Pneumatic Micro Research Articles

Osteoregenerative Potential of 3D-Printed Poly ε-Caprolactone Tissue Scaffolds In Vitro Using Minimally Manipulative Expansion of Primary Human Bone Marrow Stem Cells.

The repair of orthopedic and maxillofacial defects in modern medicine currently relies heavily on the use of autograft, allograft, void fillers, or other structural material composites. This study examines the in vitro osteo regenerative potential of polycaprolactone (PCL) tissue scaffolding, fabricated via a three-dimensional (3D) additive manufacturing technology, i.e., a pneumatic micro extrusion (PME) process. The objectives of this study were: (i) To examine the innate osteoinductive and osteoconductive potential of 3D-printed PCL tissue scaffolding and (ii) To perform a direct in vitro comparison of 3D-printed PCL scaffolding with allograft Allowash® cancellous bone cubes with regards to cell-scaffold interactions and biocompatibility with three primary human bone marrow (hBM) stem cell lines. This study specifically examined cell survival, cell integration, intra-scaffold cell proliferation, and differentiation of progenitor cells to investigate the potential of 3D-printed PCL scaffolds as an alternative to allograft bone material for the repair of orthopedic injuries. We found that mechanically robust PCL bone scaffolds can be fabricated via the PME process and the resulting material did not elicit detectable cytotoxicity. When the widely used osteogenic model SAOS-2 was cultured in PCL extract medium, no detectable effect was observed on cell viability or proliferation with multiple test groups showing viability ranges of 92.2% to 100% relative to a control group with a standard deviation of ±10%. In addition, we found that the honeycomb infill pattern of the 3D-printed PCL scaffold allowed for superior mesenchymal stem-cell integration, proliferation, and biomass increase. When healthy and active primary hBM cell lines, having documented in vitro growth rates with doubling times of 23.9, 24.67, and 30.94 h, were cultured directly into 3D-printed PCL scaffolds, impressive biomass increase values were observed. It was found that the PCL scaffolding material allowed for biomass increase values of 17.17%, 17.14%, and 18.18%, compared to values of 4.29% for allograph material cultured under identical parameters. It was also found that the honeycomb scaffold infill pattern was superior to the cubic and rectangular matrix structures, and provided a superior microenvironment for osteogenic and hematopoietic progenitor cell activity and auto-differentiation of primary hBM stem cells. Histological and immunohistochemical studies performed in this work confirmed the regenerative potential of PCL matrices in the orthopedic setting by displaying the integration, self-organization, and auto-differentiation of hBM progenitor cells within the matrix. Differentiation products including mineralization, self-organizing "proto-osteon" structures, and in vitro erythropoiesis were observed in conjunction with the documented expression of expected bone marrow differentiative markers including CD-99 (>70%), CD-71 (>60%), and CD-61 (>5%). All of the studies were conducted without the addition of any exogenous chemical or hormonal stimulation and exclusively utilized the abiotic and inert material polycaprolactone; setting this work apart from the vast majority of contemporary investigations into synthetic bone scaffold fabrication In summary, this study demonstrates the unique clinical potential of 3D-printed PCL scaffolds for stem cell expansion and incorporation into advanced microstructures created via PME manufacturing to generate a physiologically inert temporary bony defect graft with significant autograft features for enhanced end-stage healing.

Design and characterization of a pneumatic micro glass beads matrix sensor for soil water potential threshold control in irrigation management

Soil moisture porous matrix sensors may be good alternatives to tensiometers for measuring soil–water matric potential (SMP) for irrigation scheduling based on soil–water status approaches. The objective of this paper is to present and evaluate a new porous matrix sensor (IGstat) for detecting specific SMP thresholds for possible application in irrigation scheduling regulated by the SMP threshold concept. The IGstat sensor uses a non-sintered, glass bead microspheres (microGB) core and an outer ceramic cup, having larger air bubbling pressure (BP), to establish hydraulic contact with the soil. Pneumatic, optical, or electrical properties of the microGB porous medium can be then measured to infer the SMP. This paper describes and evaluates the performance of IGstat sensors for SMP threshold detection, using the pneumatic mode with a small air flow applied and air pressure monitored in the sensor tubing. Five IGstat sensors were built with different microGB diameters (15–125 µm) having air BP varying from 6 to 40 kPa. A power function was fitted to the data, which can be used to select microGB diameters to build IGstat sensors of required air BP. The experimental setup proposed to determine the sensor BP by incremental air injection provided air BP values in good agreement with those observed in a soil evaporation experiment (average relative error of 7.6%). The sensor responses in soil, with a small air pressure applied to them, showed a sharp pressure decreases when the SMP approached the sensor air BP, decreasing to about zero for SMP equal to the sensor air BP. The proposed sensors and approach showed potential for irrigation scheduling.

