Vacuum Source Research Articles

Controlling Biomedical Devices Using Pneumatic Logic.

Many biomedical devices are powered and controlled by electrical components. These electronics add to the cost of a device (possibly making the device too expensive for use in resource-limited or point-of-care settings) and can also render the device unsuitable for use in some environments (for example, high-humidity areas such as incubators where condensation could cause electrical short circuits, ovens where electronic components may overheat, or explosive or flammable environments where electric sparks could cause serious accidents). In this work, we show that pneumatic logic can be used to power and control biomedical devices without the need for electricity or electric components. Originally developed for controlling microfluidic "lab-on-a-chip" devices, these circuits use microfluidic valves like transistors in air-powered logic "circuits." We show that a modification to the basic valve design-adding additional air channels in parallel through the valve-creates a "high-flow" valve that is suitable for controlling a broad range of bioinstruments, not just microfluidics. As a proof-of-concept, we developed a high-flow pneumatic oscillator that uses five high-flow Boolean NOT gates arranged in a loop. Powered by a single constant vacuum source, the oscillator provides five out-of-phase pneumatic outputs that switch between vacuum and atmospheric pressure every 1.3s. Additionally, a user can adjust the frequency of the oscillator by squeezing a bellows attached to one of the pneumatic outputs. We then used the pneumatic oscillator to power a low-cost 3D-printed laboratory rocker/shaker commonly used to keep blood products, cell cultures, and other heterogeneous samples in suspension. Our air-powered rocker costs around $12 USD to build and performs as well as conventional electronic rockers that cost $1000 USD or more. This is the first of many biomedical devices that can be made cheaper and safer using pneumatic logic.

The Study Design of a Double-Action Plate Vacuum Pump

Rotary plate vacuum pumps have become widely used as a source of vacuum for milking systems. The main features of a plate vacuum pump include design simplicity, high efficiency, low cost and adaptability to climatic conditions. A plate vacuum pump requires the improvement of specific performance indicators. This refers to the indicator of specific productivity and specific energy intensity. It is possible to improve the vacuum pump by optimizing the design parameters and technological models of operation. The known studies allow the establishment of rational geometric parameters, the number of plates, the ratio of the main dimensions and eccentricity. However, the problem of reducing the degree of uneven air pumping from the vacuum system needs a scientific solution. The use of a vacuum cylinder in a vacuum line of an increased diameter partially solves the problem of vacuum pressure fluctuations. But such a decision requires additional material costs. In addition, the power of a vacuum pump increases to compensate for the pressure losses. In this study, the authors proposed the design of a double-action plate vacuum pump. It was proven that the simultaneous operation of combined rotors with plates shifted by 45° decreased the degree of air pumping by 7.8%. The research results indicated that the productivity of the developed vacuum pump increased by 13.6%. The drive power increased by 12%, and the specific energy intensity was 20% lower than that of vacuum pumps with similar geometric parameters. The relationship between rational kinematic and design parameters of a double-action vacuum pump was established.

Ambient ionisation mass spectrometry for drug and toxin analysis: A review of the recent literature.

Ambient ionisation mass spectrometry (AIMS) is a form of mass spectrometry whereby analyte ionisation occurs outside of a vacuum source under ambient conditions. This enables the direct analysis of samples in their native state, with little or no sample preparation and without chromatographic separation. The removal of these steps facilitates a much faster analytical process, enabling the direct analysis of samples within minutes if not seconds. Consequently, AIMS has gained rapid popularity across a diverse range of applications, in particular the analysis of drugs and toxins. Numerous fields rely upon mass spectrometry for the detection and identification of drugs, including clinical diagnostics, forensic chemistry, and food safety. However, all of these fields are hindered by the time-consuming and laboratory-confined nature of traditional techniques. As such, the potential for AIMS to resolve these challenges has resulted in a growing interest in ambient ionisation for drug and toxin analysis. Since the early 2000s, forensic science, diagnostic testing, anti-doping, pharmaceuticals, environmental analysis and food safety have all seen a marked increase in AIMS applications, foreshadowing a new future for drug testing. In this review, some of the most promising AIMS techniques for drug analysis will be discussed, alongside different applications of AIMS published over a 5-year period, to provide a summary of the recent research activity for ambient ionisation for drug and toxin analysis.

