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Cavitation theory for ultrasonic vibration. (A) Schematic of the cavitation process, (i,ii) process of growth and collapse of bubbles, (iii) supporting structures will be removed. (B) Effect of ultrasonic frequency ( f a ) on the maximum radius of the bubble. (C) Effect of f a on the pressure outside the bubble (p out ). (D) Total kinetic energy (K) of gas in a bubble during the cavitation process. (E) Value of shock wave (p) when the bubble collapses.
Source publication
Complex three-dimensional (3D) microstructures are attracting more and more attention in many applications such as microelectromechanical systems, biomedical engineering, new materials, new energy, environmental protection, and wearable electronics. However, fabricating complex 3D microstructures by 3D printing techniques, especially those with lon...
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... cavitation theory for ultrasonic vibration was proposed in previous studies, 43,44 which is used to explain the results in the present investigation. It is demonstrated in Figure 3A-i that there are many tiny bubbles at the interface of the liquid and the solid structures first. Then, these tiny bubbles quickly grow up at the negative pressure zones because of the ultrasound waves ( Figure 3A-i), and they will collapse at the positive pressure zones with the longitudinal spread of ultrasound waves ( Figure 3A-ii). ...
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... is demonstrated in Figure 3A-i that there are many tiny bubbles at the interface of the liquid and the solid structures first. Then, these tiny bubbles quickly grow up at the negative pressure zones because of the ultrasound waves ( Figure 3A-i), and they will collapse at the positive pressure zones with the longitudinal spread of ultrasound waves ( Figure 3A-ii). Therefore, bubbles are compressed and stretched alternately under positive and negative pressures from the ultrasonic vibration. ...
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... is demonstrated in Figure 3A-i that there are many tiny bubbles at the interface of the liquid and the solid structures first. Then, these tiny bubbles quickly grow up at the negative pressure zones because of the ultrasound waves ( Figure 3A-i), and they will collapse at the positive pressure zones with the longitudinal spread of ultrasound waves ( Figure 3A-ii). Therefore, bubbles are compressed and stretched alternately under positive and negative pressures from the ultrasonic vibration. ...
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... bubbles are compressed and stretched alternately under positive and negative pressures from the ultrasonic vibration. The huge pressure change at the surface of the supporting structures will break them up ( Figure 3A-iii). The supporting structures will be almost completely removed after ultrasonic treatment for tens of seconds. ...
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... supporting structures will be almost completely removed after ultrasonic treatment for tens of seconds. Based on the cavitation theory (Supporting Information S3), it can be found that there are several cavitation bubbles generated during a single cycle; the maximum radius of the bubble decreases with the increase of the ultrasonic frequency (f a ) ( Figure 3B). The value of pressure outside the bubble, p out , during the cavitation process is shown in Figure 3C. ...
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... on the cavitation theory (Supporting Information S3), it can be found that there are several cavitation bubbles generated during a single cycle; the maximum radius of the bubble decreases with the increase of the ultrasonic frequency (f a ) ( Figure 3B). The value of pressure outside the bubble, p out , during the cavitation process is shown in Figure 3C. It can be found that p out decreases with the increase of f a . ...
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... a is 40 kHz for the present ultrasonic machine. Meanwhile, the effect of sound pressure amplitude, p a , on the cavitation process is analyzed ( Figure S3). The total kinetic energy (K) of gas in a bubble changes sharply with the growth and collapse of bubbles ( Figure 3D). ...
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... the effect of sound pressure amplitude, p a , on the cavitation process is analyzed ( Figure S3). The total kinetic energy (K) of gas in a bubble changes sharply with the growth and collapse of bubbles ( Figure 3D). When bubbles are broken down after the compression, it will produce a tremendous pressure drop instantaneously ( Figure 3E); such a vast pressure variation will certainly produce violent destruction of the supporting structures. ...
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... total kinetic energy (K) of gas in a bubble changes sharply with the growth and collapse of bubbles ( Figure 3D). When bubbles are broken down after the compression, it will produce a tremendous pressure drop instantaneously ( Figure 3E); such a vast pressure variation will certainly produce violent destruction of the supporting structures. Besides, it could be demonstrated that the value of p decreased with the increase of the distance to the bubble center as shown in Figure 3E. ...
