Pneumatic Force Research Articles

Formation of Tunable, Emulsion Micro-Droplets Utilizing Flow-Focusing Channels and a Normally-Closed Micro-Valve

A mono-dispersed emulsion is of great significance in many chemical, biomedical and industrial applications. The current study reports a new microfluidic chip capable of forming tunable micro-droplets in liquids for emulsification applications. It can precisely generate size-tunable, uniform droplets using flow-focusing channels and a normally-closed valve, which is opened by a pneumatic suction force. Experimental data showed that micro-droplets with a diameter ranging from several to tens of micrometers could be precisely generated with a high uniformity. The droplet size is experimentally found to be dependent on the velocity of the dispersed-phase liquid, which is controlled by the deflection of the suction membrane. Emulsions with droplet sizes ranging from 5.5 to 55 μm are successfully observed. The variation in droplet sizes is from 3.8% to 2.5%. The micro-droplets have a uniform size and droplets smaller than those reported in previous studies are possible with this approach. This new microfluidic device can be promising for emulsification and other related applications.

Probability of Overturning for Vehicles Moving on a Bridge Deck in a Wind Environment Considering Stochastic Process Characteristics of Excitations

AbstractBased on a wind-vehicle-bridge analysis system and quasi-steady pneumatic force coefficient data obtained from wind tunnel tests, the problem of moving vehicles on a cable-stayed bridge deck overturning in a strong wind environment is studied, with the probability evaluation as the emphasis. It is put forward that the evaluation of a vehicle’s overturning is a probability problem that a stochastic process overpasses a threshold level, and the influence of the statistic process characteristics of excitations on driving safety is profoundly discussed in the paper. The analysis shows that the higher the driving speed, the more obvious the effect of statistic process characteristics tends to be. Moreover, the influence degree of stochastic process characteristics is relevant to the wind velocity range of the dynamic reliability curve and the range of the probability distribution for the mean wind velocity. When the range of the former is broad enough and overlaps with the range of the latter, the infl...

Force and Position Control of the Pneumatic Cylinders through a Microscope with a CCD Camera

In this paper, the pneumatic driven manipulation system is driven by the pneumatic cylinders. The proposed system is built by the designed pneumatic force control system and the microscope, which is integrated with the control interface. Firstly, the characteristics of the pneumatic force control system are measured as the proportional pressure control valve. In accordance with these nonlinear characteristics, a self tuning fuzzy controller with a dead zone compensator is designed to improve precision of the pneumatic force control system. From experimental results, the force error can be controlled within ±1 mN. Next, the real-time image is captured by the microscope with a 1/2 type CCD camera. Through designed image processing, image tracking and image recognition, visual image is used to define the position a probe tip. The distance between the target position and a probe tip can be calculated. Finally, the force control of the pneumatic force control system, calculating the distance between the target position and a probe tip, the control processes are integrated with designed the control interface. Visual C++ code from MFC is used to finish the control interface. From experimental results, the position error can be controlled within ± 1 pixel.

A scalable syringe-actuated microgripper for biological manipulation

Recent developments in the functionality of micro-electromechanical systems (MEMS), particularly for medical and biological applications, have led to an increasing demand for micromanipulation devices. This paper describes the design, fabrication, and testing of a family of pneumatically driven microgrippers which can be scaled to handle millimetre to nanometre compliant and non-compliant objects, with the potential to control gripping forces. In contrast to conventional actuation methods including piezoelectric, magnetic and thermal, pneumatic actuation has the advantages of large power density, the potential for force control, low cost and simplicity. The reported prototypes were fabricated using straightforward processes, in contrast to previously reported pneumatically actuated manipulators. The overall aim of the work is to demonstrate a family of low-cost, polymer based micro grippers that can be actuated manually using pneumatic forces (e.g. via a syringe). A version of the device has been successfully fabricated using laser micromachining and assembled to give an output force of up to 8±0.01mN. The pneumatic actuation was implemented in such as way that it can open the jaws of the micro gripper in a precisely controlled way, demonstrated on a prototype for handling various compliant objects smaller than 200μm in diameter. Finite Element Analysis (FEA) was used to calculate the gripping force, and the results compared with the experimental measurements. The scaling of the demonstrator and its reverse actuation to increase the gripping force are discussed on the basis of the FEA.