Probing vacuum field fluctuations and source radiation separately in space and time

Probing vacuum field fluctuations and source radiation separately in space and time

Negative pressure wound therapy in the treatment of purulent wounds of the maxillofacial superficial cellular spaces

Relevance. The choice of the method for purulent wound management (open or closed) is a relevant problem in surgery. The way of drainage is the fundamental factor of the effect on the wound. The open-drainage systems are most frequent in maxillofacial surgery, and the drain is passive, combined with various drug administration. It has significant drawbacks: the short action of the injected substances, painful dressing changes, long wound healing time, etc. The instillation drainage therapy is not widely available and is used only in clinics with appropriate equipment. Active draining (negative pressure suction drainage system) allows closed wound management. Though, it is still rarely used in maxillofacial surgery.Purpose. The study aimed to increase the effectiveness of the treatment of maxillofacial purulent wounds formed after the incision of odontogenic soft tissue purulent inflammatory processes using negative pressure wound therapy.Material and methods. The study was a comparative analysis of clinical and laboratory indicators of 303 patients with purulent wounds formed after incision of superficial cellular spaces’ abscesses and phlegmons. The patients formed two groups: the main group had negative pressure wound therapy (NPWT), and the comparison group had wound treatment with the traditional open method. NPWT methodology included the tubular drain placement into the purulent cavity formed after the incision and administration of a surgical film on the wound. The distal tube end was attached to a vacuum source that simultaneously was a canister for exudate collection and analysis. We followed up on clinical manifestations and endointoxication indicators and studied the wound content toxicity and the dynamics of the respiratory enzyme succinate dehydrogenase activity.Results. The negative pressure system appears to allow fast and atraumatic wound management, reducing the inflammatory stage of the wound healing process, promoting quick normalization of endointoxication parameters, which improves the patient’s general condition (fast resolution of the clinical signs), and the effect of vacuum-assisted closure allows avoiding secondary wound closure.Conclusion. Low-dose negative pressure provides the wound healing process with specific characteristics. Continuous exudate aspiration promotes rapid elimination of bacteria and detoxification of the wound and surrounding tissues, normalization of endointoxication parameters, provides anti-oedematous and analgesic effects, early restoration of impaired functions, and the time of wound healing process reaches that of healing by primary tension, which allows us to reduce the number of medications, as well as treatment and rehabilitation time.

Frequency-Dependent Squeezed Vacuum Source for the Advanced Virgo Gravitational-Wave Detector.

In this Letter, we present the design and performance of the frequency-dependent squeezed vacuum source that will be used for the broadband quantum noise reduction of the Advanced Virgo Plus gravitational-wave detector in the upcoming observation run. The frequency-dependent squeezed field is generated by a phase rotation of a frequency-independent squeezed state through a 285m long, high-finesse, near-detuned optical resonator. With about 8.5dB of generated squeezing, up to 5.6dB of quantum noise suppression has been measured at high frequency while close to the filter cavity resonance frequency, the intracavity losses limit this value to about 2dB. Frequency-dependent squeezing is produced with a rotation frequency stability of about 6Hz rms, which is maintained over the long term. The achieved results fulfill the frequency dependent squeezed vacuum source requirements for Advanced Virgo Plus. With the current squeezing source, considering also the estimated squeezing degradation induced by the interferometer, we expect a reduction of the quantum shot noise and radiation pressure noise of up to 4.5dB and 2dB, respectively.

Integrated system model of spray flash vacuum distillation with internal heat recovery