A microphysiological system to investigate the pressure dependent filtration at an artificial glomerular kidney barrier

Abstract Chronic kidney disease (CKD) is a global health problem that affects around 11 to 13% of the world’s population and more than 18% of European citizens. Characteristic syndromes of CKD during all stages of the disease are proteinuria and ongoing glomerular dysfunction caused by cellular damages at the glomerular filtration barrier. While some rare cases of the disease are correlated to genetic depositions the majority of cases are caused by diabetes, glomerulosclerosis, high blood pressure and glomerulonephritis. Thus, recapitulating the interplay of high blood pressure and changes at the glomerular filtration barrier in vitro seems an adequate way to mimic CKD. Here we present a microphysiological system of the glomerular filter that is capable to simulate high blood pressure at the glomerular filtration barrier in vitro. It consists of a closed loop microfluidic circuit with an integrated pneumatically driven heart like micro pump that constantly circulates the cell culture media at the blood site of the glomerular barrier. The ThinCert™ insert could be reversibly integrated into a holder system that ensures the correct position of the insert within the microfluidic circuit. By using different modulations of the integrated pneumatic micro pump different physiological and pathophysiological conditions e.g. hypertonic stress, like in CKD, could be applied. The influence of hypertonic conditions on the filtration above the barrier was studied by changes of TEER values and measurement of the flux of fluorescent labelled albumin through the cellular barrier.

2A2-C03 熱応答性流体バルブとその圧力駆動アクチュエータへの一体化

In this study, we propose a novel micro valve usingPluronic^[○!R] F127 as thermally responsive solution. It was hard to integrated conventional micro valves into micro devices because of their complicated composition. Thus, we propose novel micro valve to be integrated with pneumatic micro actuator. The thermally responsive solution valve was designed and fabricated by using micro channel containing thermally responsive solution with micro heater. The micro valve can be reversibly driven by heating and gellirig of thermally responsive solution. Furthermore,we integrated the micro valve topneumatic balloon actuator and successfully controlled its actuation by developed micro valve. Integration of a valve into pneumatic actuator allows designing compact pneumatic actuator system.

Analysis and Experiment on the Response Characteristics of a Pneumatic Micro Actuator Based on TBC Model

Using basic physical arguments, we present a design and method for the fabrication of a pneumatic micro PDMS actuator using multilayer soft lithography based on dry-film photoresist. Its novel structure consists of a three-way electromagnetic microvalve for gas flow control which is connected with gas inlet microchannel for the actuator. Then the whole system is considered as a throttle blind capacitor (TBC) model and it is used to predict the response time of the pneumatic actuator by correlating its characteristics such as gas pressurizing, air resistance and membrane deformation. For this micro actuator, upward deformation motions of actuated area are observed of actuated area under 100KPa (N2) pressure and the fast open response (~ 15 ms) was achieved at 50KPa pressure. Our method provides a simple, cheap and save-time pneumatic micro actuator which can be used in active functions, such as valves, pumps and mixers integrated on pneumatic microfluidic chips for downsizing the driving pressure and improving the whole efficiency of microchips.

Pneumatic Micro Dispenser System for Ubiquitous Microchemical Devices

This paper describes the development of the pneumatic micro dispenser system for ubiquitous microchemical devices, such as health care devices. The pressurization and decompression switchable micropump chip, the dispenser chip, and the 10-directional switching valve chip are developed successfully as components of this system. This system assembled with these chips can divide liquids into approximately 0.5 µl samples if its disk is simply rotated manually, and the system can be reused by simply replacing the dispenser chip where the sample exits.

1P1-V09 空気圧駆動マイクロ分注チップによる分配操作の検証(ナノ・マイクロ流体システム)

The pneumatic micro dispenser chip that can divide liquids into 10nL each has been developed successfully. From the dispensing experimental result, it was difficult to supply the divided liquid properly to the channel (reactor) selected among branched channels. Therefore, we found out that the issue was caused by the air compression in the micro channel. The design of the dispenser chip to supply the divided liquid properly to the reactor was improved. The experimental result provided us the effectiveness of the improvement. The micro dispenser chip with manipulation of nanoliter volume is useful for portable health care devices.

P-G1-11 多分岐分配可能な空気圧駆動マイクロ分注チップの開発(P-G1 マイクロ熱流体,ポスターセッション論文)

We verified about the multiple distribution method to supply the divided sample to the channel selected among the branched channels. The pneumatic micro dispenser chip that can divide liquids into 10nL each has been developed successfully. From the dispensing experimental result, the problem that it is difficult to supply the divided liquid properly to the channel (reactor) selected among branched channels has occurred. Therefore, we investigated that the issue was caused by the air compression in the micro channel and The dispenser chip was improved in order to supply the divided liquid properly to micro channel. The experimental result using improved chip provided us the effectiveness of the improvement. The micro dispenser chip with manipulation of nanoliter volume is useful for portable health care devices.

