A Miniature Traveling Wave Ultrasonic Linear Motor Utilizing Bimorph Transducers.

Scaling down linear actuators is crucial for various industrial applications, yet the efficiency of electromagnetic linear actuators decreases significantly as they are miniaturized. Millimeter-scale miniature ultrasonic motors, on the other hand, maintain high efficiency. This paper describes a new approach to facilitate the miniaturization of traveling wave linear ultrasonic motors by attaching bimorph transducers to the ends of the stator beams. To control the resonance frequency and facilitate the generation of a traveling flexural wave in the beam, grooves are incorporated into the bimorph structure. Mechanical output is improved by amplifying the transverse displacement through the addition of teeth to the beam. Utilizing the Finite Element Method (FEM), a prototype measuring 10 mm × 10 mm × 160 mm was designed, fabricated, and tested. It achieved an output speed of 53.7 mm/s and a thrust of 0.83 N at a peak-to-peak voltage of 300 V and a frequency of 32.7 kHz. The results show that the proposed ultrasonic linear motors with small size, simple structure and overall compactness have promising applications in robotics, precision machining, medical equipment and other fields requiring miniature compact linear motions.

Recent advances in the authentication (geographical origins, varieties and aging time) of tangerine peel (Citri reticulatae pericarpium): A review.

The consumption of tangerine peel (Citri reticulatae pericarpium, CRP) has been steadily increasing worldwide due to its proven health benefits and sensory characteristics. However, the price of CRP varies widely based on its origin, variety, and aging time, which has led many manufacturers to offer inferior products by exploiting the sensory similarity of CRP, seriously undermining consumers' interests. Therefore, it is essential to identify the authenticity of the CRP. In this study, the research progress on the authenticity of CRP from different origins, years and varieties over the past 10 years and the application and prospects of the main technologies and techniques were reviewed. The advantages and disadvantages of the commonly used methods were also summarized and compared. Mass spectrometry-based and spectroscopy-based techniques are the most commonly used methods for analyzing CRP authenticity. However, designing fast, non-destructive and green methods for identifying CRP authenticity would be the future trend.

Intravascular Optical Coherence Tomography Utilizing a Miniature Piezoelectric-Driven Probe.

Intravascular optical coherence tomography (IV-OCT) is crucial for evaluating lumen dimensions and guiding interventional procedures. However, traditional catheter-based IV-OCT faces challenges in achieving precise and full-field 360° imaging in tortuous vessels. Current IV-OCT catheters that employ proximal actuators and torque coils are susceptible to non-uniform rotational distortion (NURD) in tortuous vessels, while distal micromotor-driven catheters struggle with complete 360° imaging due to wiring artifacts. In this study, we developed a miniature optical scanning probe with an integrated piezoelectric-driven fiber optic slip ring (FOSR) to facilitate smooth navigation and precise imaging within tortuous vessels. The FOSR features a coil spring-wrapped optical lens serving as a rotor, enabling efficient 360° optical scanning. The structurally-and-functionally-integrated design significantly streamlines the probe (with a diameter of 0.85 mm and a length of 7 mm) while maintaining an excellent rotational speed of 10,000 rpm. High-precision 3D printing technology ensures accurate optical alignment of the fiber and lens inside the FOSR, with a maximum insertion loss variation of 2.67 dB during probe rotation. Finally, a vascular model demonstrated smooth probe insertion into the carotid artery, and imaging of oak leaf, metal rod phantoms, and ex vivo porcine vessels verified its capabilities for precise optical scanning, comprehensive 360° imaging, and artifact elimination. The FOSR probe exhibits small size, rapid rotation, and optical precision scanning, rendering it exceptionally promising for cutting-edge intravascular optical imaging techniques.

Entrepreneurial role models and college students' entrepreneurial calling: A moderated mediation model.