This study proposed an integrated system model for an original spray flash vacuum distillation system that enhances and leverages the thermal non-equilibrium of the flash process via active vapor extraction to realize an internal heat recovery feature, in which partial heat from hotter vapor is recovered to cooler spray residue within the same stage of feed circulation. This system contains four interlinked sub-systems: (1) an evaporation chamber in which a vacuum-promoted spray flash vaporization occurs, with an active vapor extraction and an outflow of evaporation-cooled brine, (2) a recirculation loop of feed-brine mixture, with the circulation pump, feed heater, and spray nozzle, (3) a hybrid dual-condenser combination, with the internal heat recovery from condensing vapor to the recirculating feed and a secondary cooling by an external coolant, and (4) a vacuum source that maintains vacuum conditions to the entire system as well as discharges the non-condensable gases. The pressure of vapor phase, as the major interlinked operation parameter, is in order of sequential decrease from the evaporation chamber, through condensers, to the vacuum source while the depressurization level in each sub-system is strongly coupled with other transport characteristics such as flash vapor generation in the evaporation chamber or condensing vapor flow in condensers. Thus, the integrated system model is composed of four sub-models to describe the key processes in such four sub-systems. For the modeling validation, a lab-scale experimental system is developed to provide relevant measurements. Comparisons between model predictions against measurements show a good match. Major process characteristics (such as spray flash rate, yield rate, and operating temperatures and pressures) and operational thermodynamic characteristics (such as thermal consumption and heat recovery efficiency) are investigated parametrically. The system's multivariate impacts concerning distillate yield rate and heat recovery effectiveness are also studied with varied operating parameters. Results indicate the pronounced thermal non-equilibrium feature arising from the spray flash process can be effectively utilized via the internal heat recovery design of our system to recover up to more than half of the heat from the yield vapor. Meanwhile, the developed system model can effectively analyze various operational and parametric effects, proving valuable for system design and optimized operation.

Place of Negative Pressure Therapy in the Management of Delabour: Case Report

Skin loss or cutaneous tissue loss (CTL) occurs when the skin is damaged and cannot be directly closed with sutures. Negative pressure therapy (NPT) has emerged as an essential therapeutic tool for promoting wound healing in high-risk surgical wounds or chronic wounds that do not heal spontaneously. NPT involves applying negative pressure to the wound using a specific dressing connected to a vacuum source. This technique can be used until adequate granulation tissue forms or conditions are met for surgical intervention. The case of a 35-year-old patient with extensive cutaneous tissue loss on the right lower limb due to a road traffic accident is presented. The patient underwent surgical debridement followed by negative pressure wound therapy, leading to satisfactory results and completes healing. Negative pressure therapy has revolutionized wound management and should be used in conjunction with conventional treatments, regularly reassessing its efficacy and discontinuing it when goals are achieved or complications arise. When used appropriately, NPT is an invaluable tool for clinicians and patients in achieving therapeutic objectives.

Pneumatic computers for embedded control of microfluidics.

Alternative computing approaches that interface readily with physical systems are well suited for embedded control of those systems. We demonstrate finite state machines implemented as pneumatic circuits of microfluidic valves and use these controllers to direct microfluidic liquid handling procedures on the same chip. These monolithic integrated systems require only power to be supplied externally, in the form of a vacuum source. User input can be provided directly to the chip by covering pneumatic ports with a finger. State machines with up to four bits of state memory are demonstrated, and next-state combinational logic can be fully reprogrammed by changing the hole-punch pattern on a membrane in the chip. These pneumatic computers demonstrate a framework for the embedded control of physical systems and open a path to stand-alone lab-on-a-chip devices capable of highly complex functionality.

Side-Channel-Secure Quantum Key Distribution with Imperfect Vacuum Sources

The side-channel-secure (SCS) quantum key distribution (QKD), SCS QKD has attracted much attention due to its higher security compared to the measurement-device-independent protocols. It is not only measurement-device-independent secure, but also secure against source-state side channels provided that Eve has no access to Alice's or Bob's setups inside their labs. In the original protocol for SCS QKD, the side channels and the intensities of the coherent sources are allowed to be different in different time windows, but the vacuum sources of Alice and Bob have to be perfect, which is impossible in practice due to the finite extinction ratio of the intensity modulators. In this paper, we present a method that does not need the perfect vacuum source requested by the original protocol and assures the result as secure as the original protocol. With the upper bounds of the amplitudes of the nonvacuum part of the sources, the secure key rate of our SCS QKD protocol here with imperfect vacuum and unstable sources can be calculated. The numerical results show that, the secure distance of the SCS QKD protocol exceeds 150 km, provided that the intensity of the imperfect vacuum source is less than ${10}^{\ensuremath{-}8}$, which can be achieved in the experiment by a two-stage intensity modulator, where we also show that the active odd-parity pairing method and standard pairing method using two-way classical communication can be applied to the SCS QKD protocol to improve the key rate. Given the side-channel security based on the existing technological level, this work makes it possible to realize side-channel-secure QKD with real devices.