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... bubbles are broken down after the compression, it will produce a tremendous pressure drop instantaneously ( Figure 3E); such a vast pressure variation will certainly produce violent destruction of the supporting structures. Besides, it could be demonstrated that the value of p decreased with the increase of the distance to the bubble center as shown in Figure 3E. ...
Citations
... Contrary to traditional fabrication techniques, which primarily depend on removing materials using techniques like cutting or drilling (subtractive processes), 3DP procedures are bottom-up manufacturing techniques that rely on the gradual addition of material layers [58]. Complex 3D structures can be created more quickly and easily with 3DP than with traditional manufacturing techniques [59]. Several significant categories of 3DP technology have been designed and are frequently used: (1) materials extrusion, (2) vat photopolymerization (VPP), (3) powder bed fusion, (4) materials jetting, and (5) laminated object 3DP processes [60][61][62][63][64]. ...
Electrochemical energy storage (EES) systems like batteries and supercapacitors are becoming the key power sources for attempts to change the energy dependency from inadequate fossil fuels to sustainable and renewable resources. Electrochemical energy storage devices (EESDs) operate efficiently as a result of the construction and assemblage of electrodes and electrolytes with appropriate structures and effective materials. Conventional manufacturing procedures have restrictions on regulating the morphology and architecture of the electrodes, which would influence the performance of the devices. 3D printing (3DP) is an advanced manufacturing technology combining computer-aided design and has been recognised as an artistic method of fabricating different fragments of energy storage devices with its ability to precisely control the geometry, porosity, and morphology with improved specific energy and power densities. The capacity to create mathematically challenging shape or configuration designs and high-aspect-ratio 3D architectures makes 3D printing technology unique in its benefits. Nevertheless, the control settings, interactive manufacturing processes, and protracted post-treatments will affect the reproducibility of the printed components. More intelligent software, sophisticated control systems, high-grade industrial equipment, and post-treatment-free methods are necessary to develop. 3D printed (3DPd) EESDs necessitate dynamic printable materials and composites that are influenced by performance criteria and fundamental electrochemistry. Herein, we review the recent advances in 3DPd electrodes for EES applications. The emphasis is on printable material synthesis, 3DP techniques, and the electrochemical performance of printed electrodes. For the fabrication of electrodes, we concentrate on major 3DP technologies such as direct ink writing (DIW), inkjet printing (IJP), fused deposition modelling (FDM), and stereolithography 3DP (SLA). The benefits and drawbacks of each 3DP technology are extensively discussed. We provide an outlook on the integration of synthesis of emerging nanomaterials and fabrication of complex structures from micro to macroscale to construct highly effective electrodes for the EESDs.
... Recently, 3D printing technologies have been used, because their fabrication accuracy has improved significantly, such that microscale mechanical devices can be achieved [21][22][23][24][25]. Moreover, 3D printing enables the fabrication of more complex structures than MEMS processes, with an easy and reproducible process. ...
Ground reaction force (GRF) is a significant factor for the evaluation of animal locomotion. Recently, micro force plates have been implemented as the GRF measurement method for tiny insects. Previous micro force plates were highly sensitive but fragile and laborious to fabricate because of the use of strain-sensing elements. Here, we applied high-resolution 3D printing and a noncontact displacement meter to a micro force plate for a fruit fly. A force plate structure with 3D supporting microsprings is fabricated with easy and reproducible micro 3D printing, enabling both high sensitivity and toughness. By detecting the displacement of the plate centre externally, the vertical GRF when a fruit fly lands on the plate surface is calculated via the spring constant as the whole device. The spring constant of the microspring is designed to be approximately 5.98 N/m so that a high-resolution external laser displacement meter realizes a force resolution less than 1/50 of the body weight of a fruit fly. Providing that the four springs have the same spring constant and the displacement meter aligns at the plate centre, there is no positional error when converting from displacement to force in principle. However, the fabrication error leads to the spring constant difference. Here, we theoretically and experimentally determined the measurement point of the distance sensor where the positional error caused by the difference in spring constant of the four microsprings is compensated. It was confirmed that the calibration process improved the position error to be within ±1.5% in the experiment. Finally, we demonstrated the GRF measurement of a fruit fly. The average GRF was 6.5 μN, which was equal to the weight of a fruit fly. Our proposed device can help evaluate the biomechanics of tiny insects.
