored, quicker and easier technical approach. METHODS: We enrolled 36 patients who underwent RFA treatment of symptomatic, benign, thyroid nodule, 18 with the ATN and 18 with the FTN approach, respectively. Data about absolute volume reduction, volume reduction rate (VRR) and success rate (defined as VRR ≥ 50%), after 1, 3 and 6 months of follow-up were compared. RESULTS: Our study suggested no substantial difference between the approaches, up to 6 months of follow-up, both in terms of absolute reduction (p = 0.27) and VRR (p = 0.14). These results were confirmed when the success rates, both in terms of 50%-reduction (p = 0.12) and absolute reduction (p = 0.42), was considered. Only at the 6-month evaluation, the FTN procedure showed a better success rate, yet without statistical significance (88.9% vs. 61.1%, p = 0.12). No difference emerged both in terms of patients' satisfaction and safety. CONCLUSION: Our small experience suggested no substantial difference between ATN and FTN, in terms of outcomes. On the other hand, ATN was considered to be more straightforward and could consequently allow for a shorter operator learning curve.

12.
J Clin Med ; 13(11)2024 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-38892813

RESUMO

Revisional metabolic and bariatric surgery (RMBS) presents unique challenges in addressing weight loss failure or complications arising from initial bariatric procedures. This review aims to explore the complexities and solutions associated with revisional bariatric procedures comprehensively, offering insights into the evolving terrain of metabolic and bariatric surgery. A literature review is conducted to identify pertinent studies and expert opinions regarding RMBS. Methodological approaches, patient selection criteria, surgical techniques, preoperative assessments, and postoperative management strategies are synthesized to provide a comprehensive overview of current practices and advancements in the field, including institutional protocols. This review synthesizes key findings regarding the challenges encountered in RMBS, including the underlying causes of primary procedure failure, anatomical complexities, technical considerations, and assessments of surgical outcomes. Additionally, patient outcomes, complication rates, and long-term success are presented, along with institutional approaches to patient assessment and procedure selection. This review provides valuable insights for clinicians grappling with the complexities of RMBS. A comprehensive understanding of patient selection, surgical techniques, preoperative management, and postoperative care is crucial for enhancing outcomes and ensuring patient satisfaction in the field of metabolic bariatric surgery.

13.
J Clin Med ; 13(11)2024 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-38892824

RESUMO

Background: Pulmonary vein isolation (PVI) is the standard of care for the treatment of symptomatic atrial fibrillation (AF). Novel techniques for PVI are the thermal size-adjustable cryo-balloon (CB) system and non-thermal pulsed field ablation (PFA) system. There are currently no data available for a direct comparison between these two systems. Furthermore, with new techniques, it is important to ensure a high level of efficiency and safety during treatment right from initial use. Therefore, the aim of this study was to directly compare the procedural data and safety of these two new PVI techniques in first-time users. Methods: We conducted a single-center prospective study involving 100 consecutive patients with symptomatic atrial fibrillation who underwent first-time PVI using either size-adjustable CB PVI or PFA PVI from July 2023 to March 2024. Results: Acute PVI was achieved in 100% of patients in both groups. First-pass isolation (FPI) was more frequently achieved in the PFA group compared to the size-adjustable CB group. The mean procedural duration and fluoroscopy dose were significantly shorter in the PFA cohort (p < 0.001). Furthermore, a significant reduction in fluoroscopy time was observed during the learning curve within the PFA group (p = 0.023). There were no major complications in both groups. Conclusions: Both systems demonstrate good effectiveness and safety during PVI performed by first-time users. However, the PFA group exhibited a significantly shorter procedural duration.

14.
J Clin Med ; 13(11)2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38892924

RESUMO

Objectives: Mitral valve repair is the current standard approach for mitral valve regurgitation. However, patients suffering from functional mitral regurgitation have a significant risk of recurrent regurgitation. Adjustable mitral rings may provide a solution for this adverse event. Methods: A single-center, first-in-man clinical study was performed on patients suffering from mitral valve regurgitation. Patients were implanted with the study ring and followed for six months. A balloon catheter can be inserted into the study ring frame at any time after implantation and inflated independently in the areas P1, P2, or P3, which reduces the anterior-posterior diameter. Results: Five patients (75.4 ± 6.1 years; EuroSCORE II 2.1 ± 0.9%; three female) were successfully implanted. Mechanisms of mitral regurgitation were prolapse of the P2-segment in three patients and annular dilation in two patients. Surgical implantation according to the protocol was feasible and is described herein. Median cardiopulmonary bypass time and cross clamp time were 105 (118; 195) and 94 (90; 151) min, respectively. The median intensive care unit stay was 2 (2; 3) days. No perioperative, 30-day, or 6-month mortality was observed, and the repair was stable without residual or recurrent regurgitation ≥ grade 2. All patients reached the primary endpoint without device-related morbidity. Conclusions: Successful implantation was completed in five patients without device-related adverse events. Ring implantation was safe and feasible for all patients. The opportunity of post-implant adjustment to improve leaflet coaptation is a promising new therapeutic strategy that is assessed in a phase II study.