Research on Simulation of Electronic-Controlled Pneumatic Regenerative Braking System

In order to improve braking stability and energy recovery ability of electric buses, a new-type electronic-controlled pneumatic regenerative braking system for electric buses was designed. The regenerative braking system controls pneumatic braking force of front and rear wheels by high-speed solenoid valves, which could coordinate mechanical and regenerative braking force effectively. A simulation model of electric bus braking process was established, as well as regenerative braking control strategy. Simulink and AMESim joint simulation analysis of braking process of electric bus was run. The results show that energy recovery of the new-type regenerative braking system is effective and braking control strategy is reasonable.

Development of a Pneumatically-Driven Robotic Forceps with a Flexible Wrist Joint

The present paper describes a pneumatically-driven forceps manipulator for minimally-invasive robot surgery that has a simplified flexible wrist joint for easy fabrication, cost reduction and future miniaturization. The joint structure consists only of a machined spring, and four NiTi super-elastic wires fixed to the joint-end are actuated by pneumatic cylinders in push-pull motions. This mechanism realizes two degrees-of-freedom bending motions of the wrist joint and provides higher manipulation stiffness than other flexible joint mechanisms. Theoretical models of the proposed mechanism are developed; kinematic relation between joint positions and actuator displacements is described as a simple ideal continuum model, and dynamic model of the manipulator is described considering frictional and elastic forces of the joint mechanism. The joint position control system employs a cascade structure: the outer loop of the position control with dynamics compensation and the inner loop of the pneumatic force control. Performances of the joint position control are evaluated through elementary experiments, and effectiveness of the proposed joint mechanism is demonstrated.

Research on Integrated System Control Strategy of Regenerative Braking and Anti-Lock Braking System for Electric Vehicle

Based on ABS System,a regenerative and pneumatic baking system was proposed,which can adjust pneumatic braking force precisely through ABS valve in order to guarantee the distribution of braking force. A control strategy using logic threshold was made,considering ECE regulation,control logic of ABS system,braking torque of motor and charging-discharging characteristic of battery. A co-simulation model was built with the platform of Simulink-AMESim and the simulation was performed under different braking intensity and driving cycles. The results indicate that the vehicle can achieve good braking regeneration effect with ensuring braking stability .Ratio of energy recycling can achieve 16.26% in London bus driving cycles.

Ion transport and focal properties of an ellipsoidal electrode operated at atmospheric pressure

Ion focusing is achieved at atmospheric pressure using an elliptical ion mirror. Working at a fixed distance of several centimeters from the ion source to a mass analyzer entranceaperture, the elliptical electrode increases ion currents reaching in the mass spectrometer by a factor of a hundred. The ion transport efficiency, measured by soft landing of ionized dyes, collecting the resulting dye, and measuring its absorbance, is estimated to be 70% under typical focusing conditions. Simulations of ion motion using SIMION 8.0 reasonably predict the performance of the ion lens in air. Ion current measurements and spatial profiling of the focused beams were facilitated by use of a commercial detector operated in air, in which charge is measured as a function of position, and amplified electronically. This allowed the effects of operating parameters on beam shape and intensity to be measured. The results achieved indicate that analyte ions are directed by pneumatic forces, in the form of charged droplets, and focused electrically. Focusing can be done with good control, both for unsolvated (‘dry’) ions and also for charged microdroplets. The effects of turbulence in the primary ion beam were also characterized.

Using two servovalves to improve pneumatic force control in industrial cylinders

Pneumatic actuation systems present several advantages like low cost, high force/volume ratios, and the absence of significant heat or magnetic field generation. However, its use in complex control tasks is hindered by their highly nonlinear behavior. This drawback is caused not only by the nonlinear behavior of phenomena like friction but also by the large variation of some of the system proprieties with the system state. One of such proprieties is the fluidic stiffness of the actuator, which may suffer significant changes with the piston velocity when the pressure dynamics of both actuator chambers are coupled due to the use of only one servovalve. This dependency can be eliminated if the pressure (or pneumatic force) inside each chamber is independently controlled using two servovalves. In this paper, two pneumatic force allocation strategies are proposed and analyzed. In the first one, the stiffness of the actuator becomes independent of the pneumatic force reference. In the second one, the pneumatic forces are devised to avoid early pressure saturation of the cylinder chambers. Based on an experimental test rig, both strategies are compared against each other and against the use of only one servovalve.

Large-Area Nanotemplate Process and Its Application to Roll Imprint

This study developed a stitching process for unit element nanotemplates based on step and repeat imprinting for use in enlarged soft mold fabrication. This mold was subsequently used for the custom-developed roll-to-plate UV nanoimprint process. The distinctive features of roll UV imprinting include the following: (1) the UV source is embedded within a roll mold made of quartz so that it can illuminate a resist coated on either a transparent or an opaque substrate, (2) the press-contact between the resist and soft mold wrapped around the quartz mold was designed to synchronize the rolling operation with the linear motion of the substrate, which helped minimize the residue thickness, and (3) a compressed pneumatic force was applied along the contact line of the roll imprint, which helped attenuate any possible level mismatch on the stitched mold surface.

