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The efficiency and repeatability of capacitively coupled plasma (CCP) processes are highly dependent on achieving precise impedance matching between the plasma load and the RF power supply. This paper presents a numerical investigation of the role of frequency modulation in enhancing impedance matching of RF CCPs, a technique that can be critical to maintaining operational efficiency and plasma stability. Through a detailed simulation approach, the research explores how variations in the driving frequency impact plasma characteristics and electrical parameters, particularly focusing on the CCP's impedance behavior. The simulations demonstrate that when impedance matching is achieved at a fixed fundamental frequency of 13.56 MHz, changes in driving frequency will lead to reduced power coupling efficiency and increased reflection. The study introduces a frequency modulation strategy that allows us to re-establish high-quality impedance matching after changes of the plasma impedance occur, e.g., due to changes of the variable capacitor settings inside the matchbox or gas pressure, thereby improving the CCP's performance. As the driving frequency can be adjusted electrically, adjusting the impedance matching by frequency modulation is much faster than based on mechanical adjustments of variable capacitors inside the matching and could, thus, allows quicker matching. The findings underscore the impact of frequency modulation on power absorption efficiency and highlight the sensitivity of impedance matching to driving frequency fluctuations. This study provides a foundation for further exploration into the optimization of RF CCP systems with the potential to enhance process control and plasma performance across a range of industrial applications, especially pulsed CCPs. [ABSTRACT FROM AUTHOR]

Objectives: To reveal the force profiles recorded by haptic autonomous robotic force feedback during the transcrestal sinus floor elevation (TSFE) process, providing a reference for the surgery strategy during TSFE. Materials and methods: A total of 42 maxillary sinus models with different angles of the sinus floor (30°, 40°, 50°, 60°, 70°, 80°, and 90°, compared to vertical plane) were 3D printed. Implant site preparation was performed using a robotic system, and the total force (Ft) and axial force along the drill (Fz) during the surgery were recorded by the haptic robotic arm. The actual initial breakthrough point (drill contacting sinus floor) and complete breakthrough point (drill penetrating the sinus floor) were defined visually (the actual IBP and the actual CBP). The theoretical initial breakthrough point (the theoretical IBP) and the theoretical complete breakthrough point (the theoretical CBP) defined by the robot‐guided system and the CBCT were determined by real‐time force feedback and imaging distance measurement, respectively. The distance from the bottom of the resin model to the actual IBP and the actual CBP was defined as Di and Dt, respectively. Results: The difference in Fz began to increase significantly at 70°, while the difference in Ft became significant at 60°. When the angle was greater than 70°, there was no significant difference in the discrepancy between the actual and theoretical perforation points. Compared to judging the breakthrough point by CBCT, real‐time force feedback TSFE under robotic surgery achieved more accurate initial breakthrough point detection. Conclusions: The smaller the angle, the larger the breakthrough force for the drill. The real‐time force feedback of haptic robotic system during TSFE could provide reliable reference for dentists. More clinical studies are needed to further validate the application of robotic surgery assisted TSFE. [ABSTRACT FROM AUTHOR]

Capacitively coupled plasmas (CCPs) are widely used in plasma processing applications, where efficient power coupling between the radio frequency (RF) source and the plasma is crucial. In practical CCP systems, impedance matching networks (IMNs) are employed to minimize power reflection. However, the presence of coaxial cables can significantly impact plasma impedance and matching performance. We develop a comprehensive simulation framework for the IMN design of CCPs, fully considering the effects of RF coaxial cables. The model self-consistently couples a distributed transmission line (TL) model, a lumped-element circuit model, and an electrostatic particle-in-cell model. This coupled model is used to investigate the impact of coaxial cables on matching performance under various discharge conditions and cable configurations. The simulation results indicate that the optimal power transmission efficiency was achieved after 6 matching iterations. The power coupled to the CCP increased from 2.7 W before matching to 180.9 W, and the reflection coefficient ultimately decreased to 0.003. The results also reveal that neglecting the cables will lead to a decrease in the power dissipated in the CCP. The proposed method demonstrates effectiveness in achieving impedance matching for different gas pressures (75–300 mTorr) and cable lengths. It can be concluded that the matching speed is faster for an appropriate cable length. This work provides valuable insights into the role of TLs in CCP impedance matching and offers a practical tool for optimizing power delivery in realistic CCP systems with RF coaxial cables. [ABSTRACT FROM AUTHOR]

