Non-liquid Environments Research Articles

Magnetic Levitation Actuation and Motion Control System with Active Levitation Mode Based on Force Imbalance

Accurate large-displacement magnetic levitation actuation and its stability remain difficult in non-liquid environments. A magnetic levitation actuation and motion control system with active levitation mode is proposed in this paper. The actuating force of the system is generated by the external magnetic field. A neural network proportion-integration-differentiation (PID) controller is designed for active actuation, and a force imbalance principle is built for the step motion mode. Dual electromagnetic actuators are configured to generate a superimposed magnetic field, ensuring that the electromagnetic force on the ball is more uniform and stable than single actuators. Dual-hall-structure sensors are used to measure displacement, thereby reducing overshoot and ensuring stability whilst motivating the ball. Due to the high adaptability of the neural network to complex systems with nonlinear and ambiguous models, the PID controller composed of neurons has stronger adaptability through tuning the PID controller parameters automatically. Furthermore, the proposed controller can solve the shortcoming that the deviation between the controlled object and the steady-state operating point increases and the tracking performance deteriorates rapidly. The strong robustness and stability in active levitation and motion control is achieved during both ascending and descending processes.

Light‐Induced In‐Plane Rotation of Microobjects on Microfibers (Laser Photonics Rev. 16(5)/2022)

Optical Manipulation of Microobjects In article number 2100561, Wei Lyu, Weiwei Tang, Wei Yan, and Min Qiu realize in-plane rotation of a gold microplate on a microfiber by pulsed light. The motion is attributed to light-induced elastic waves other than ‘conventional’ optical force that is too tiny to tame friction between two solid interfaces. The underlying mechanisms highlight the joint role of spatial gradient of optical absorption and asymmetry in two wings of the plate, which lead to unbalanced, nonuniform elastic waves. The results offer new insights into the study of the light-induced actuation of microobjects in nonliquid environments.

Light‐Induced In‐Plane Rotation of Microobjects on Microfibers

AbstractThe transfer of momentum carried by photons into a microobject has been widely used to actuate the microobject. However, this scheme is defective in nonliquid environments due to the scale gap between friction force (N) and optical force (pN). To overcome this problem, the researchers have recently proposed to take advantage of elastic waves induced by optical absorption. Grounded on this insight, here, the in‐plane rotation of a gold microplate in its surface contacting with a microfiber is demonstrated and characterized. The in‐plane rotation is actuated by laser pulses guided into the microfiber, and its speed increases with laser power. Furthermore, the underlying physical mechanisms supported with numerical simulations are examined, highlighting the joint role of the spatial gradient of optical absorption and the asymmetry in two wings of the plate. The combined experimental and theoretical results offer new insights into the study of the light‐induced actuation of the microobjects in nonliquid environments, an emerging field far from being mature in both comprehensive understanding and practical applications.

Micro-scale opto-thermo-mechanical actuation in the dry adhesive regime

Realizing optical manipulation of microscopic objects is crucial in the research fields of life science, condensed matter physics, and physical chemistry. In non-liquid environments, this task is commonly regarded as difficult due to strong adhesive surface force (~µN) attached to solid interfaces that makes tiny optical driven force (~pN) insignificant. Here, by recognizing the microscopic interaction mechanism between friction force—the parallel component of surface force on a contact surface—and thermoelastic waves induced by pulsed optical absorption, we establish a general principle enabling the actuation of micro-objects on dry frictional surfaces based on the opto-thermo-mechanical effects. Theoretically, we predict that nanosecond pulsed optical absorption with mW-scale peak power is sufficient to tame µN-scale friction force. Experimentally, we demonstrate the two-dimensional spiral motion of gold plates on micro-fibers driven by nanosecond laser pulses, and reveal the rules of motion control. Our results pave the way for the future development of micro-scale actuators in non-liquid environments.