Introduction: College entrepreneurship education should not only cultivate a group of college students who have strong willingness to start a business immediately after graduation, but also pay attention to future entrepreneurship success of college students. Correspondingly, in addition to attaching importance to improving college students' entrepreneurial intention, college entrepreneurship education should pay attention to improving college students' entrepreneurial calling. At present, there is insufficient research on the association between entrepreneurial role models and entrepreneurial calling. We aim to study the mechanism and boundary condition of the association between entrepreneurial role models and entrepreneurial calling. Methods: A longitudinal survey was distributed among 519 students from 16 colleges and universities in China. In the survey, the college students answered questions on entrepreneurial role models, entrepreneurial calling, entrepreneurial perceived behavioral control and entrepreneurial hands-on practice. Hierarchical regression was conducted, testing the association between entrepreneurial role models and entrepreneurial calling of college students, mediated by entrepreneurial perceived behavioral control and moderated by entrepreneurial hands-on practice. Results: Therefore, based on the social learning theory, the theory of planned behavior and the entrepreneurial event model, and by hierarchical regression of the data, this study confirmed that entrepreneurial role models were positively associated with college students' entrepreneurial calling by partially mediating with entrepreneurial perceived behavioral control. Moreover, Entrepreneurial hands-on practice positively moderated not only the relationship between entrepreneurial perceived behavioral control and entrepreneurial calling, but also the mediating association of entrepreneurial perceived behavioral control between entrepreneurial role models and entrepreneurial calling. Discussion: This study not only enriches the theoretical research on entrepreneurial calling and entrepreneurial role models, but also provides valuable educational enlightenment for colleges and universities to improve the students' entrepreneurial calling.

Structural Design and Experimental Studies of Resonant Fiber Optic Scanner Driven by Co-Fired Multilayer Piezoelectric Ceramics.

Piezo-driven resonant fiber optic scanners are gaining more and more attention due to their simple structure, weak electromagnetic radiation, and non-friction loss. Conventional piezo-driven resonant fiber optic scanners typically use quadrature piezoelectric tubes (piezo tubes) operating in 31-mode with high drive voltage and low excitation efficiency. In order to solve the abovementioned problem, a resonant fiber scanner driven by co-fired multilayer piezoelectric ceramics (CMPCs) is proposed in which four CMPCs drive a cantilevered fiber optic in the first-order bending mode to achieve efficient and fast space-filling scanning. In this paper, the cantilever beam vibration model with base displacement excitation was derived to provide a theoretical basis for the design of the fiber optic scanner. The finite element method was used to guide the dynamic design of the scanner. Finally, the dynamics characteristics and scanning trajectory of the prepared scanner prototype were tested and compared with the theoretical and simulation calculation results. Experimental results showed that the scanner can achieve three types of space-filling scanning: spiral, Lissajous, and propeller. Compared with the structure using piezo tubes, the designed scanner achieved the same scanning range with smaller axial dimensions, lower drive voltage, and higher efficiency. The scanner can achieve a free end displacement of 10 mm in both horizontal and vertical directions under a sinusoidal excitation signal of 50 Vp-p and 200 Hz. The theoretical, simulation and experimental results validate the feasibility of the proposed scanner structure and provide new ideas for the design of resonant fiber optic scanners.

A Single Oscillator-Excited Piezoelectric Actuator with Internal Contact Teeth.

The tail rotor of a helicopter, a crucial component, traditionally relies on a complex drive mode involving reducers and transmission gears. This conventional setup, with its lengthy transmission chain and numerous components, hinders miniaturization efforts. In response to this challenge, our paper presents a novel piezoelectric drive approach. Our objective was to suggest an innovative design capable of minimizing the components involved in the tail rotor drive. This design can be adjusted in size according to specific requirements and is effective up to a specified speed. Moreover, it facilitates the process of miniaturization and integration. The piezoelectric actuator's stator comprises an ultrasonic amplitude transformer, a ring, and three drive teeth. Utilizing the rod-like structure of the tail brace, the actuator is simplified by adhering ceramic sheets to it. The rotary piezoelectric actuator combines the first longitudinal mode of a rod with torus bending modes. The drive teeth then amplify the ring's displacement, facilitating rotor rotation. The resonant frequency and modal shape of the actuator were determined using the finite element method. Furthermore, an investigation was conducted to analyze the influence of the drive teeth positioning on the motion trajectory at the contact point. Theoretically, we infer that the declination angle of the drive tooth is a crucial parameter for achieving high speeds. To test our idea, we built three prototype stators with different drive tooth declination angles. Our actuator stands out for its cost-effectiveness, structural simplicity, compatibility with harmonic signals, and ease of miniaturization. It can be considered for the drive of the tail rotor of a microhelicopter.

A Low-Voltage Cylindrical Traveling Wave Ultrasonic Motor Incorporating Multilayered Piezoelectric Ceramics.