Study and Application of a Slide Mode Control on Pneumatic Force Servo System

In this paper, a sliding mode control approach combined with the boundary saturation function approach is put forward and used in a pneumatic force servo system to achieve an exact force control. First, a comparatively accurate model of the system is obtained by using the system identification approach and an analysis is made on the time-varying nature of the model. Then, it is designed by use of the boundary saturation approach, thus overcoming the system instability caused by the non-linearity of the proportional pressure valve and the change of the temperature inside the air cylinder. Finally, the performance of the pneumatic force servo control system is simulated and a comparison is made with the PID control. Results show the feasibility and effectiveness of the approach.

A Scalable Syringe-Actuated Microgripper for Biological Manipulation

Abstract Recent developments in the functionality of micro-electromechanical systems (MEMS), particularly for medical and biological applications, have led to an increasing demand for micromanipulation devices. This paper describes the design, fabrication, and testing of a family of pneumatically driven microgrippers which can be scaled to handle millimetre to nanometre compliant and non-compliant objects, with the potential to control gripping forces. In contrast to conventional actuation methods including piezoelectric, magnetic and thermal, pneumatic actuation has the advantages of large power density, the potential for force control, low cost and simplicity. The reported prototypes were fabricated using straightforward processes, in contrast to previously reported pneumatically actuated manipulators. The overall aim of the work is to demonstrate a family of low-cost, polymer based micro grippers that can be actuated manually using pneumatic forces (e.g. via a syringe). A version of the device has been successfully fabricated using laser micromachining and assembled to give an output force of up to 8 ± 0.01 mN. The pneumatic actuation was implemented in such as way that it can open the jaws of the micro gripper in a precisely controlled way, demonstrated on a prototype for handling various compliant objects smaller than 200 μm in diameter. Finite Element Analysis (FEA) was used to calculate the gripping force, and the results compared with the experimental measurements. The scaling of the demonstrator and its reverse actuation to increase the gripping force are discussed on the basis of the FEA.

望远镜主镜气压力驱动器设计

望远镜主镜气压力驱动器设计

A Neural Network Based Nonlinear Model of a Servopneumatic System

The use of pneumatic devices is widespread among different industrial fields, in tasks like handling or assembly. Pneumatic systems are low-cost, reliable, and compact solutions. However, its use is typically restricted to simple tasks due to the poor performance achieved in applications where accurate motion control is required. One of the key elements required to achieve a good control performance is the model of the servopneumatic system. An accurate model may be of vital importance not only in the simulation steps needed to test the control strategy but also as a part of the controller itself. This work presents a new servopneumatic system model primarily developed for control tasks, namely, to predict pneumatic and friction forces in dynamic tests. The model can also be used in simulation tasks to predict the piston position and velocity. The performance on both applications is validated experimentally.

A Valveless Pneumatic Fluid Transfer Technique Applied To Standard Additions on a Centrifugal Microfluidic Platform

This paper demonstrates a valveless pneumatic fluid transfer technique applicable to centrifugal microfluidic platforms. The technique involves using compressed gas to generate a pneumatic force, which works together with the centrifugal force to control and direct fluid flow. Fluid can be pneumatically transferred from chamber to chamber, greatly decreasing the number of conventional valves required in a multistep process. By varying the rotational frequency of the centrifugal microfluidic platform while pneumatic force is applied, sequential fluid transfer steps can be achieved. The effectiveness of this fluid transfer method is demonstrated by performing a standard additions calibration. This technique is shown to be robust, easy to implement, and greatly reduces the design limitations traditionally associated with centrifugal microfluidic platforms.

A self-contained polymeric cartridge for automated biological sample preparation.