This paper establishes a fully self‐consistent coupled model of fluid and external circuits. The Kirchhoff equation, the charge conservation equation, and Poisson equation are coupled via boundary conditions and integrated into the fluid model for iterative parameter solution. On the basis of this model, we investigate the influence of impedance matching on single‐frequency capacitively coupled plasma characteristics under different parameters and topological structures. The findings suggest that after several iterations the matching parameters converge. Using different initial circuit parameters, the adjustable capacitance and inductance are eventually adjusted to approximately equal values, resulting in the same optimal matching state, whereas diverse discharge parameters led to different outcomes. Under fixed parameters for two topologies, the power absorption efficiency increases, and the reflection coefficient approaches zero, and the best matching is found. This model can be extended to different fluid programs to investigate the impact of complex external circuits with impedance matching network on plasma discharge while simultaneously seeking best impedance matching. [ABSTRACT FROM AUTHOR]

Impedance matching can maximize the absorbed power transferred to the plasma load and minimize the reflected power, making it critical and indispensable for capacitively coupled plasmas (CCPs). The external circuit usually interacts with the plasma nonlinearly, so the global simulation of the external circuit and plasma and the matching design is very challenging. In this work, an a priori model was proposed to match the plasma impedance and the external circuit impedance for single-frequency CCPs. By calculating the plasma impedance and the matching network, the matching parameters were iteratively updated to find the best matching parameters. By adjusting the capacitance and the inductance of the circuit by numerical simulations, the reflection coefficient can be significantly reduced. At the same time, the plasma power absorption efficiency will be significantly improved. The universality of the method was demonstrated by choosing different initial circuit, discharge, and plasma parameters. The proposed method provides an effective matching design reference for CCPs. [ABSTRACT FROM AUTHOR]

The breakdown process of capacitively coupled plasma (CCP) in the presence of a matching network is rarely studied, even though it is the indispensable part of the most laboratory and industrial devices of CCP. Based on the method of Verboncoeur, the solution method of the general "L"-type match circuit coupled with a particle-in-cell/Monte Carlo code is deduced self-consistently. Based on this method, the electrical breakdown process of CCP is studied. Both the plasma parameters and the electric parameters of the matching network during the breakdown are given and analyzed. In the pre-breakdown phase, the entire circuit can be considered as a linear system. However, the formation of the sheath during breakdown significantly enhanced the capacitance of the discharge chamber, which changed the electric signal amplitude of the external circuit. With the stabilization of plasma, the equivalent capacitance of CCP increases, which continues to change the electrical signal until the steady-state is reached. Accompanied by plasma stabilization is the appearance of high-order harmonics of discharge current caused by the gradually oscillating CCP capacitance. The breakdown characteristics can be obviously affected by the capacitance of the matching network. In the case of a breakdown zone, some breakdowns with special characteristics can be obtained by choosing the different capacitors. These works might be a reference for understanding the interaction between the plasma and the external circuit during the breakdown process and how to modulate the gas breakdown by controlling the external circuit. [ABSTRACT FROM AUTHOR]

Impedance matching plays a critical role in achieving stable and controllable plasma conditions in capacitive coupled plasma (CCP) systems. However, due to the complex circuit system, the nonlinear relationships between components, and the extensive parameter space of the matching network, finding optimal component values pose significant challenges. To address this, we employ an artificial neural network as a surrogate model for the matching system, leveraging its powerful pattern learning capability for a reliable and efficient search for matching parameters. In this paper, we designed four different parameters as optimization objectives and took the modulus of the reflection coefficient as an example to demonstrate the impedance matching optimization process of a CCP in detail using a particle-in-cell/Monte Carlo collision model. Our approach not only provides an effective optimization direction but also furnishes an entire parameter space that aligns with expectations, rather than just a single point. Moreover, the method presented in this paper is applicable to both numerical simulations and experimental matching parameter optimization. [ABSTRACT FROM AUTHOR]

Swarming magnetic micro/nanorobots hold great promise for biomedical applications, but at present suffer from inferior capabilities to perceive and respond to chemical signals in local microenvironments. Here we demonstrate swarming magnetic photonic‐crystal microrobots (PC‐bots) capable of spontaneously performing on‐the‐fly visual pH detection and self‐regulated drug delivery by perceiving local pH changes. The magnetic PC‐bots consist of pH‐responsive hydrogel microspheres with encapsulated one‐dimensional periodic assemblies of Fe3O4 nanoparticles. By programming external rotating magnetic fields, they can self‐organize into large swarms with much‐enhanced collective velocity to actively find targets while shining bright "blinking" structural colors. When approaching the target with abnormal pH conditions (e.g., an ulcerated superficial tumor lesion), the PC‐bots can visualize local pH changes on the fly via pH‐responsive structural colors, and realize self‐regulated release of the loaded drugs by recognizing local pH. This work facilitates the development of intelligent micro/nanorobots for active "motile‐targeting" tumor diagnosis and treatment. [ABSTRACT FROM AUTHOR]