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We present a novel 3D printed Microfluidic Actuation System for lateral flow assay in low resource settings. The system is used to deliver reagents for multi-step assays from blisters placed into cavities in the 3D printed assembly. The system is operated by manually depressing the blister housing and rotating to the next blister location. This is repeated for each step in the assay to enable a simple and repeatable method of delivering specified volumes to the assay at arbitrary time intervals as required by the assay. The blisters provide for robust storage while maintaining consistent aliquots for the assay. We characterize the percent of the total volume delivered to the lateral flow assay from the blisters including the volume dispensed at given time intervals.

The salient features of microfluidics such as reduced cost, handling small sample and reagent volumes and less time required to fabricate the devices has inspired the present work. The incompatibility of three-dimensional printer resins in their native form and the method to improve their compatibility to many biological processes via surface modification are reported. The compatibility of the material to build microfluidic devices was evaluated in three different ways: (i) determining if the ultraviolet (UV) cured resin inhibits the polymerase chain reaction (PCR), i.e. testing devices for PCR compatibility; (ii) observing agglutination complex formed on the surface of the UV cured resin when anti-C-reactive protein (CRP) antibodies and CRP proteins were allowed to agglutinate; and (iii) by culturing human embryonic kidney cell line cells and testing for its attachment and viability. It is shown that only a few among four in its native form could be used for fabrication of microchannels and that had the least effect on biological molecules that could be used for PCR and protein interactions and cells, whereas the others were used after treating the surface. Importance in building lab-on-chip/micrototal analysis systems and organ-on-chip devices is found.

Microfluidics has advanced in terms of design and structures; however, fabrication methods are time-consuming or expensive relative to facility costs and equipment needed. This work demonstrates a fast and economically viable 2D/3D maskless digital light-projection method based on a stereolithography process. Unlike other fabrication methods, one exposure step is used to form the whole device. Flash microfluidics is achieved by incorporating bonding and channel fabrication of complex structures in just 2.5 s to 4 s and by fabricating channel heights between 25 μm and 150 μm with photopolymer resin. The features of this fabrication technique, such as time and cost saving and easy fabrication, are used to build devices that are mostly needed in microfluidic/lab-on-chip systems. Due to the fast production method and low initial setup costs, the process could be used for point of care applications.

In this work, we present for the first time, the use of a simple fractal capacitive biosensor for the quantification and detection of sex-determining region Y (SRY) genes. This section of genetic code, which is found on the Y chromosome, finds importance for study as it causes fetuses to develop characteristics of male sex-like gonads when a mutation occurs. It is also an important genetic code in men, and disorders involving the SRY gene can cause infertility and sexual malfunction that lead to a variety of gene mutational disorders. We have therefore designed silicon-based, label-free fractal capacitive biosensors to quantify various proteins and genes. We take advantage of a good dielectric material, Parylene C for enhancing the performance of the sensors. We have integrated these sensors with a simple microchannel for easy handling of fluids on the detection area. The read-out value of an Agilent LCR meter used to measure capacitance of the sensor at a frequency of 1 MHz determined gene specificity and gene quantification. These data revealed that the capacitance measurement of the capacitive biosensor for the SRY gene depended on both the target and the concentration of DNA. The experimental outcomes in the present study can be used to detect DNA and its variations in crucial fields that have a great impact on our daily lives, such as clinical and veterinary diagnostics, industrial and environmental testing and forensic sciences.

In this paper, we report a simple method to evaluate biocompatibility of solid UV cross-linked resin as a material for microfluidic devices that can be used for biological applications. We evaluated the biocompatibility of the material in two different ways (1) determining if the UV cured resin inhibits the polymerase chain reaction (PCR) and (2) observing agglutination complex formed on the surface of the UV cured resin when anti-CRP antibodies and C- reactive protein (CRP) proteins were allowed to agglutinate. Six different types of 3D printer resins were compared to test the biocompatibility. The study showed that only few among them could be used for fabrication of micro channels and that had least effect on biological molecules that could be used for PCR and protein interactions. Through these studies it is possible to estimate the curing time of various resin and their type of interaction with biomolecules. This study finds importance in on-chip tissue engineering and organ-on-chip applications.

