The 20th century's robotic systems have been made from stiff materials, and much of the developments have pursued ever more accurate and dynamic robots, which thrive in industrial automation, and ...will probably continue to do so for decades to come. However, the 21st century's robotic legacy may very well become that of soft robots. This emerging domain is characterized by continuous soft structures that simultaneously fulfill the role of robotic link and actuator, where prime focus is on design and fabrication of robotic hardware instead of software control. These robots are anticipated to take a prominent role in delicate tasks where classic robots fail, such as in minimally invasive surgery, active prosthetics, and automation tasks involving delicate irregular objects. Central to the development of these robots is the fabrication of soft actuators. This article reviews a particularly attractive type of soft actuators that are driven by pressurized fluids. These actuators have recently gained traction on the one hand due to the technology push from better simulation tools and new manufacturing technologies, and on the other hand by a market pull from applications. This paper provides an overview of the different advanced soft actuator configurations, their design, fabrication, and applications.
The 21st century's robotic legacy may very well become that of soft robots, which show remarkable features superior to those of conventional robots in tasks requiring delicate manipulation and a high degree of maneuverability. This review discusses a particular type of soft actuators—elastic inflatable actuators—which are driven by pressurized fluids and allow for straightforward integration in soft robotics.
In contrast to microfluidic devices, bulky syringe pumps are widely used to deliver a small amount of solution with high accuracy. Miniaturizing the syringe pump is difficult due to the scale effect ...in the microscale where the friction of the piston–cylinder is dominant and there are few high‐power microactuators. To solve these problems, an on‐chip microsyringe pump without mechanical sliding parts and with high power sources is proposed. The microsyringe pump utilizes the interface between water and oil (electro‐conjugate fluid, ECF) instead of a piston and an electrohydrodynamic (EHD) flow driven by ECF in place of a linear actuator. ECF as a functional fluid has two capabilities: a) making the water–oil interface in microchannels and b) generating an active ECF flow at an applied voltage to withdraw and infuse aqueous solution by the interface. To control the flow direction, ECF‐driven leakless on/off microvalves are also integrated. It is demonstrated that the proposed ECF microsyringe pump synchronized with the ECF on/off microvalves can control the withdrawing and infusing of aqueous solution with high resolution and precision. The experiments prove the feasibility of the microsyringe pump to be embedded as a module for the precise and linear control of flow rates in microfluidic devices.
An on‐chip microsyringe pump integrating the interface between water and oil (electro‐conjugate fluid, ECF) instead of a piston, an electrohydrodynamic (EHD) flow driven by ECF in place of a linear actuator, and ECF‐driven on/off microvalves to control the flow direction is proposed. The proposed pump synchronized with the microvalves that can control the withdrawing and infusing of aqueous solution is demonstrated.
The traditional power sources for generating droplets are bulky devices such as syringe pumps, constant pressure systems and so on, resulting in difficult integration with other microfluidic ...components. To overcome this limitation, we propose and develop a droplet generator with its power sources on a chip (22 × 21 × ~ 1 mm). The compact droplet generator consists of two ECF (electro-conjugate fluid) micropumps, a T-junction channel geometry made of SU-8, a water chamber and three I/O ports. In our methodology, the two ECF micropumps are used to pump the continuous phase fluid (oil) directly and the dispersed phase fluid (water) indirectly on a chip. ECF is a kind of functional and dielectric oil, which can generate a strong and active ECF jet when its corresponding electrodes are applied to high DC voltages. Our ECF micropump is composed of triangular prism and silt electrode pairs (TPSEs) and is able to control flow rates precisely on a chip. In our device, the water in oil droplet is formed by the T-junction geometry. Using MEMS technology, we successfully fabricate the droplet-generator-on-a-chip. Span 80 and dibutyl decanedioate (DBD, Tokyo Chemical Industry Co., Ltd) are used as the surfactant and one type of ECF, respectively. Prior to the characteristic experiments of the T-junction generator, we investigate viscosity, electrical conductivity and relative permittivity of the mixtures of DBD and Span 80 at different concentrations (0 wt%, 1 wt%, 3 wt% and 5 wt%). We also research the impact of the mixtures on the performance of ECF micropumps and the wettability of SU-8 fluidic channels. After that, we confirm the flow pattern diagrams of two-phase fluids, the generated droplet diameter and the droplet production rate for our droplet-generator. Therefore, our droplet generator powered by ECF micropumps can realize the droplet generation on a chip.