Design of a Vacuum Independent, Power Assisted Brake by Wire System using a Novel Electro-Magnetic Brake Booster

With an increasing demand in the market towards electrical vehicles through technological advancements in the automotive field like, automated driving assistance that which have resulted in higher safety requirements and new innovations in the braking system, such as vacuum-independent, automated braking, and regenerative braking, play a crucial role in the vehicle's comfort and economics. However, the classic vacuum brake booster is no longer capable of meeting these requirements. A revolutionary Electro-Magnetic brake booster system is suggested in this research; this system is aimed to perform the function of boosting or enhancing the driver's pedal power despite remaining dependent on the vacuum source. Such an Electro-magnetic brake booster is mainly composed of an Electro-magnetic core plate, a ferromagnetic actuating plate and an ECU. It consumes electrical energy and converts into magnetic force to attract the metallic actuating plate, which is mechanically coupled to the pushrod of the master cylinder. However, the power required for braking (developing pressure in a master cylinder) is provided by the electrical power source. The core plate is associated with a pole as the electromagnet cores are mounted on one side of it. By incorporating a pedal pressure sensor linked to the ECU, which can control the electric power input to this core plate. Thus, the magnetic force developed is used in pulling the Actuating plate. In turn, it builds up the required pressure in the master cylinder. This novel Electro-Magnetic brake booster can be a better solution to satisfy the drawbacks of the existing brake boosters such as complexity in the structure and mechanism. Thus, this brake booster can be joined in substantial vehicles, autos and can be utilized as driver brake assistance for future Electric Vehicles by making a few upgrades in the ECU and the servo.
 

Compliant Suction Gripper With Seamless Deployment and Retraction for Robust Picking Against Depth and Tilt Errors

Applying suction grippers in unstructured environments is a challenging task because of depth and tilt errors in vision systems, requiring additional costs in elaborate sensing and control. To reduce additional costs, suction grippers with compliant bodies or mechanisms have been proposed; however, their bulkiness and limited allowable error hinder their use in complex environments with large errors. Here, we propose a compact suction gripper that can pick objects over a wide range of distances and tilt angles without elaborate sensing and control. The spring-inserted gripper body deploys and conforms to distant and tilted objects until the suction cup completely seals with the object and retracts immediately after, while holding the object. This seamless deployment and retraction is enabled by connecting the gripper body and suction cup to the same vacuum source, which couples the vacuum picking and retraction of the gripper body. Experimental results validated that the proposed gripper can pick objects within 79 mm, which is 1.4 times the initial length, and can pick objects with tilt angles up to 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> . The feasibility of the gripper was verified by demonstrations, including picking objects of different heights from the same picking height and the bin picking of transparent objects.

Automated cellular stimulation with integrated pneumatic valves and fluidic capacitors.

Microfluidic technologies have proven to be a reliable tool in profiling dynamic insulin secretion from islets of Langerhans. Most of these systems rely on external pressure sources to induce flow, leading to difficulties moving to more elaborate systems. To reduce complexity, a microfluidic system was developed that used a single vacuum source at the outlet to drive fluidic transport of immunoassay reagents and stimulation solutions throughout the device. A downside to this approach is the lack of flow control over the reagents delivered to the islet chamber. To address this challenge, 4-layer pneumatic valves were integrated into the perfusion lines to automate and control the delivery of stimulants; however, it was found that as the valves closed, spikes in the flow would lead to abnormal insulin secretion profiles. Fluidic capacitors were then incorporated after the valves and found to remove the spikes. The combination of the valves and capacitors resulted in automated collection of insulin secretion profiles from single murine islets that were similar to those previously reported in the literature. In the future, these integrated fluidic components may enable more complex channel designs to be used with a relatively simple flow control solution.