Poly(dimethylsiloxane) microchip-based immunoassay with multiple reaction zones: Toward on-chip multiplex detection platform

In this work, a poly(dimethylsiloxane) (PDMS) microchip-based immuno-sensing platform with integrated pneumatic micro valves is described. The microchip was fabricated with multiple layer soft lithography technology. By controlling the activation status of corresponding valves, reagent flows in the microchannel network can be well manipulated so that immuno-reactions only take place at designated reaction zones (DRZs). Four DRZs are included in the prototype microchip. Since these DRZs are all isolated from each other by micro valves, cross contamination is prevented. Using the inner surface of the all-PDMS microchannel as immunoassay substrate, on-chip sandwich format solid phase immunoassay was performed to demonstrate the feasibility of this immuno-sensing platform. Mouse IgG and fluorescein isothiocyanate (FITC) were used as the model analyte and the signal reporter respectively. Only 10 μl sample is needed for the assay and low detection limit of 5 ng/ml (≈33 pM) was achieved though low-cost polyclonal antibodies were used in our experiment for feasibility study only. Much lower detection limit may easily be achieved by using high quality monoclonal antibodies. Through a simple yet effective comparison experiment, it was also found that high concentration BSA blocking solution (5% BSA in PBS buffer) can effectively suppress the non-specific binding in the surface of the microfluidic channels. The encouraging results from mouse IgG immunoassay proved the feasibility of our microchip design. With slight modification of the assay protocol, the same chip design can be used for multi-target detection and can provide a simple, cost-effective and integrated microchip solution for multiplex immunoassay applications.

The self-generated peristaltic motion of cascaded pneumatic actuators for micro pumps

This paper presents a new actuation mechanism for the self-generated peristaltic motion of cascaded actuators and its application to micro pumps. The operational method is based on the fluidic circuit of an elastic tube. The elastic tube is modeled as a ladder network consisting of fluidic resistances in series and fluidic capacitances in parallel like multi-stage low-pass filters in an electrical circuit. All segments of the lumped model of the elastic tube have different dynamic characteristics because their time constants are different. In other words, all segments should be deformed sequentially like peristaltic motion. This phenomenon has good potential to cause peristaltic motion of the cascaded actuators in response to the application of single-phase pneumatic signals. Analogues between the electrical and fluidic circuits were applied to a pneumatic micro pump with a micro fluidic channel and three pneumatic actuators connecting a unique micro channel for supplying the compressed air. The polymeric micro pumps were fabricated with soft lithography using only polyimethylsiloxsane. The proposed working principle was verified through simulation of the static deformation of the cascaded actuator diaphragms and the actuator, as well as tested experimentally. The dual operational modes of the proposed device (i.e., rubber-seal valve and peristaltic pumping mode) were also verified and successfully demonstrated in a liquid pumping test of the single and double pumps.

Batch fabrication of micro grippers with integrated actuators

In this paper we present improvements in the field of batch fabricated micro grippers with shape memory alloy (SMA) actuators or pneumatic drives. In this context we illustrate two methods of structuring SMA foils. Moreover, it is shown how the processed SMA elements can be embedded into monolithic SU-8 grippers. We also describe actuator elements for silicon/SU-8 hybrid micro grippers. Furthermore, we report on the advantages of pneumatic micro grippers and how this alternative actuation principle can be fabricated in batch technology. In this regard, a thermoplastic adhesive electrodepositing process is presented.

Multi-physics system modeling of a pneumatic micro actuator

We present a first step in the conception of a micro pressure source. It consists in three main parts: (i) a heating resistance built on a dielectric membrane, (ii) air encapsulated at atmospheric pressure and (iii) an elastomer membrane with high elastic properties. A PDMS-based material is chosen as the membrane material for its elastic properties. When the actuation is required, air is heated to increase its pressure; the gain in pressure produces the deformation of the elastic membrane. Physical models have been developed for each step of operation: the heating of the resistance, the air pressurization and the elastic membrane deformation. An important model feature is the coupling of air pressurization with membrane deformation. This paper presents each individual model that has been correlated with experimental results. Then, all the models are implemented into one system model used to predict the actuator performance as a function of input electrical signal.

