Lei Wei

The functional role of glutamatergic (vGluT2) neurons in the pedunculopontine nucleus (PPN) in modulating motor activity remains controversial. Here, we demonstrated that the activity of vGluT2 neurons in the rostral PPN is correlated with locomotion and ipsilateral head-turning. Beyond these motor functions, we found that these rostral PPN-vGluT2 neurons remarkably respond to salient stimuli. Furthermore, we systematically traced the upstream and downstream projections of these neurons and identified two downstream projections from these neurons to the caudal pontine reticular nucleus/anterior gigantocellular reticular nucleus (PnC/GiA) and the zona incerta (ZI). Our findings indicate that the projections to the PnC/GiA inhibit movement, consistent with ‘pause-and-play’ behavior, whereas those to the ZI promote locomotion, and others respond to a new ‘pause-switch-play’ pattern. Collectively, these findings elucidate the multifaceted influence of the PPN on motor functions and provide a robust theoretical framework for understanding its physiological and potential therapeutic implications.

Pressures sensors based on Micro Electro Mechanical Systems (MEMS) technology have been employed for measuring the pressure inside the human body due to their small size, light weight, and low energy consumption. Hermetic packages are necessary to protect the implants from body fluid corrosion. Materials like metal and glass are usually considered to be hermetic and can ensure several years of lifetime. Materials with low permeability such as liquid crystal polymers and parylene are also supposed to be short-term hermetic when the expected lifetime is not too long (less than a year). Water penetration and interface adhesion determine whether the package fails. Helium leakage tests and water concentration tests can be used to predict when the package fails. In addition, for more short-term implantable devices (several days or weeks), bioabsorbable packages can be helpful. The main advantage is the self-degradation of the packaging material can avoid tissue damage caused by long-term implantation or infection caused by secondary removal surgery.

By eliminating the influence of the substrate on parasitic thermal resistance, MEMS suspended structures become one of the accurate nanoscale thermoelectric performance evaluation devices. However, the process of MEMS suspended thermoelectric devices is complex, and its multilayer suspended structure is easy to fracture due to large stress. As a result, optimizing the design of suspended structures is critical in order to reduce manufacturing complexity and increase yield. In this study, finite element simulation is used to investigate the impacts of varying structures and sizes on the stress of MEMS suspended devices. The maximum stress and average stress of silicon nanomaterials are lowered by 90.89% and 92.35%, respectively, by optimizing the structure and size of the beams and nanobelt. Moreover, MEMS suspended devices of various structures are successfully manufactured. It not only increases the yield to more than 70% but also decreases the impact of strain on thermoelectric performance and can be used to create suspended devices with integrated silicon microstrips.

Resonator-integrated optical gyroscopes have advantages such as all-solid-state, on-chip integration, miniaturized structure, and high precision. However, many factors deteriorate the performance and push it far from the shot-noise limited theoretical sensitivity. This paper reviews the mechanisms of various noises and their corresponding suppression methods in resonator-integrated optical gyroscopes, including the backscattering, the back-reflection, the polarization error, the Kerr effect, and the laser frequency noise. Several main noise suppression methods are comprehensively expounded through inductive comparison and reasonable collation. The new noise suppression technology and digital signal processing system are also addressed.

MEMS/NEMS resonators are widely studied in biological detection, physical sensing, and quantum coupling. This paper reviews the latest research progress of MEMS/NEMS resonators with different structures. The resonance performance, new test method, and manufacturing process of single or double-clamped resonators, and their applications in mass sensing, micromechanical thermal analysis, quantum detection, and oscillators are introduced in detail. The material properties, resonance mode, and application in different fields such as gyroscope of the hemispherical structure, microdisk structure, drum resonator are reviewed. Furthermore, the working principles and sensing methods of the surface acoustic wave and bulk acoustic wave resonators and their new applications such as humidity sensing and fast spin control are discussed. The structure and resonance performance of tuning forks are summarized. This article aims to classify resonators according to different structures and summarize the working principles, resonance performance, and applications.

Thermoelectric technology can achieve mutual conversion between thermoelectricity and has the unique advantages of quiet operation, zero emissions and long life, all of which can help overcome the energy crisis. However, the large-scale application of thermoelectric technology is limited by its lower thermoelectric performance factor (ZT). The thermoelectric performance factor is a function of the Seebeck coefficient, electrical conductivity, thermal conductivity and absolute temperature. Since these parameters are interdependent, increasing the ZT value has always been a challenge. Here, we report the growth of Cu₂Se thin films with a thickness of around 100 nm by magnetron sputtering. XRD and TEM analysis shows that the film is low-temperature α-Cu₂Se, XPS analysis shows that about 10% of the film’s surface is oxidized, and the ratio of copper to selenium is 2.26:1. In the range of 300–400 K, the maximum conductivity of the film is 4.55 × 10⁵ S m⁻¹, which is the maximum value reached by the current Cu₂Se film. The corresponding Seebeck coefficient is between 15 and 30 µV K⁻¹, and the maximum ZT value is 0.073. This work systematically studies the characterization of thin films and the measurement of thermoelectric properties and lays the foundation for further research on nano-thin-film thermoelectrics.