Differences in fluid removal of different open-pore elements for endoscopic negative pressure therapy in the upper gastrointestinal tract

Endoscopic negative pressure therapy is an effective treatment strategy for various defects of the gastrointestinal tract. The functional principle is based on an open-pore element, which is placed around a perforated drainage tube and connected to a vacuum source. The resulting open-pore suction device can undergo endoluminal or intracavitary placement. Different open-pore suction devices are used for endoscopic negative pressure therapy of upper gastrointestinal tract defects. Comparative analyses for features and properties of these devices are still lacking. Eight different (six hand-made devices and two commercial devices) open-pore suction devices for endoscopic negative pressure therapy of the upper gastrointestinal tract were used, amount fluid removed was evaluated. The evaluation parameters included the time to reach the target pressure, the time required to remove 100 ml of water, and the material resistance of the device. All open-pore suction devices are able to aspirate the target volume of fluids. The time to reach the target volume varied considerably. Target negative pressure was not achieved with all open-pore suction devices during the aspiration of fluids; however, there was no negative effect on suction efficiency. Of the measurement data, material resistance could be calculated for six open-pore elements. We present a simple experimental, nonphysiologically setup for open-pore suction devices used for endoscopic negative pressure therapy. The expected quantity of fluids secreted into the treated organs should affect open-pore suction device for endoscopic negative pressure therapy.

Sending-or-not-sending twin field quantum key distribution with imperfect vacuum sources

The sending-or-not-sending (SNS) protocol of the twin-field (TF) quantum key distribution (QKD) can tolerant large misalignment error and its key rate can exceed the linear bound of repeaterless QKD. The original SNS protocol and all variants of TF-QKD require perfect vacuum sources, but in the real world experiments there is no practical perfect vacuum source. Instead, experimenters use extremely weak sources to substitute vacuum sources, which may break the security of the protocol. Here we propose an SNS protocol with imperfect vacuum sources and give the non-asymptotic decoy-state analysis of this protocol. Our numerical simulation shows that when the imperfect vacuum sources are close to perfect vacuum sources, our protocol can obtain similar key rate as that with perfect vacuum sources. This is the first result that closes the potential security loophole due to imperfect vacuum of TF-QKD.

3D Printed Instrument for Taylor Dispersion Analysis with Two-Point Laser-Induced Fluorescence Detection.

Precisely controlling the size of engineered biomolecules and pharmaceutical compounds is often critical to their function. Standard methods for size characterization, such as dynamic light scattering or size exclusion chromatography, can be sample intensive and may not provide the sensitivity needed for mass- or concentration-limited biological systems. Taylor dispersion analysis (TDA) is a proven analytical method for direct, calibration-free size determination which utilizes only nL-pL sample volumes. In TDA, diffusion coefficients, which are mathematically transformed to hydrodynamic radii, are determined by characterizing band broadening of an analyte under well-controlled laminar flow conditions. Here, we describe the design and development of a 3D printed instrument for TDA, which is the first such instrument to offer dual-point laser-induced fluorescence (LIF) detection. The instrument utilized a fully 3D printed eductor as a vacuum source for precise and stable pressure-driven flow within a capillary, evidenced by a linear response in generated static pressure to applied gas pressure (R2 = 0.997) and a 30-fold improvement in stability of static pressure (0.05% RSD) as compared to a standard mechanical pump (1.53%). Design aspects of the LIF detection system were optimized to maximize S/N for excitation and emission optical axes, and high sensitivity was achieved as evidenced by an 80 pM limit of detection for the protein R-Phycoerythrin and low nM limits of detection for three additional fluorophores. The utility of the instrument was demonstrated via sizing of R-Phycoerythrin at pM concentrations.

Hand-powered vacuum-driven microfluidic gradient generator for high-throughput antimicrobial susceptibility testing

The growth of bacterial resistance to antimicrobials is a serious problem attracting much attention nowadays. To prevent the misuse and abuse of antimicrobials, it is important to carry out antibiotic susceptibility testing (AST) before clinical use. However, conventional AST methods are relatively laborious and time-consuming (18–24 h). Here, we present a hand-powered vacuum-driven microfluidic (HVM) device, in which a syringe is used as the only vacuum source for rapid generating concentration gradient of antibiotics in different chambers. The HVM device can be preassembled with various amounts of antibiotics, lyophilized, and stored for ready-to-use. Bacterial samples can be loaded into the HVM device through a simple suction step. With the assistance of Alamar Blue, the AST assay and the minimum inhibitory concentration (MIC) of different antibiotics can be investigated by comparing the growth results of bacteria in different culture chambers. In addition, a parallel HVM device was proposed, in which eight AST assays can be performed simultaneously. The results of MIC of three commonly used antibiotics against E. coli K-12 in our HVM device were consistent with those obtained by traditional method while the detection time was shortened to less than 8 h. We believe that our platform is high-throughput, cost-efficient, easy to use, and suitable for POCT applications.