In-plane bending traveling wave ultrasonic motors (USM), which are compact in structure and flexible in design, have been widely applied in biological engineering, optical engineering, and aerospace engineering. However, the high driving voltage and complicated driving circuit of this kind of USM restrict their further miniaturization and electromechanical integration in these applications and bring some potential safety hazards. To solve this problem, a low-voltage-driving traveling wave USM incorporating cofired multilayer piezoelectric ceramics was proposed in this work. Four cofired piezoelectric ceramics were strategically designed to excite two orthogonal third-order in-plane bending modes with the same frequency of the USM. The principles of traveling wave synthesis and low-voltage-driving of the USM were deduced, and the stator dynamic design and transient dynamic simulation were carried out by finite-element method. The microproperties of cofired piezoelectric multilayer ceramics, the vibration characteristics of the stator, and the mechanical output performance of the USM were tested by experiments. The results indicated that the motor can work as low as 5 [Formula: see text]. A long stroke with a maximum forward and reverse rotational speeds of 187.7 and 176.6 r/min were obtained, respectively, and a maximum stalling torque of 4.8 mN · m at 47.3 kHz under 15 [Formula: see text] was achieved. The results showed that the proposed USM is small, low in driving voltage, and high in torque output, which has promising applications in aerospace, biomedicine, and other fields that require a lightweight and integration of driving devices.

3-D High Frequency Ultrasound Imaging by Piezo-Driving a Single-Element Transducer.

Electronic scanning of two-dimensional (2-D) arrays and mechanical or freehand scanning of one-dimensional (1-D) arrays have been mostly utilized for conventional three-dimensional (3-D) ultrasound (US) imaging. However, the development of 2-D arrays and the hardware systems are complicated and expensive, while freehand systems with positioning sensors and mechanical systems are mostly bulky. This article represents a novel scanning strategy for achieving high-quality 3-D US imaging with a high-frequency single-element transducer. A 42-MHz US transducer with a compact structure was designed and fabricated, which was excited in the 2-D vibration by a tubular piezoelectric actuator. A dedicated imaging system was set up and both B-mode and 3-D US imaging of a custom wire phantom have been carried out to evaluate the performance of the proposed transducer. Compared to the results obtained with the motorized linear translation stage, the reconstructed images obtained by the proposed resonance scanning method are accurate, demonstrating the feasibility of 3-D US imaging with a vibrating single-element US transducer.

Three-Dimensional Intravascular Ultrasound Imaging Using a Miniature Helical Ultrasonic Motor.

Existing 3-D intravascular ultrasound (IVUS) systems that combine two electromagnetic (EM) motors to drive catheters are bulky and require considerable efforts to eliminate EM interference (EMI). Here, we propose a new scanning method to realize 3-D IVUS imaging using a helical ultrasonic motor to overcome the aforementioned issues. The ultrasonic motor with compact dimensions (7-mm outer diameter and 30-mm longitudinal length), lightweight (20.5 g), and free of EMI exhibits a great application potential in mobile imaging devices. In particular, it can simultaneously perform rotary and linear motions, facilitating precise 3-D scanning of an imaging catheter. Experimental results show that the signal-to-noise ratio (SNR) of raw images obtained using the ultrasonic motor is 5.3 dB better than that of an EM motor. Moreover, the proposed imaging device exhibits the maximum rotary speed of 12.3 r/s and the positioning accuracy of 2.6 [Formula: see text] at a driving voltage of 240 Vp-p. The 3-D wire phantom imaging and 3-D tube phantom imaging are performed to evaluate the performance of the imaging device. Finally, the in vitro imaging of a porcine coronary artery demonstrates that the layered architecture of the vessel can be precisely identified while significantly increasing the SNR of the raw images.

An insight into the flexible drive mechanism in short cylinder ultrasonic piezoelectric vibrator.

In this study, a resonant type piezoelectric vibrator for driving a flexible body is proposed and its driving principle is discussed. The flexible body driven in this article is rigid in the longitudinal direction and flexible in the transverse direction, such as in metal straps and metal wires. The exciting signals used in the piezoelectric transducer in the horizontal and vertical directions are both sinusoidal signals, possessing a phase shift of π/2. Two third-order orthogonal bending in-plane modes of the same frequency were effectively excited, and an elliptic motion formed on the end plane of the vibrator toothed structure. A flexible body was then effectively driven by friction under a certain amount of tension. The proposed vibrator was designed using the finite element method, and the flexible drive models were established, while the output force in the contact friction was analyzed. The vibration characteristics of the vibrator were tested in order to obtain the resonance frequencies and responses. An experimental system was then established to test the mechanical output characteristics. The results demonstrate that the difference in thickness, tension force, and surface roughness between the flexible bodies confer great influence on driving. With a thickness of 0.01 mm, 0.02 mm, and 0.03 mm, the flexible metal strap velocity was found to be 24 mm/s, 43.64 mm/s, and 10.43 mm/s under the corresponding proper tension, smooth surface, and voltage of 200Vp-p, respectively.