Cell transfection by electroporation is a biological assay that has been utilized to inject exogenous molecules (e.g.: RNA, DNA and protein) into live cells. Recently, electroporation has been utilized in developing cell therapy for cancer (e.g., CAR T-cell). One of the major drawbacks in current electroporation methods is the cell death during the process. These dead cells can be detrimental, if injected back to the patients. Current cell filtering methods are unable purify T-cells following electroporation, this is due to the lack of unique biomarkers that target the apoptosis and necrosis of T-cells. To address this issue, we have developed a method using dielectrophoresis and microfluidics, where no prior labeling is needed to isolate dead cells from live cells. Upon electroporation, the cell sample has to be flowed through the microfluidic chip where a selective electric field is applied through specially designed electrodes so that the dead cells are trapped on the electrodes, and the live cells are able to flow through and are collected at the end. Results after purification of the cells using our method reveal that it is possible to achieve ∼100% of purity in filtering of the live cells. This method presents a viable solution to a critical concern regarding CAR T-cell manufacturing. This paper presents an extended study of the variation of efficacy in the design with the time from the electroporation.

Herein, we report on the motivation for, design of, and progress toward a microfluidic implementation of a digital potentiometer for various physical and life science applications.

A valveless shear-driven micro-fluidic pump design (SDMFP) for hemodynamic applications is presented in this work. One of the possible medical and biomedical applications is in-vivo hemodynamic (human blood circulation) support/assist. One or more SDMFPs can be inserted/implanted into vascular lumens in a form of a stent/duct in series and/or in parallel (bypass duct) to support blood circulation in-vivo. A comprehensive review of various micro-pump designs up to about mid 2000’s is given in [1,2]. Many of micropump designs considered are not suitable for in-vivo or even in-vitro medical/biomedical applications. Operating principles, design, and SDMFP features are given in [3]. A particular design used in cardiovascular applications has no moving valves. SDMFP with Gourney-flap type valves to support high-pressure applications are developed for other applications. SDMFP could be fully bi-directional and can control its operation on the run using embedded microcontrollers and sensors. Estimated efficiency is high with low leakage resulting in low power consumption. Proprietary “fish-scale” surface coating ShearQ™ designs are implemented to improve unidirectional flow pumping efficiency. Bi-directional feature may be especially critical when clogging of blood vessels is detected. By automatically and temporarily switching into the reverse-mode operation and retrogressive flow, while inducing suction-head for a short time periods it is hoped that possibly blood conduits can be cleared/unclogged and the normal forward-flow operation resumed. Such may be an important feature if SDMFP is used in-vivo, such as, in coronary arteries which are prone to clogging leading to cardiac-arrest.

We introduce a lensless high-throughput fluorescent detection modality that can simultaneously image micro-objects and labeled cells over an ultra-wide field-of-view (FOV) of ∼8cm 2 without the use of any lenses, thin-film filters and mechanical scanners. This lensfree platform utilizes total-internal-reflection (TIR) to block the excitation light, and an inexpensive absorption filter to remove the weakly scattered light that does not obey TIR. The emitted fluorescent light from the objects is then detected on the same chip without the use of any lenses. A digital deconvolution algorithm is used to resolve overlapping fluorescent spots, enabling a resolution of ∼40–50 μm over the entire field-of-view. Such an ultra wide field-of-view lensfree fluorescent imaging modality might be very valuable for high-throughput screening applications as well as quantification of rare cells such as circulating tumor cells using ultra-large microfluidic devices.

Due to the nature of the interfaces used by microfluidic devices — syringes, syringe pumps, and tubing, delivering cells into microfluidic devices faces some practical challenges. Specifically, the unwanted settling and adhesion of cells onto various surfaces can significantly impact the effective transport of cells into the device.[1] One particular challenge is the cell settling that occurs inside devices and especially at the inlet connection port. As most tubing connections are vertical, the cell suspension moves downwards into the device before making a 90° turn into the fluidic channels. This orientation causes cells to settle, clump and adhere to surfaces around the inlet port and eventually causes clogging that prevent more cells from entering the microfluidic channels.

Microassays can take on the order of 1 to 72 hours due to complete the lack of mixing [1]. Various micromixers have been developed to quicken assay times, but they require bulky external equipment, difficult to fabrication and implementation, or are expensive. Robin Liu et al developed a low cost micromixer based on cavitation microstreaming which is easy to implement and has low power consumption. The device consists of small cavities or vertical cavity acoustic transducers (VCAT) located above a microfluidic chamber such that these small cavities trap air when a solution is injected into the chamber. A piezoelectric transducer (PZT) is then placed above the air cavities and is used to vibrate the air-liquid membrane to produce cavitation microstreaming within the chamber to cause mixing [2].