15.
Materials (Basel) ; 17(11)2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38893827

RESUMO

Amidst the rapid advancements in the fields of photovoltaics and optoelectronic devices, CsPbBr3 nanosheets (NSs) have emerged as a focal point of research due to their exceptional optical and electronic properties. This work explores the application potential of CsPbBr3 NSs in photonic and catalytic domains. Utilizing an optimized hot-injection method and a ZnBr2-assisted in situ passivation strategy, we successfully synthesized CsPbBr3 NSs with controlled dimensions and optical characteristics. Comprehensive characterization revealed that the nucleation environment and thickness significantly influenced the structure and optical performance of the materials. The results indicate that the optimized synthesis method enables control over the lateral dimensions of the nanoparticles, ranging from 9.1 ± 0.06 nm to 334.5 ± 4.40 nm, facilitating the tuning of the excitation wavelength from 460 nm (blue) to 510 nm (green). Further analyses involving photoresponse and electrochemical impedance spectroscopy demonstrated the substantial potential of these NSs in applications such as photocatalysis and energy conversion.

16.
Sensors (Basel) ; 24(11)2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38894065

RESUMO

A 9-10-bit adjustable and energy-efficient switching scheme for SAR ADC with one-LSB common-mode voltage variation is proposed. Based on capacitor-splitting technology and common-mode conversion techniques, the proposed switching scheme reduces the DAC switching energy by 96.41% compared to the conventional scheme. The low complexity and the one-LSB common-mode voltage offset of this scheme benefit from the simultaneous switching of the reference voltages of the capacitors corresponding to the positive array and the negative array throughout the entire reference voltage switching process, and the reference voltage of each capacitor in the scheme does not change more than two voltages. The post-layout result shows that the ADC achieves the 54.96 dB SNDR, the 61.73 dB SFDR, and the 0.67 µw power consumption with the 10-bit mode and the 48.33 dB SNDR, the 54.17 dB SFDR, and the 0.47 µw power consumption with the 9-bit mode in a 180 nm process with a 100 kS/s sampling frequency.

17.
Proc Natl Acad Sci U S A ; 121(24): e2321758121, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38830093

RESUMO

Impulsivity is a personality construct frequently employed to explain and predict important human behaviors. Major inconsistencies in its definition and measurement, however, have led some researchers to call for an outright rejection of impulsivity as a psychological construct. We address this highly unsatisfactory state with a large-scale, preregistered study (N = 1,676) in which each participant completed 48 measures of impulsivity derived from 10 self-report scales and 10 behavioral tasks and reported frequencies of seven impulsivity-related behaviors (e.g., impulsive buying and social media usage); a subsample (N = 196) then completed a retest session 3 mo later. We found that correlations between self-report measures were substantially higher than those between behavioral tasks and between self-report measures and behavioral tasks. Bifactor analysis of these measures exacted one general factor of impulsivity I, akin to the general intelligence factor g, and six specific factors. Factor I was related mainly to self-report measures, had high test-retest reliability, and could predict impulsivity-related behaviors better than existing measures. We further developed a scale named the adjustable impulsivity scale (AIMS) to measure I. AIMS possesses excellent psychometric properties that are largely retained in shorter versions and could predict impulsivity-related behaviors equally well as I. These findings collectively support impulsivity as a stable, measurable, and predictive trait, indicating that it may be too early to reject it as a valid and useful psychological construct. The bifactorial structure of impulsivity and AIMS, meanwhile, significantly advance the conceptualization and measurement of construct impulsivity.