Laparoscopic living donor hepatectomy for transplantation has been well established over the past decade. This study aimed to assess its safety and feasibility in pediatric living donor liver ...transplantation (LDLT) by comparing the surgical and long‐term survival outcomes on both the donor and recipient sides between open and laparoscopic groups. The medical records of 100 patients (≤17 years old) who underwent ABO‐compatible LDLT using a left lateral liver graft between May 2008 and June 2016 were analyzed. A total of 31 donors who underwent pure laparoscopic hepatectomy and their corresponding recipients were included in the study; 69 patients who underwent open living donor hepatectomy during the same period were included as a comparison group. To overcome bias from the different distributions of covariables among the patients in the 2 study groups, a 1:1 propensity score matching analysis was performed. The mean follow‐up periods were 92.9 and 92.7 months in the open and laparoscopic groups, respectively. The mean postoperative hospital stay of the donors was significantly shorter in the laparoscopic group (8.1 days) than in the open group (10.6 days; P < 0.001). Overall, the surgical complications in the donors and overall survival rate of recipients did not differ between the groups. Our data suggest that the laparoscopic environment was not associated with long‐term graft survival during pediatric LDLT. In addition, the laparoscopic approach for the donors did not adversely affect the corresponding recipient's outcome. Laparoscopic left lateral sectionectomy for living donors is a safe, feasible, and reproducible procedure for pediatric liver transplantation.
In this study, nanopatterned Nafion microelectrode arrays for in vitro cardiac electrophysiology are reported. With the aim of defining sophisticated Nafion nanostructures with highly ionic ...conductivity, fabrication parameters such as Nafion concentration and curing temperature are optimized. By increasing curing temperature and Nafion concentration, the replication fidelity of Nafion nanopatterns when copied from a polydimethylsiloxane master mold are controlled. It is also found that cross‐sectional morphology and ion current density of nanopatterned Nafion strongly depends on the fabrication parameters. To investigate this dependency, current‐voltage analysis is conducted using organic electrochemical transistors overlaid with patterned Nafion substrates. Nanopatterned Nafion is found to allow higher ion current densities than unpatterned surfaces. Furthermore, higher curing temperatures are found to render Nafion layers with higher ion/electrical transfer properties. To optimize nanopattern dimensions, electrical current flows, and film uniformity, a final configuration consisting of 5% nanopatterned Nafion cured at 65 °C is chosen. Microelectrode arrays (MEAs) are then covered with optimized Nafion nanopatterns and used for electrophysiological analysis of two types of induced pluripotent stem cell‐derived cardiomyocytes (iPSCs‐CMs). These data highlight the suitability of nanopatterned Nafion, combined with MEAs, for enhancing the cellular environment of iPSC‐CMs for use in electrophysiological analysis in vitro.
Organic electrochemical transistors with Nafion nanointerfaces are presented not only to give in vivo‐like fibrous cellular environments, but also integrate with microelectrode arrays to understand the mechanism of recording electrophysiology through ion permeable layers. Optimization of nanostructure fidelity and ion permeability under different fabrication parameters are conducted. Moreover, nanopatterned Nafion‐coated electrode arrays are used to evaluate electrophysiological recordings of cardiomyocytes.
Figure: Schematics of the fabrication process of the SU-8 adhesive tape by using a dose-controlled UV exposure method.