This paper proposes a new “twisted” 3D microfluidic mixer fabricated by a laser writing/microfabrication technique. Effective and efficient mixing using the twisted micromixers can be obtained by combining two general chaotic mixing mechanisms: splitting/recombining and chaotic advection. The lamination of mixer units provides the splitting and recombination mechanism when the quadrant of circles is arranged in a two-layered serial arrangement of mixing units. The overall 3D path of the microchannel introduces the advection. An experimental investigation using chemical solutions revealed that these novel 3D passive microfluidic mixers were stable and could be operated at a wide range of flow rates. This micromixer finds application in the manipulation of tiny volumes of liquids that are crucial in diagnostics. The mixing performance was evaluated by dye visualization, and using a pH test that determined the chemical reaction of the solutions. A comparison of the tornado-mixer with this twisted micromixer was made to evaluate the efficiency of mixing. The efficiency of mixing was calculated within the channel by acquiring intensities using ImageJ software. Results suggested that efficient mixing can be obtained when more than 3 units were consecutively placed. The geometry of the device, which has a length of 30 mm, enables the device to be integrated with micro total analysis systems and other lab-on-chip devices.

In this study, the EEG signals of major depression (MD) patients and healthy control subjects were investigated using different chaotic features. The acquired signals during 3 minutes were compared using complexity measures such as Katz fractal, Higuchi fractal dimension, Lempel-Ziv complexity (LZC) and Kolmogorov complexity (KC) in MATLAB between two groups. In order to determine which complexity measure is more effective in discriminating MD patients from control subjects, statistical variance analyses were performed. As a result, it was found that patients had increased EEG complexity and better discrimination were obtained using the LZC and KC.

Major depressive disorder (MDD) is a psychiatric mood disorder characterized by cognitive and functional impairments in attention, concentration, learning and memory. In order to investigate and understand its underlying neural activities and pathophysiology, EEG methodologies can be used. In this study, we estimated the nonlinearity features of EEG in MDD patients to assess the dynamical properties underlying the frontal and parietal brain activity. EEG data were obtained from 16 patients and 15 matched healthy controls. A wavelet-chaos methodology was used for data analysis. First, EEGs of subjects were decomposed into 5 EEG sub-bands by discrete wavelet transform. Then, both the Katz's and Higuchi's fractal dimensions (KFD and HFD) were calculated as complexity measures for full-band and sub-bands EEGs. Last, two-way analyses of variances were used to test EEG complexity differences on each fractality measures. As a result, a significantly increased complexity was found in both parietal and frontal regions of MDD patients. This significantly increased complexity was observed not only in full-band activity but also in beta and gamma sub-bands of EEG. The findings of the present study indicate the possibility of using the wavelet-chaos methodology to discriminate the EEGs of MDD patients from healthy controls.

BackgroundAlthough patients with major depressive disorder (MDD) have dysfunctions in cognitive behaviors and the regulation of emotions, the underlying brain dynamics of the pathophysiology are unclear. Therefore, nonlinear techniques can be used to understand the dynamic behavior of the EEG signals of MDD patients. MethodsTo investigate and clarify the dynamics of MDD patients' brains during different emotional states, EEG recordings were analyzed using nonlinear techniques. The purpose of the present study was to assess whether there are different EEG complexities that discriminate between MDD patients and healthy controls during emotional processing. Therefore, nonlinear parameters, such as Katz fractal dimension (KFD), Higuchi fractal dimension (HFD), Shannon entropy (ShEn), Lempel-Ziv complexity (LZC) and Kolmogorov complexity (KC), were computed from the EEG signals of two groups under different experimental states: noise (negative emotional content) and music (positive emotional content) periods. ResultsFirst, higher complexity values were generated by MDD patients relative to controls. Significant differences were obtained in the frontal and parietal scalp locations using KFD (p