Electric-field-guided 3D manipulation of liquid metal microfleas

ABSTRACT Liquid metal micromotors have attracted mounting interest over the past decade, but their property of sticking to many surfaces has limited their controllable manipulation in three dimensions (3-D). In this work, we demonstrate a versatile and generic approach in manipulating Gallium-based liquid metal microfleas (LMMFs) on solid surfaces by strategically applied electric (E-) fields, in which the adhesion of LMMFs to solid surfaces is greatly reduced by tailoring the thickness of the oxide skins of the liquid metal. Numerical simulations and experimental demonstrations illustrate that the LMMFs can be readily driven to jump along prescribed trajectories with high localization accuracy (the order of ~10 microns). The prowess of the precision manipulation of LMMFs is further demonstrated in several practical applications, including the walking of LMMFs on the stairs, the micro-welding for cracked conducting wire, as well as the on-demand jumping of LMMFs on a “mini-piano.” Such a proposed approach provides a convenient, rather generic, E-field-based strategy for manipulation of LMMFs in non-liquid environments with a configurable, switchable, and programmable fashion, offering considerable potential for diverse practical applications in the near future.

Plasmon-driven nanowire actuators for on-chip manipulation

Chemically synthesized metal nanowires are promising building blocks for next-generation photonic integrated circuits, but technological implementation in monolithic integration will be severely hampered by the lack of controllable and precise manipulation approaches, due to the strong adhesion of nanowires to substrates in non-liquid environments. Here, we demonstrate this obstacle can be removed by our proposed earthworm-like peristaltic crawling motion mechanism, based on the synergistic expansion, friction, and contraction in plasmon-driven metal nanowires in non-liquid environments. The evanescently excited surface plasmon greatly enhances the heating effect in metal nanowires, thereby generating surface acoustic waves to drive the nanowires crawling along silica microfibres. Advantages include sub-nanometer positioning accuracy, low actuation power, and self-parallel parking. We further demonstrate on-chip manipulations including transporting, positioning, orientation, and sorting, with on-situ operation, high selectivity, and great versatility. Our work paves the way to realize full co-integration of various functionalized photonic components on single chips.

Research on two-dimensional external magnetic drive method of maglev ball based on force imbalance.

In this paper, an external magnetic driving method of a maglev ball based on force imbalance is first proposed to meet the requirement that the maglev ball is moved linearly in the axis direction of the electromagnetic actuator in the non-liquid environment. This method is expected to be better applied in the fields of industrial and medical miniature curved tube. The maglev ball is a magnetic levitated object. Based on the interpolation algorithm, the two-dimensional stepwise levitation motion trajectory of the maglev ball is designed as the target curve of the motion. The maglev ball can be driven with a large range along a specified motion path. Compared with the 1.0 mm step input, the overshoot of a 0.2 mm step input is decreased by 73.7% and 73.6% in the descending phase and the ascending phase, respectively. Therefore, fluctuation of the step response of the maglev ball is improved by smaller step control. However, the larger the step input, the faster the speed and the larger the levitation gap. Under the condition of a 1.0 mm step input, the maximum levitation gap can be up to 20.487 mm, and the speed of the maglev ball can reach 3.086 mm/s. Compared with static levitation control, the position of the maglev ball is fluctuated severely due to radial runout under motion control conditions, and the position accuracy can reach ±0.03 mm.

High-precision resin layer polishing of carbon fiber mirror based on optimized ion beam figuring process

Based on the advantages of stress-free and non-liquid environment, ion beam polishing is the ideal processing technology for the Resin modified layer polishing of the carbon fiber mirror. Since the glass transition temperature of the resin is low, the energy absorbed by the surface of the mirror during ion beam processing can cause localized high temperatures, which can lead to the risk of resin softening. The finite element analysis software was used to simulate the heat transfer process of Ion beam acting on the resin modified layer. The optimum process parameters of the ion beam polishing were determined. At the same time, the resin layer surface polishing test was completed. The experimental results show that the surface polishing of the resin modified layer can be achieved by ion beam processing, and it has the convergence property and the correctness of the theoretical model is Verified.In addition, according to the process instability phenomenon in the ion beam figuring of carbon fiber-based resin modified layer, analytical research on factors affecting the accuracy of ion beam processing were carried out. The effects of various factors on the processing precision of carbon fiber resin layer were analyzed by combing and theoretical analysis,combined with experimental research to determine the amount of influence, and finally put forward corresponding solutions.