A pneumatic micro cell chip for the differentiation of human mesenchymal stem cells under mechanical stimulation

A new micro cell chip which can induce stem cells to differentiate into specific body cell types has been designed and fabricated for tissue engineering. This paper presents the test results of a micro cell stimulator which can provide a new miniaturized tool in cell stimulation, culture and analysis for stem cell research. The micro cell stimulator is designed to apply compressive pressure to the hMSCs (human mesenchymal stem cells) for inducing osteogenesis. The micro cell stimulator is based on the pneumatic actuator with a flexible diaphragm which consists of an air chamber and cell chambers. The hMSCs under cyclic compressive stimulation for one week were observed and assessed by monitoring CD90 (Thy-1), actin, alkaline phosphatase (ALP) and alizarin red expression. The results suggest that cyclic mechanical stimulation is attributed to the different phenomenon of cultured hMSCs in cell proliferation and differentiation. These results are important for the feasibility of the micro cell stimulator to provide the reduction of the necessary quantity of cells, process cost and the increase of the throughput.

1P1-N02 空気圧駆動マイクロ分注システムの開発(MEMSとナノテクノロジー)

The pneumatic micro dispenser system without any dead volume of sample was proposed. The sampling chip and the 10-directional switching valve chip as the component of this dispenser were developed successfully. The sampling chip succeeded to divide liquid every 1μL or 0.5μL without any dead volume of sample only by the decompression and the pressurization operation of the air, due to the novel detecting method of micro fluid and check valves of hat shape. The switching valve chip selects the outlet that injects the dispensed sample. This chip succeeded to switch ten outlets by built-in solenoid (1N,6VDC) under high leakage pressure (≧500kPa).

Development of the pneumatic valve with bimorph type PZT actuator

The benefits of the pneumatic valve with bimorph type piezoelectric (PZT) actuator are faster response times, low energy consumption, and the ability to be used in hazardous environments and field bus systems. In order to develop a PZT actuator system for the pneumatic valve, bimorph type PZT actuator (length: 25.2 mm, width: 7.2 mm, thickness: 0.5 mm) using the softener type PZT with constant of −220 × 10 −12 C N −1, carbon plate as a shim and its controller circuit (operating voltage range: 24 V, built-in fast recovery diode) were suggested and investigated. Performance tests and characteristics analysis, such as displacement, force, hysteresis and frequency properties, were carried out. The displacement of the actuator measured at the end point was 63 μm, force of the actuator was 0.052 N and maximum operating frequency was 15 Hz. Also, characteristics of the pneumatic valve with PZT actuator were evaluated in a testing system. The results show that the suggested PZT actuator is suitable for pneumatic micro valve.

Vapor−Liquid−Liquid Equilibria, Azeotropic, and Excess Enthalpy Data for the Binary System n-Undecane + Propionamide and Pure-Component Vapor Pressure and Density Data for Propionamide

Vapor−liquid−liquid equilibria (VLLE), azeotropic, and excess enthalpy (HE) data for the binary system n-undecane + propionamide were measured at temperatures from 359.25 to 416.65 K. Additionally, pure-component vapor pressure and density data for propionamide were determined experimentally. The LLE and VLLE measurements were performed in a stirred glass cell and in a static equilibrium cell with a capability to take small samples from the different phases by using pneumatic micro samplers. For the HE measurements, an isothermal flow calorimeter was used, and the azeotropic data were obtained from distillation experiments using a micro spinning band column. The pure-component vapor pressures and densities were measured with the help of the dynamic method (ebulliometer) and a vibrating tube densimeter, respectively. To the experimental mixture data from this work linear temperature-dependent interaction parameters for the NRTL model were fitted. They can be used to represent the phase equilibrium behavior and excess enthalpies of the investigated system.

Comparison of several spray chambers operating at very low liquid flow rates in inductively coupled plasma atomic emission spectrometry.

Four different spray chambers were evaluated in ICP-AES at very low liquid flow rates: a double-pass (Scott type), a conventional cyclonic, and two low-volume cyclonic-type spray chambers (i.e., Cinnabar and Genie). A glass concentric pneumatic micro nebulizer (Atom Mist) was used in conjunction with all four chambers. The liquid flow rate was varied from 10 to 160 microL min(-1). The conventional cyclonic spray chamber gave rise to coarser tertiary aerosols, higher analyte and solvent transport rates, higher sensitivity and lower limits of detection than the remaining ones. The low-volume spray chambers afforded analytical figures of merit similar to the double-pass one, despite their very different designs. However, these spray chambers exhibited shorter wash-out times. The matrix effects were significant only for the double-pass. This fact allowed the analysis of reference samples by employing aqueous standards at a minimum level of sample consumption. The recoveries obtained for the cyclonic spray chambers and several certified samples were close to 100%, being always lower in the case of the double-pass spray chamber.