Quantitative measurements of cell osmotic behavior and membrane transport properties is critical for the development of cell-type-specific, optimal cryopreservation conditions. A microfluidic perfusion system has been developed here to measure the kinetic changes of cell volume under various extracellular conditions, in order to determine cell osmotic behavior and membrane transport properties. The system is fabricated using soft lithographic techniques and is composed of inlets, outlets, micchannels and a perfusion chamber for trapping cells. In this study Dendritic cells (DCs) are using as a model to validate our microfluidic system with a commercialized Beckham Coulter Counter (Multisizer 3). DCs are antigen presenting cells that have been increasingly used in immunotherapy for the treatment of various diseases. Cryopreservation and banking of DCs is critical to facilitate flexible and effective immunotherapy treatment. Using mouse DCs (MDC), membrane transport properties were first investigated using our microfluidic perfusion system. Cells in the microfluidic system were perfused with 3x phosphate buffer solution. The kinetics of cell volume changes under the specific extracellular conditions were monitored by a digital camera and analyzed using a biophysical model to determine water and cryoprotectant transport properties of the cell membrane. DCs were later tested using Beckman Coulter Counter, where the kinetic osmotic behaviors of cells were quantified through the correlation between electric pulses and their corresponding cell sizes. It was shown from this study that the cryobiological characteristics of DCs determined using microfluidic perfusion system and Coulter Counter agreed well.

The manipulation of particles in fluids using microfluidic devices is a fundamental task in Lab-on-a-Chip applications. Grooved structures have been widely studied in particle handling and fluid mixing in microfluidic channel systems. In this study, we report use of patterning flows produced by a series of grooved surfaces with different geometrical setups integrated into a microfluidic device, to continuously manipulate the flowing particles, ranging from 6 to 20 μm in diameters, of comparable sizes to the depth of the channel. COMSOL, a multiphysics modeling software that can help predict engineering trends, is used to systematically quantify the following parameters: 1) channel depth, 2) groove width, 3) groove depth, 4) groove angle, and 5) flow speed, which may affect the performance of separation for flowing particles inside the channel. The device is fabricated using softlithographic techniques and is composed of inlets, microfluidic channels, and outlets for loading, manipulating and retrieving cell suspensions, respectively. Experimental results indicated that the particles were evenly distributed in the entrance of the microchannel and illustrate patterns of enriching, focusing, or size-selective profiles after passing through the grooved area. The preliminary simulation results also demonstrated that particles tend to bias towards the sidewall after flowing through the grooves.

Tactile sensors are the interfaces to detect the physical properties of objects and have extensive applications in robotic sensing, biomechanics, minimally invasive surgery and human prosthetics [1]. For human prosthetics applications, the current prosthetic hand can offer only the manipulation function. With the sensing being part of the prosthetic hand, the user can get feedback from the prosthetic. This feeling can help users decrease their dependency on visual information and have better body control on weight balancing and signal limb stance.

Anthrax is an acute and deadly disease caused by the bacterium Bacillus anthracis . Upon exposure, usually through inhalation, ingestion, or cutaneous contact, B. anthracis spores begin multiplying, creating a life-threatening situation. If not quickly detected and treated, humans can die within several days. With renewed bio-terrorism concerns, there is a need for a rapid and automated system capable of sample (respiratory or blood) to answer (positive infection) so that quarantine procedures and treatment can be administered immediately. Microfluidic platforms hold great promise of fulfilling these requirements.

The ability to control mixing of reagents in MEMS systems is crucial for many biological and chemical analysis applications. However mixing in these microfluidic devices is a challenge because the flows are laminar corresponding to very low Reynolds number. In this paper mixing of such reagents in simple microchannel geometries is investigated computationally. A novel concept of “split flow design” is applied to these simple microchannel configurations. Significant improvement in mixing is seen by employing the split flow design technique.

An optical fiber biosensor has been presented for monitoring drug delivery inside the body in real time. Over the decades several optical techniques have been realized to monitor drug delivery, however, those are not that much efficient as the one presented here. In this paper, a new micromachined optical fiber biosensor has been demonstrated with both theoretical and numerical models. The detailed fabrication processes have been outlined in a multimode optical fiber which is based on MEMS fabrication. The sensor is designed by following the basic principle of Fabry-Perot interferometer. The optical biosensor presented here could be able to detect and monitor the drug delivery in real time and it could also potentially be used in the area of microfluidics, nano research and other biomedical applications.