Montmorillonite immobilized Fe/Ni bimetallic prepared by dry in-situ hydrogen reduction for the degradation of 4-Chlorophenlo

This study puts forward a new way to produce montmorillonite immobilized bimetallic nickel-iron nanoparticles by dry in-situ hydrogen reduction method in the non-liquid environment, which effectively inhibits the oxidation of iron and nickel during the synthesis process and improves the reactivity of the material. The degradation of 4-Chlorophenol (4-CP) was investigated to examine the catalytic activity of the material. The morphology and crystal properties of the montmorillonite-templated Fe/Ni bimetallic particles were explored by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction studies, and energy dispersive X-ray spectroscopy analysis. Results suggest that Fe and Ni particles were homogeneously dispersed on the montmorillonite. The optimization of Ni content and reduction temperature over the degradation of 4-CP was also studied. The introduction of Ni intensely improved the degradation of 4-CP and reached over 90% when Ni content was 28.5%. The degradation rate increased significantly with the increase of reduction temperature and showed maximum activity at the reduction tempreature of 800 °C. This study offers a new method to fabricate montmorillonite immobilized Fe/Ni bimetallic nanoparticles in the non-liquid environment and the composites exhibited high degradation activity to chlorinated organic compounds.

Nanoscale Lamb wave-driven motors in nonliquid environments.

Achieving light-driven motions in nonliquid environments presents formidable challenges, because microsized objects experience strong dry adhesion and intend to be stuck to contact surfaces with great tenacity. Here, in air and vacuum, we show rotary locomotion of a micrometer-sized metal plate with ~30 nm thickness, revolving around a microfiber. This motor is powered by pulsed light guided into the fiber as a coordinated consequence of an optically excited Lamb wave on the plate and favorable configuration of plate-fiber geometry. The motor, actuated by designed light pulses, crawls stepwise with subnanometer locomotion resolution. Furthermore, we can control the rotation velocity and step resolution by varying the repetition rate and pulse power, respectively. A light-actuated micromirror scanning with 0.001° resolution is then demonstrated on the basis of this motor. It offers unprecedented application potential for integrated micro-opto-electromechanical systems, outer-space all-optical precision mechanics and controls, and laser scanning for miniature lidar systems.

Influence of electrical double-layer dispersion forces and size dependency on pull-in instability of clamped microplate immersed in ionic liquid electrolytes

Plate-type clamped microplate is of the most common constructive elements for developing in-liquid-operating devices. While the electromechanical behavior of clamped microplate in non-liquid environments has exclusively been addressed in the literature, no theoretical studies have yet been conducted on precise modeling of the clamped microplate in electrolyte liquid. Herein, the electromechanical response and instability of the clamped microplate immersed in ionic electrolyte media are investigated. The electrochemical force field is determined using double layer theory and linearized Poisson–Boltzmann equation. The presence of dispersion forces, i.e., Casimir and van der Waals attractions, are included in the theoretical model considering the correction due to the presence of liquid media between the interacting surfaces (three-layer model). To this end, a kind of microplate has been designed, i.e., a square microplate with all edges clamped supported. The strain gradient elasticity is employed to model the size-dependent structural behavior of the clamped microplate. To solve the nonlinear constitutive equation of the system, Extended Kantorovich Method, is employed and the pull-in parameter of the microplate are extracted. Impacts of the dispersion forces and size effect on the instability characteristics are discussed as well as the effect of ion concentration and potential ratio. It is found that the significant difference between the pull-in instability parameters in the modified strain gradient theory and the classical theory for thin microplates is merely due to the consideration of size effect parameter in the modified strain gradient theory. To confirm the validity of formulations, the numerical values of the results are compared. The results predicted via the aforementioned approach are in excellent agreement with those in the literature. Some new examples are solved to demonstrate the applicability of the procedure.