Sample preparation is one of the most crucial processes for nucleic acids based disease diagnosis. Several steps are required for nucleic acids extraction, impurity washes, and DNA/RNA elution. Careful sample preparation is vital to the obtaining of reliable diagnosis, especially with low copies of pathogens and cells. This paper describes a low-cost, disposable lab cartridge for automatic sample preparation, which is capable of handling flexible sample volumes of 10 μl to 1 ml. This plastic cartridge contains all the necessary reagents for pathogen and cell lysis, DNA/RNA extraction, impurity washes, DNA/RNA elution and waste processing in a completely sealed cartridge. The entire sample preparation processes are automatically conducted within the cartridge on a desktop unit using a pneumatic fluid manipulation approach. Reagents transportation is achieved with a combination of push and pull forces (with compressed air and vacuum, respectively), which are connected to the pneumatic inlets at the bottom of the cartridge. These pneumatic forces are regulated by pinch valve manifold and two pneumatic syringe pumps within the desktop unit. The performance of this pneumatic reagent delivery method was examined. We have demonstrated the capability of the on-cartridge RNA extraction and cancer-specific gene amplification from 10 copies of MCF-7 breast cancer cells. The on-cartridge DNA recovery efficiency was 54-63%, which was comparable to or better than the conventional manual approach using silica spin column. The lab cartridge would be suitable for integration with lab-chip real-time polymerase chain reaction devices in providing a portable system for decentralized disease diagnosis.

S121014 腕相撲ロボット製作学習教材の開発([S12101]ヒューマンインターフェース)

In this study, the concept of teaching contents that can be provided by teaching materials for an arm wrestling robot making is proposed. The prototype of robot system called PneumaticRobot by using a pneumatic cylinder, gear, rotary encoder and force sensor is developed. The system for arm wrestling is demonstrated.

Fabrication of a pneumatically driven single-cell trap

This paper describes the creation of a pneumatically driven single-cell trap and its ability to trap a live single cell. The cell-trap device consists of a pneumatic vibrator array and a trap chamber used to trap single cells. The entire structure was manufactured with polydimethylsiloxane (PDMS). External compressed air was used to actuate the pneumatic vibrators. The magnitude and frequency of the pneumatic force were controlled by programmable electromagnetic valves. The live cell in the trap chamber was manipulated using the velocity field of the cell media induced by deformation of the vibrator diaphragm. The cell was successfully trapped in the central equilibrium region of the device, at which point the axial velocity fields generated by the vibrators were minimized. The intracellular calcium response of a single cell induced by mechanical stimuli during cell trapping was measured to verify the effectiveness of the pneumatic cell trap as a stress-free trapping method. The results showed that the internal signaling in the cell was sensitive to the extracellular physical environment. Since the measured intensity of the intracellular calcium of the single cell was very minor, the pneumatic cell trap described in this paper was categorized as a harmless trapping method.

Fabrication of Peristaltic Micropump Driven by a Single-Phase Pneumatic Force

In this paper, we describe a micropump with self-generated peristaltic action, operated by a single-phase pneumatic force for use in a functional microhand. The micropump consists of three actuators and a microfluidic channel. The actuators are connected by a single microchannel for the supply of external compressed air. The self-generated peristaltic motion of the cascaded actuators is created by the pressure loss and the deformation of the actuator diaphragm induced by the applied pressure. Both the fluidic resistance along the microchannel and the fluidic capacitance of the actuator diaphragms result in the sequential deformation of the cascaded actuators, like a triple low-pass filter in an electrical circuit. The micropump was fabricated by soft lithography using only polydimethylsiloxane. The flow rate of the working fluid was observed and measured. The experimental results confirmed that the improved design of the actuators enables a high flow rate of working fluid at a low pressure.

Imaging of Surface Charge and the Mechanism of Desorption Electrospray Ionization Mass Spectrometry

Distributions of charge deposited on surfaces in desorption electrospray ionization mass spectrometry (DESI-MS) were investigated using a static charge measurement apparatus, which gives an output voltage proportional to the local surface charge density. By scanning the probe along the surface and taking measurements at fixed intervals, a contour image of relative charge density reflecting the charge distribution on the surface can be plotted. Through the measured charge distribution and the derived charge density gradient, the motion of charged droplets in the DESI experiment can be inferred. Measurements taken under various DESI operating conditions, including spray pressure, angle, flow rate, and sprayer tip-to-surface distance, show that charge is spread over an area of a few square centimeters under typical conditions; effective desorption occurs from a much smaller area (∼1 mm2) of highest charge density. Higher sheath gas pressures and smaller sprayer tip-to-surface distances lead to concentration of charge distribution into a smaller area, whereas smaller spray angles favor charge distribution over a larger area. The appearance of the highest charge density in front of the DESI sprayer tip and near the MS inlet suggests that charged droplets are moved toward the MS inlet by pneumatic forces and by the vacuum suction, in agreement with results of earlier simulations. The present observations are consistent with previous studies using other techniques and support the accepted droplet splashing DESI mechanism.