The performance of prosthetic hands and robotic manipulators is severely limited by their having little or no tactile information compared to the human hand. Technologies such as MEMS, microfluidics, and nanoparticles have been used to produce arrays of force sensors, but these are generally not robust enough to mount on curved, deformable finger pads or to use in environments that include dust, fluids, sharp edges and wide temperature swings. Furthermore, it is not clear how the prosthetic controller will use the tactile information, so it is difficult to generate specifications for these sensors.

Microfluidic droplet systems have shown great promise and numerous advantages in the recent development of high throughput chemical and biochemical assays. With precise metering and manipulation of reagents at small scale, various applications such as protein crystallization [1], nanoparticle synthesis [2], physiological fluids diagnostics [3] and etc. have employed such systems and achieved success.

In microfluidic related chemical and biological applications, mixing on the micro scale is important and has been considered as one of the most challenging tasks. With a trend for polymeric microfluidic systems, a simple yet efficient passive micromixer is highly preferred [1–4]. We developed a novel passive micromixer with 3D porous microstructure on a polymer chip. The fabrication process uses high-intensity focused ultrasound to selectively foam gas-impregnated polymers. The selective ultrasonic foaming technique is simple, low-cost, and biocompatible. The porous microstructure is easily controlled by adjusting the parameters of the ultrasonic foaming process. The 3D porous microstructure can split, stretch, fold and break the mixing flows in microfluidic channels and thus dramatically improve the mixing efficiency.

The aim of this project is to develop a cost effective point of care (POC) microfluidic diagnostic device to detect the presence of active tuberculosis (TB) in Human Immunodeficiency Virus (HIV) co-infected individuals in developing countries. According to the World Health Organization (WHO), 8.8 million people develop new cases of active TB each year in addition to the many millions of untreated existing cases. Current TB diagnostic tests are less accurate in detecting active TB in HIV co-infected individuals. Hence, the development of a fast, affordable, portable and handheld device to accurately detect active TB is necessary. As there are different stages of TB infection, it is important to detect the presence and progress of the infection. Our device design utilizes a serological assay in a microfluidic device, incorporating protein antigen microarrays spotted onto nitrocellulose, to detect TB at various stages of the disease. Features of the design include a microfilter to separate serum from the blood sample to be used, a passive pump to ensure uniform continuous flow, and an immunosensor to detect and analyze results.

Lab-on-a-Chip technology now becomes increasingly attractive due to advantages such as reduced sample size, reduced reagent consumption, shortened analysis time, potential for high throughput and automation and reduced costs, leading to the potential for manufacturing of disposable devices. On such microchip system, the ability to handling microfluid is important. Extensive microfluidic handling componets including microflow regulator, microfluidic sensor, microvalve and micropump have been reported. Although these microfluid handling methods are successful, for the polymer based microfluidic device, a simple design, easy fabrication and the ability to integrate into the microsystem lacks report. In this paper, we presented such microvalve by utilizing the hydrophobicity of the PDMS material, a popular biocompatible material widely used in microfluidic system. The valve utilized air trapped on the side wall of microchannel by a special microconcave structure design. Controlled by an external coil heater, the trapped air will be enlarged to reduce channel width and so reduce the fluid flow in the microchannel. The valve can work in on/off mode or on flow regulating mode depending on specific flow control requirement.

Accounting for more than 13 million deaths a year, infectious diseases have become the world’s biggest killer of children and young adults worldwide [1]. Diagnostic tools and technologies are vital towards identifying the presence and treatment of these diseases. Detection methods have commonly relied on DNA using polymerase-chain-reaction (PCR), however antibody methods have become popular due to growing trends in technology and detection sensitivity. ImmPORT Therapeutics, a leading group in generating infectious disease proteome microarrays, has developed multiplex systems for comprehensive analysis of immune responses to multiple infectious diseases [2]. Current microarray handling however requires conventional lab-bench methods that require whole-day processes and large amounts of user-handling confined to laboratory settings. Miniaturization of laboratory processes would provide numerous advantages in terms of cost, time, portability and multistage automation in addition to what is already offered. The proposed microfluidic device is a colorimetric enzyme-linked-immunosorbant assay (ELISA) for antibody detection of infectious agents that draws on ImmPORT Therapeutics technology with a purpose of decreasing reagent volumes and times potentially unattainable through conventional methods.

Using non-lithographic fabrication methods developed in our laboratory, we prepared continuous-flow microfluidic analyzers. We tested these devices in experiments involving detection of bacterial endospores. The detection was based on the enhancement of the fluorescence of a cationic dye, 3,3′-diethylthiacyanine iodide (THIA), in the presence of spores. We were able to detect as few as ~10 5 spores when injected in a device. The measurements with the micro-fluidic devices manifested significantly higher sensitivity for bacterial spores than for vegetative bacteria. Such distinction between spores and vegetative bacteria could not be achieved with THIA using steady-state emission measurements.