Cancer biomarker sensing using packaged plasmonic optical fiber gratings: Towards in vivo diagnosis

This work presents the development of an innovative plasmonic optical fiber (OF) immunosensor for the detection of cytokeratin 17 (CK17), a biomarker of interest for lung cancer diagnosis. The development of this sensing platform is such that it can be assessed in non-liquid environments, demonstrating that a surface plasmon resonance (SPR) can be excited in this case. For this purpose, detections have been first carried out on CK17 encapsulated in gel matrix in the aim of mimicking tissue samples. Gold-coated OF immunosensors were embedded in a specifically designed packaging providing enough stiffness to penetrate into soft matters. Resulting reflected spectra have revealed, for the first time, the presence of a stable SPR signal recorded in soft matters. Experiments conducted to detect CK17 trapped in a porous polyacrylamide gel matrix have highlighted the specific and selective biosensor response towards the target protein. Finally, the packaged OF immunosensor has been validated by a preliminary test on human lung biopsy, which has confirmed the ex-vivo CK17 detection. Consequently, this work represents an important milestone towards the detection of biomarkers in tissues, which is still a clinical challenge for minimally-invasive in vivo medical diagnosis.

Environmental Factors on Aging of Nitrile Butadiene Rubber (NBR) - A Review

Nitrile butadiene rubber (NBR) comes into widespread applications due to the excellent performances, but it is susceptible to aging during its storage and usage periods. This paper surveys the external factors that act on the aging process of NBR. The aging of NBR in liquid environment, and non-liquid environment such as thermo-oxidative aging, ozone aging, stress aging and radiation aging, are considered. The emphasis of present works is test of physical and mechanical properties of NBR, and the micro analysis should gain special attention. One direction of future research on NBR aging is the coupling effects of various factors included in this paper.

Nasopharyngeal Acid Reflux and Eustachian Tube Dysfunction in Adults

This study aimed to evaluate the relationship between nasopharyngeal pH and Eustachian tube dysfunction (ETD) in adults. Unmatched case-control study. Forty-one subjects, 20 adults with a diagnosis of ETD and 21 healthy adults as controls, were enrolled from an outpatient clinic. All subjects had a Dx-pH probe placed near the torus tubarius in the posterior nasopharynx for 24 hours. The pH values were recorded every 0.5 second. Decreases in pH were considered as reflux events if the pH dropped below 5.5. The average nasopharyngeal pH value was 6.90 (range, 5.33-7.73) in the subjects with ETD and 7.07 (range, 5.99-7.94) in the controls. The difference between the 2 groups was not statistically significant (P = .30). The ETD group, on average, had a higher number of nasopharyngeal reflux events (2.3 +/- 1.6 vs 0.8 +/- 1.2, respectively; P = .002) and higher reflux finding score (3.6 +/- 2.7 vs 0.4 +/- 1.4, respectively; P < .00 I) than the control group. By using a novel pH probe that allows detection of acidity in a nonliquid environment, a comparison of nasopharyngeal pH between control patients and those with ETD was performed. Eustachian tube dysfunction was more likely to be associated with a higher number of nasopharyngeal reflux events and higher reflux finding score. Nasopharyngeal reflux may have a role in the pathogenesis of ETD.