Assuntos
Comportamento Impulsivo , Humanos , Masculino , Feminino , Adulto , Autorrelato , Personalidade , Adulto Jovem , Adolescente , Reprodutibilidade dos Testes , Pessoa de Meia-Idade
18.
Ann Vasc Dis ; 17(2): 164-170, 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38919316

RESUMO

Objectives: To assess the physical features and compression characteristics of a newly developed adjustable compression garment, McBoooon (Mc). Methods: Twelve healthy volunteers were recruited to assess the compression characteristics. The interface pressure (IP) was continuously measured to calculate the static (SSI) and dynamic stiffness indices (DSI). Additionally, the peak flow velocity (PV) of the popliteal vein during ankle dorsiflexion was measured using ultrasonography. Each parameter was compared between ASHIKA stockings (AS), Mc applied at the same resting pressure as AS (Mc1), and Mc applied at a resting pressure approximately twice that of Mc1 (Mc2). Results: SSI and DSI were significantly different, increasing in the order AS < Mc1 < Mc2 (p <0.01). Although the PV was significantly higher in the compression group than in the control group (p <0.05), no significant differences were found among the three groups. Conclusion: The physical features and compression characteristics of Mc were clarified. The high stiffness of this garment improves the adherence to compression therapy and contributes to the treatment of chronic venous insufficiency.

19.
Materials (Basel) ; 17(12)2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38930208

RESUMO

Appropriate biodegradability to meet the demands of wound repair is critical for superficial wound repair membrane applications. Tyrosinase-catalyzed crosslinking SF (c-SF) membranes were constructed and regulated the degradation behavior in this study. The crosslinking degree of the c-SF membranes could be adjusted by reaction ratios of tyrosinase against SF (TYR/SF). Upon reaching a TYR/SF ratio of 20/6000, the degree of crosslinking increased to 88.17 ± 0.20%, without obvious changes in the crystal structure. The degradation behavior was regulated by the TYR/SF ratio and the degradation environment. All c-SF membranes remained stable after immersion without collagenase but showed an adjustable degradation behavior in the presence of collagenase. As the TYR/SF ratio increased, the residual weights increased from 23.31 ± 1.35% to 60.12 ± 0.82% after 7 days of degradation, occurring with low increased amounts of ß-sheet structure and free amino acids. This work provides a new c-SF membrane with controllable rapid degradability and favorable cytocompatibility, which can help to meet requirements for biodegradable superficial wound repair membranes.

20.
Sensors (Basel) ; 24(12)2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38931623

RESUMO

As a noninvasive neuromodulation technique, transcranial magnetic stimulation (TMS) has important applications both in the exploration of mental disorder causes and the treatment of mental disorders. During the stimulation, the TMS system generates the intracranial time-varying induced E-field (E-field), which alters the membrane potential of neurons and subsequently exerts neural regulatory effects. The temporal waveform of the induced E-fields is directly related to the stimulation effect. To meet the needs of scientific research on diversified stimulation waveforms and flexible adjustable stimulation parameters, a novel efficient pulse magnetic stimulation circuit (the EPMS circuit) design based on asymmetric cascaded multilevel technology is proposed in this paper. Based on the transient analysis of the discharge circuit, this circuit makes it possible to convert the physical quantity (the intracranial induced E-field) that needs to be measured after magnetic stimulation into easily analyzable electrical signals (the discharge voltage at both ends of the stimulation coil in the TMS circuit). This EPMS circuit can not only realize monophasic and biphasic cosine-shaped intracranial induced E-fields, which are widely used in the market, but also realize three types of new intracranial induced E-field stimulation waveform with optional amplitude and adjustable pulse width, including monophasic near-rectangular, biphasic near-rectangular and monophasic/biphasic ladder-shaped stimulation waveform, which breaks through the limitation of the stimulation waveform of traditional TMS systems. Among the new waveforms produced by the EPMS circuit, further research was conducted on the dynamic response characteristics of neurons under the stimulation of the biphasic four-level waveform (the BFL waveform) with controllable parameters. The relationship between TMS circuit parameters (discharge voltage level and duration) and corresponding neural response characteristics (neuron membrane potential change and neuronal polarizability ratio) was explained from a microscopic perspective. Accordingly, the biological physical quantities (neuronal membrane potential) that are difficult to measure can be transformed into easily analyzable electrical signals (the discharge voltage level and duration). Results showed that compared with monophasic and biphasic cosine induced E-fields with the same energy loss, the neuron polarization ratio is decreased by 54.5% and 87.5%, respectively, under the stimulation of BFL waveform, which could effectively enhance the neuromodulation effect and improve the stimulation selectivity.


Assuntos
Estimulação Magnética Transcraniana , Estimulação Magnética Transcraniana/métodos , Estimulação Magnética Transcraniana/instrumentação , Humanos , Neurônios/fisiologia , Animais , Desenho de Equipamento
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