Effect of the Laser Pulse Width in MALDI-2: A Comparative Study of Picosecond versus Nanosecond Wide Pulses for Laser Postionization.

MALDI-2 is a recently introduced technique for postionization (PI) in matrix-assisted laser desorption/ionization (MALDI). It is based on an initial photoionization of neutrally desorbed matrix molecules and subsequent charge-transfer reactions in a fine vacuum or atmospheric pressure ion source. MALDI-2 significantly increases the ion yields for numerous classes of analytes, including lipids, glycans, and a range of pharmaceuticals. To obtain insights into the ionization mechanisms underlying the primary step of PI in MALDI-2, we here conducted a set of experiments with two lasers at 266 nm wavelength and pulse durations of 28 ps and 6 ns, respectively, on a modified orthogonal-extracting time-of-flight mass spectrometer (QTOF, Synapt). 2,5-Dihydroxybenzoic acid (DHB) and 2,5-dihydroxyacetophenone (DHAP) were investigated as MALDI matrices in the positive-ion mode with standardized lipid samples. Analyte- and matrix-derived ion signals were recorded as a function of PI laser pulse energies. The ion signal intensity displays a quadratic dependency on PI-laser pulse energy for low to moderate intensities of up to ∼107 W/cm2. This behavior suggests the involvement of resonance enhanced two-photon ionization (REMPI) of neutral matrix molecules in the ionization pathways. Comparing nanosecond and picosecond pulses at the same PI laser pulse energy, higher photon density produced by the shorter pulses generally produced sizably higher ion signal intensities, also corroborating an involvement of REMPI-like processes. Based on a theoretical description of the MALDI-2 process derived from prevalent REMPI theory, comparative measurements allow us to determine the lifetime of the excited states of the employed matrices. Resulting values for both matrices are in good agreement with the literature and corroborate the REMPI-based approach.

Low-frequency fluorescence spectrum of a laser driven polar quantum emitter damped by squeezed vacuum with finite bandwidth

A two-level quantum emitter with broken inversion symmetry driven by external semiclassical monochromatic high-frequency electromagnetic (e.g., laser) field and damped by squeezed vacuum reservoir with finite bandwidth is presented. The squeezed vacuum source is assumed to be either degenerate parametric oscillator (DPO) or a non-degenerate parametric oscillator (NDPO). It is shown that the shape of low-frequency fluorescence spectrum of the emitter can be effectively alternated by controlling the degree of the squeezed vacuum source degeneration and phase of the squeezing.

Non-destructive DNA recovery from handwritten documents using a dry vacuum technique.

Investigations of many crimes such as robberies, kidnappings, and terrorism are often associated with the recovery of a paper document which has been written by the perpetrator. Paper can provide a variety of forensic evidence such as DNA, latent fingermarks, and indented writing. The focus of this study was DNA recovery from handwritten notes through a vacuum suction device while preserving the other evidence types and the integrity of the document. Copy paper was used to create handwritten documents and sheets with deliberate fingerprints, and indentations. The homemade vacuum device consists of a glass pipette blocked with a moistened swab and attached to a vacuum source. The method collected sufficient DNA amounts for DNA typing analysis with 80% of the 11 copy paper samples tested giving probative DNA profiles with five being eligible for DNA database entry. DNA recovery was also tested on other commonly encountered paper types. DNA quantities would have been sufficient for STR typing for approximately 50% of manila envelopes and notebook paper samples, but not for magazine pages and bank deposit slips. Deliberate sebaceous and eccrine latent fingermarks placed onto copy paper and developed with magnetic fingerprint developer or 1,2 indanedione were not affected by the vacuum swabbing technique. Simulated robbery notes with indented writing and processed using an Electrostatic Detection Apparatus (ESDA) demonstrated no interference through the DNA collection. This vacuum-based collection method enables laboratories to reverse the current questioned document workflow and start with DNA collection.