Detecting Nasopharyngeal Reflux: A Novel pH Probe Technique

We sought to ascertain the normal pH values in the aerosolized environment of the nasopharynx in healthy subjects and utilize a novel pH probe that allows measuring acidity in a nonliquid environment. Between November 2009 and February 2011, healthy volunteers without a history of reflux or eustachian tube dysfunction were enrolled in the prospective study. A total of 20 subjects had a Dx-pH Measurement System Probe (Respiratory Technology Corp) placed near the torus tubarius. The pH probe records the pH throughout the 24-hour study. A pH below 5.5 while the subject was upright or below 5.0 while the subject was supine was used as a criterion to determine a reflux event. Recording was stopped during meals. For normal individuals with no history of reflux or eustachian tube dysfunction, the pH values obtained from the nasopharynx ranged from 6.10 to 7.92. The average pH was 7.03 (SD, 0.67). Eight subjects (40%) had at least 1 reflux event during the 24-hour pH study. By utilizing a novel self-condensing pH probe, we were able to perform a 24-hour pH study in the nasopharynx of 20 healthy individuals. In our study, the average pH for individuals without symptomatic reflux or eustachian tube dysfunction was 7.03. Interestingly, 8 control subjects had at least 1 episode of pH below 5.5 while awake or below 5.0 while asleep, which was considered to be a reflux event in our study.

Detecting Reflux in Adults with Eustachian Tube Dysfunction

Objective: 1) Ascertain whether adult patients with Eustachian tube dysfunction (ETD) have a higher incidence of reflux into the nasopharynx compared with controls. 2) Utilize recent advances in pH probe technology to detect acidity at the Eustachian tube orifice for direct comparison. Method: A prospective study was performed on 38 adult patients in an outpatient setting between November 2009 and February 2011. Seventeen patients with Eustachian tube dysfunction and 21 control subjects had a Dx-pH probe (Restech, San Diego, California 2006) placed near the torus tubarius in the posterior nasopharynx for 24 hours. Results: The average pH value obtained from the nasopharynx of adults with no history of ETD was 7.03 (range, 6.10-7.92; SD, 0.69). In comparison, the average pH for patients with ETD was 6.90 (range, 5.33-8.06; SD, 0.77). This P value for this difference was .48. The average number of reflux events for subjects was 0.55 events over a 24-hour period for controls and 2.1 for patients with ETD. Decreases in pH were considered reflux events if the pH dropped below 5.5 while in the upright position or below 5.0 in the supine position. Conclusion: By utilizing a novel pH probe that allows detection of acidity in a non-liquid environment, a comparison of nasopharyngeal pH between control patients and those with ETD was performed. A trend toward higher numbers of reflux events was found in patients with ETD when compared to control subjects.

Resonant Electron Tunneling Through Azurin in Air and Liquid by Scanning Tunneling Microscopy

Electron transfer through the redox metalloprotein azurin immobilized on Au (111) by its disulphide bridge is studied by scanning tunneling microscopy (STM) in buffer solution and (for the first time) in air. STM analysis gives evidences of a stable and robust binding of the molecules in both cases. Bright spots, associated with azurin molecules, are clearly visible in STM images. The image contrast of adsorbed azurin is highly affected by the bias potential with proteins visible only for some well-defined voltage values. This experimental demonstration of the possibility to induce tunneling through azurin in air could disclose very interesting perspectives for the development of protein-based hybrid nanodevices operating in nonliquid environments.

Structural stability study of protein monolayers in air.

The assessment of the folding and of the structural stability of a protein in air, upon immobilization in the solid state, represents a critical point from both a fundamental point of view and for the development of solid state nanobioelectronics. The recent demonstrations by Rinaldi et al. [R. Rinaldi et al., Adv. Mater. 14, 1453 (2002); Appl. Phys. Lett. 82, 472 (2003); Ann. (N.Y.) Acad. Sci. 1006, 187 (2003)] of protein-based solid state devices and transistors working in air have raised an intriguing question about the behavior of a biomolecule under nonphysiological conditions. The operation principle of the realized devices is based on the physiological electron transfer function of the metalloprotein azurin. This means that azurin should retain its shape and functionality also in the solid state when utilized in air and at room temperature. In this Brief Report, we prove this claim by analyzing the conformational state of the azurin monolayers developed for such devices by means of intrinsic fluorescence spectroscopy. We show that the immobilization of azurins in the solid state under nonliquid conditions, by means of a specific chemisorption process, does not necessarily lead to protein denaturation. This result is of great importance because it opens up interesting perspectives for the development of solid state hybrid nanodevices for electronic applications requiring nonliquid environments.