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•A partially-crosslinked SU-8 adhesive tape was proposed by ...using the dose-controlled UV exposure, for the fast packaging of fluidic devices.•The proposed SU-8 adhesive tape consists of an adhesive layer (uncrosslinked) onto the backing material (crosslinked) with fluid connections.•The applications to a T-junction droplet generator and a shallow channel demonstrate the feasibility of our proposed method.
This paper proposes a novel SU-8 adhesive tape by using the dose-controlled UV exposure method, which enables the fast packaging with fluidic interconnections for microfluidic sensors and actuators. The conventional packaging for microfluidic devices demands two complicated steps: (1) to drill the fluidic connections on the glass cover in the first process, which may make the glass cover broken due to poor machinability of glass; and then (2) to spread a thin adhesive on the cover in the second process, which may induce the clogging of the fluidic connections. To realize a fast and simple packaging for microfluidic devices, we propose a versatile method that employs a partially-crosslinked SU-8 adhesive tape composed of an adhesive layer (uncrosslinked SU-8) onto the backing material (crosslinked SU-8) with fluid connections, which can be fabricated in one simple step. We choose a suitable substrate from which we can release the SU-8 adhesive tape and build the mathematic model of the dose-controlled UV exposure method which can estimate the thickness of the crosslinked SU-8. Then, we investigate the influence of developing time on the formation of the SU-8 adhesive tape. We also examine the bonding quality by using the visual inspection method and measuring the bonding strength based on the pull-test experiments. Moreover, its applications to a T-junction droplet generator and a shallow channelprove the feasibility to be widely applied to microfluidic sensors and actuators.
Previously, we have developed ECF micropumps with triangular prism and slit electrode pairs (TPSEs) fabricated by the UV-LIGA. However, the previous KMPR molds have a limit to attain ...higher-aspect-ratio TPSEs. As a promising substitute, the ultrathick SU-8 molds are preferable for the TPSEs due to higher-aspect-ratio ability, but their difficult removal remains an annoying problem. To solve this problem, we first propose a novel hybrid removal method combining <inline-formula> <tex-math notation="LaTeX">\text{C}O_{2} </tex-math></inline-formula> laser engraving with <inline-formula> <tex-math notation="LaTeX">O_{2} </tex-math></inline-formula>/CF 4 plasma to achieve the fast, non-swelling, and complete removal of ultrathick SU-8 micromolds for higher-aspect-ratio TPSEs. The <inline-formula> <tex-math notation="LaTeX">\text{C}O_{2} </tex-math></inline-formula> laser engraving is utilized as the main process to remove most SU-8, while the <inline-formula> <tex-math notation="LaTeX">O_{2} </tex-math></inline-formula>/CF 4 plasma is adopted as the post-treatment to remove the remaining SU-8. To gather the proper fabrication conditions, we quantitatively analyze the effects of laser power, laser scan speed, and laser-pass numbers on the SU-8 ablation thickness. We successfully fabricated TPSEs of <inline-formula> <tex-math notation="LaTeX">590~\mu \text{m} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">970~\mu \text{m} </tex-math></inline-formula> in height by selectively removing SU-8 micromolds of 620 and <inline-formula> <tex-math notation="LaTeX">1100~\mu \text{m} </tex-math></inline-formula> in thickness. This achievement confirmed that our hybrid removal technology could remove the crosslinked SU-8 effectively and efficiently. We further experimentally proved the fascinating potential of our hybrid removal in improving the output performance of ECF micropumps. This promising hybrid removal opens the door to the easier fabrication of ultrathick metallic microstructures by UV-LIGA. 2017-0320
Background
The aim of this study was to validate the safety and feasibility of pure laparoscopic extended cholecystectomy (LEC) by comparing the outcome with that of open extended cholecystectomy ...(OEC). Moreover, on the basis of our experience, we also aimed to investigate the learning curve of pure LEC.
Methods
This single-center study enrolled patients who were diagnosed primary gallbladder cancer with pathologically confirmed and underwent R0 resection with curative intent between January 2016 and December 2019. A total of 31 patients who underwent OEC and 17 patients who underwent LEC were selected. Propensity score matching analysis was performed in a 1:1 ratio using the nearest-neighbor matching method, and clinical information was retrospectively collected from medical records and analyzed.