... 3D printing techniques, also known as additive manufacturing, opens a new gate for the fabrication of complex hydrogel patterns with different desirable properties [23,24]. With the fast development in 3D printing techniques, various 3D printing methods including stereolithography [25], extrusion 3D printing [26], and digital light processing lithography [27] have been applied to create complex hydrogel patterns due to their merits of design flexibility, low cost, time efficiency, and high precision [28]. ...
Smart windows with tunable optical properties in response to external environments are being developed to reduce energy consumption of buildings. In the present study, we introduce a new type of 3D printed hydrogel with amazing flexibility and stretchability (as large as 1500%), as well as tunable optical performance controlled by surrounding temperatures. The hydrogel on a PDMS substrate shows transparent-opaque transition with high solar modulation ( ΔT sol ) up to 79.332% around its lower critical solution temperature (LCST) while maintaining a high luminous transmittance ( T lum ) of 85.847% at room temperature. In addition, selective transparent-opaque transition above LCST can be achieved by patterned hydrogels which are precisely fabricated via projection micro-stereolithography (P μ SL) based 3D printing technique. Our hydrogel promises great potential applications for next generation of soft smart windows.
... Furthermore, light curing 3D printing has been widely utilized in the synthesis processes of resin, hydrogel, etc [28,29]. Patterned ultra-violet (UV) light can convert the hydrogel precursor solution into a solid layer through photo-polymerization, which can fabricate complex 3D structures made of hydrogels at the microscale with high resolution, high precision, and low cost [30]. 3D printing technique has been widely used to fabricate microfluidic chips, bionic structures, and microrobots [31,32]. ...
Hydrogels with stimuli-responsive capabilities are gaining more and more attention nowadays with prospective applications in biomedical engineering, bioelectronics, microrobot, etc. We develop a photothermal responsive hydrogel based on N-isopropylacrylamide that achieved a fast and reversible deformation manipulated only by near-infrared (NIR) light. The hydrogel was fabricated by the projection micro stereolithography based 3D printing technique, which can rapidly prototype complex 3D structures. Furthermore, with the variation of the grayscale while manufacturing the hydrogel, the deformation of the hydrogel structure can be freely tuned within a few seconds by losing and absorbing water through adjusting the intensity and the irradiation direction of the NIR light, showing a potential application in ultra-fast object grabbing and transportation. The present study provides a new method for designing ultrafast photothermal responsive hydrogel based microrobot working in water.
Functionally graded materials (FGMs) have spatial variations in structure or composition that result in gradients in their mechanical, thermal, swelling, or other properties. FGMs have garnered significant research interest because of their extensive applications in areas such as biomedical implants, sensors, and soft robotics. Recently, grayscale photopolymerization 3D printing has emerged as a promising technology for crafting complex and high‐resolution FGMs. This comprehensive work delves into various grayscale photopolymerization 3D printing techniques, offering insights into their ability to precisely control printing exposure energy and polymerization degree, which in turn influence material properties. Furthermore, this work highlights diverse applications of grayscale vat‐photopolymerization 3D printing. Finally, it offers perspectives on ways to enhance grayscale photopolymerization 3D printing, with a focus on improving printing feedstocks and grayscale strategies.
Microfluidic devices are composed of microchannels with a diameter ranging in ten to a few hundred micrometers. Thus, quite small (10-9 to 10-18 litres) amount of liquid can be manipulated by such a precise system. In the past three decades, significant progresses in materials, microfabrication, and various applications have boosted the development of promising functional microfluidic devices. In this review, the recent progresses on novel microfluidic devices with various functions and applications are presented. First, the theory and numerical methods for studying the performance of microfluidic devices are briefly introduced. Then, materials, and fabrication methods of functional microfluidic devices are summarized. Next, from the viewpoint of the applications of the microfluidic devices, the recent significant advances in heat sink, clean water production, chemical reactions, sensor, biomedical field, capillaric circuits, flexible and wearable electronic devices, microrobotics, etc., in turns are then highlighted. Finally, personal perspectives on the challenges and future developments of functional microfluidic devices, aiming to motivate researchers from the fields of engineering, materials, chemistry, mathematics, physics, etc. working together to promote further development and applications of functional microfluidic devices, for the specific purpose of carbon neutrality are provided.
