Real-time monitoring and actuation of a hybrid siphon valve for hematocrit-independent plasma separation from whole blood.

Centrifugal microfluidics have emerged as a pivotal area of research spanning multiple domains, including medicine and chemistry. Among passive valving strategies, siphon valves have gained prominence due to their inherent simplicity and self-reliance, eliminating the need for external equipment. However, achieving optimal valve performance mandates supplementary elements like surface adjustments or pneumatic pressure. These introduce intricacies such as time-dependent behavior and augmented spatial demands. This research introduces inventive design and manufacturing methodologies to amplify siphon valve functionality. Our proposed innovation situates the siphon microchannel on the external surface of the primary chamber, linked via an inlet. The crux of novelty lies in the adaptable material selection for the microchannel's upper or lower surfaces, allowing the integration of hydrophilic materials such as glass or super hydrophilic coverslips, ensuring a leakage-free operation. Our approach offers a streamlined concept and manufacturing process, ensures consistent time-independent functionality, and accommodates the integration of multiple siphon valves within a solitary chamber, tailored for specific applications. Experimental evaluations validate a robust alignment between acquired data and analytical outcomes based on a modified equation. A customized disc is engineered, featuring four siphon valves meticulously calibrated for hematocrit (HCT) levels spanning from 20% to 50% at 10% intervals. Harnessing these valves yields a substantial surge in plasma separation efficiency, scaling up to 75%. Notably, this performance eclipses traditional single-valve reliant microfluidic methodologies, achieving a purity level exceeding 99% in plasma separation. These findings underscore the auspicious practical applicability of our proposed technique in plasma separation, fostering heightened platelet concentration, and expediting blood sample analysis.

Conceptual Design of a Device for Online Calibration of Spirometer Based on Neural Network.

Daily calibration of spirometry devices plays an important role in promoting the accuracy of pulmonary diagnostic results. It is needed to have more precise and adequate instruments for calibrating spirometry during the clinical use. In this work, a device was designed and developed based on a calibrated-volume syringe and an electrical circuit was also built to measure the air flux. Some colored tapes with specific size and order covered the syringe piston. When the piston moved in front of the color sensor, the input air flow was calculated according to the width of the strips and transferred to the computer. A Radial Basis Function (RBF) neural network estimator used new data to modify the previous estimation function for increasing the accuracy and the reliability. The simulation showed that the root mean square of the error improved from 13.7±0.37% to 4.2±0.22%, i.e. the calibration curve has improved about 70%.

A New Detection Chamber Design on Centrifugal Microfluidic Platform to Measure Hemoglobin of Whole Blood.

Undoubtedly, microfluidics has been a focal point of interdisciplinary science during the last two decades, resulting in many developments in this area. Centrifugal microfluidic platforms have good potential for use in point-of-care devices because they take advantage of some intrinsic forces, most notably centrifugal force, which obviates the need to any external driving forces. Herein, we introduce a newly designed detection chamber for use on microfluidic discs that can be employed as an absorbance readout step in cases where the final solution has a very low viscosity and surface tension. In such situations, our chamber easily eliminates the air bubbles from the final solution without any interruption. One microfluidic disc for measuring the hemoglobin concentration was designed and constructed to verify the correct functioning of this detection chamber. This disc measured the hemoglobin concentration of the blood samples via the HiCN method. Then, the hemoglobin concentration of 11 blood samples was quantified and compared with the clinic's data using the hemoglobin measurement disc, which included four hemoglobin measurement sets, and each set contained two inlets for the blood sample and the reagent, one two-part mixing chamber, and one bubble-free detection chamber. The measured values of the disc had good linearity and conformity compared with the clinic's data, and there were no air bubbles in the detection step. In this study, the standard deviation and the turnaround time were ± 0.51 g/dL and 68 s, respectively.

Development of simple and efficient Lab-on-a-Disc platforms for automated chemical cell lysis.

Cell lysis is the most important first step for molecular biology and diagnostic testing. Recently, microfluidic systems have attracted considerable attention due to advantages associated with automation, integration and miniaturization, especially in resource-limited settings. In this work, novel centrifugal microfluidic platforms with new configurations for chemical cell lysis are presented. The developed systems employ passive form of pneumatic and inertial forces for effective mixing of lysis reagents and cell samples as well as precise fluidic control. Characterizations of the developed Lab-on-a-Discs (LoaDs) have been conducted with dyed deionized (DI) waters and white blood cells (WBCs) to demonstrate the suitability of the proposed systems in terms of mixing, fluidic control and chemical cell lysis. By making comparison between the results of a well-established manual protocol for chemical cell lysis and the proposed chemical cell lysis discs, it has been proved that the developed systems are capable of realizing automated cell lysis with high throughput in terms of proper values of average DNA yield (ranging from 20.6 to 29.8 ng/µl) and purity (ranging from 1.873 to 1.907) as well as suitability of the released DNA for polymerase chain reaction (PCR). By considering the manual chemical lysis protocol as a reference, the efficiency of the LoaDs has been determined 95.5% and 91% for 10 min and 5 min lysis time, respectively. The developed LoaDs provide simple, efficient, and fully automated chemical cell lysis units, which can be easily integrated into operational on-disc elements to obtain sample-to answer settings systems.

The Effect of Moment of Inertia on the Liquids in Centrifugal Microfluidics.

The flow of liquids in centrifugal microfluidics is unidirectional and dominated by centrifugal and Coriolis forces (i.e., effective only at T-junctions). Developing mechanisms and discovering efficient techniques to propel liquids in any direction other than the direction of the centrifugal force has been the subject of a large number of studies. The capillary force attained by specific surface treatments, pneumatic energy, active and passive flow reciprocation and Euler force have been previously introduced in order to manipulate the liquid flow and push it against the centrifugal force. Here, as a new method, the moment of inertia of the liquid inside a chamber in a centrifugal microfluidic platform is employed to manipulate the flow and propel the liquid passively towards the disc center. Furthermore, the effect of the moment of inertia on the liquid in a rectangular chamber is evaluated, both in theory and experiments, and the optimum geometry is defined. As an application of the introduced method, the moment of inertia of the liquid is used in order to mix two different dyed deionized (DI) waters; the mixing efficiency is evaluated and compared to similar mixing techniques. The results show the potential of the presented method for pumping liquids radially inward with relatively high flow rates (up to 23 mm³/s) and also efficient mixing in centrifugal microfluidic platforms.

Fuzzy logic controller for hemodialysis machine based on human body model.

Fuzzy controllers are being used in various control schemes. The aim of this study is to adjust the hemodialysis machine parameters by utilizing a fuzzy logic controller (FLC) so that patient's hemodynamic condition remains stable during hemodialysis treatment. For this purpose, a comprehensive mathematical model of the arterial pressure response during hemodialysis, including hemodynamic, osmotic, and regulatory phenomena has been used. The multi-input multi-output (MIMO) fuzzy logic controller receives three parameters from the model (heart rate, arterial blood pressure, and relative blood volume) as input. According to the changes in the controller input values and its rule base, the outputs change so that the patient's hemodynamic condition remains stable. The results of the simulations illustrate that applying the controller can improve the stability of a patient's hemodynamic condition during hemodialysis treatment and it also decreases the treatment time. Furthermore, by using fuzzy logic, there is no need to have prior knowledge about the system under control and the FLC is compatible with different patients.