Results
The postoperative hospital stay was statistically shorter in the LEC group (7 days) than in the OEC group (12 days). The overall surgical complication rate did not differ between the two groups. The 1- and 3-year disease-free survival rates were 82.4% and 82.4% in the OEC group and 94.2% and 71.5% in the LEC group, respectively (
P
= 0.94). Considering the correlation between the number of cumulative cases and the operation time and between the number of cumulative cases and the number of retrieved lymph nodes in the LEC group, as the cases were accumulated, both the operation time and the number of retrieved lymph nodes had a statistically significant correlation with the number of cases.
Conclusions
LEC showed a significant advantage in terms of achieving shorter postoperative hospital stay and similar results to OEC with respect to overall complications and pathological outcomes. The present results confirm that laparoscopy can be considered a safe treatment for primary gallbladder cancer in selected patients.
UV-LIGA process has manifested its potential in the fabrication of high-aspect-ratio metallic microstructures. However, how to attain the complete, fast, and non-swelling removability of the ...crosslinked SU-8 micromolds remains a grand challenge. To address this challenge, we propose an effective and efficient removing method utilizing CO
2
laser ablation followed by O
2
/CF
4
plasma finishing for the fabrication of metallic microstructures in UV-LIGA. As the focused CO
2
laser beam with a specific wavelength ablates the non-metal polymers but does not react with the electroformed nickel, it is used as the primary step to remove most of crosslinked SU-8 without swelling in a very short time. As the finishing step, the O
2
/CF
4
plasma is then implemented to remove the residues and keep the metallic structures clean. We quantitatively investigate the effects of laser power, laser scanning speed, and laser pass numbers on the SU-8 ablation thickness to obtain the proper removal conditions. Utilizing the UV-LIGA fabricated micromolds and the proposed removal method, we successfully fabricate the metallic microstructures with aspect ratio up to five. Also, we evaluate the performance of the proposed method by changing various shapes, grating widths, and space intervals for the grating structure. These results prove that our method is effective and efficient in removing the SU-8 micromolds in UV-LIGA for the fabrication of metallic microstructures.
Schematic of the proposed bidirectional ECF micropump.
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•We propose a new type of the ECF micropump which can generate the ECF jet in both directions by switching the DC voltage.•One ...ECF jet generator consists of a pair of triangular prism electrodes, facing each other across the slit electrode.•The designed bidirectional ECF micropump is fabricated by MEMS process.•The bidirectional ECF micropump shows the same static characteristic in both directions.•The step response and frequency response of the bidirectional ECF micropump are clarified.
The previously reported unidirectional ECF micropumps are not applicable to some soft actuators, which need inflating and deflating processes. To overcome this limitation, we propose, design, fabricate and characterize an ECF (Electro-Conjugate Fluid) bidirectional micropump. The simply designed bidirectional ECF micropump has five sets of electrodes. One set of electrodes are composed of two triangular electrodes with a face-to-face distribution and a shared and separated slit electrode. By applying DC voltage to one of the triangular electrodes and grounding the slit electrode, the device can generate an ECF jet along the triangular direction in the microchannel. Therefore, an ECF jet can be achieved in each direction by simply switching the applied DC voltage to one of the two triangular electrodes. This bidirectional ECF micropump without any mechanical moving parts is successfully fabricated by a MEMS-based process. We demonstrate the static and dynamic performance of our bidirectional ECF micropump. In the static evaluation, we primarily focus on the maximum pressure and flow rate generated by the bidirectional ECF micropump. In the dynamic evaluation, we test the responsiveness, model the relationship between switching frequency and output pressure, and compare the theoretical values with the experimental results. Therefore, this study indicates that bidirectional ECF micropumps can be a good candidate for a driving source to realize reciprocating motions.
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