Four-part differential leukocyte count using μflow cytometer

This paper reports the four-part differential leukocyte count (DLC) of human blood using a MEMS microflow (μflow) cytometer. It is achieved with a two-color laser-induced fluorescence (LIF) detection scheme. Four types of leukocytes including neutrophils, eosinophils, lymphocytes and monocytes are identified in blood samples, which are stained by fluorescein isothiocyanate (FITC) and propidium iodide (PI). The DLC results show good correlation with the count from a commercial hematology analyzer. The whole system is also implemented into a portable instrument for space application

Design and fabrication of a micro Coulter counter with thin film electrodes

We report a new approach for micro Coulter counter with thin film electrodes. Traditional Coulter counter measures DC resistance change to sense particles passing through an aperture between two flow chambers. One of the, biggest challenges to miniaturize the device is to overcome the large resistance encountered. We propose a new approach to use thin film metal electrodes in micron size range for sensing. Resolution can be improved and it's easy for system integration. A device based on this approach was built and tested

Hybrid dispersion laser scanner.

Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points

On-Orbit, Immuno-Based, Label-Free White Blood Cell Counting System with Microelectromechanical Sensor Technology (OILWBCS-MEMS)

Aurora Flight Sciences, in partnership with Draper Laboratory, has developed a miniaturized system to count white blood cells in microgravity environments. The system uses MEMS technology to simultaneously count total white blood cells, the five white blood cell differential subgroups, and various lymphocyte subtypes. The OILWBCS-MEMS detection technology works by immobilizing an array of white blood cell-specific antibodies on small, gold-coated membranes. When blood flows across the membranes, specific cells' surface protein antigens bind to their corresponding antibodies. This binding can be measured and correlated to cell counts. In Phase I, the partners demonstrated surface chemistry sensitivity and specificity for total white blood cells and two lymphocyte subtypes. In Phase II, a functional prototype demonstrated end-to-end operation. This rugged, miniaturized device requires minimal blood sample preparation and will be useful for both space flight and terrestrial applications

An Optofluidic Lens Biochip and an x-ray Readable Blood Pressure Microsensor: Versatile Tools for in vitro and in vivo Diagnostics.

Three different microfabricated devices were presented for use in vivo and in vitro diagnostic biomedical applications: an optofluidic-lens biochip, a hand held digital imaging system and an x-ray readable blood pressure sensor for monitoring restenosis. An optofluidic biochip–termed the ‘Microfluidic-based Oil-Immersion Lens’ (mOIL) biochip were designed, fabricated and test for high-resolution imaging of various biological samples. The biochip consists of an array of high refractive index (n = 1.77) sapphire ball lenses sitting on top of an oil-filled microfluidic network of microchambers. The combination of the high optical quality lenses with the immersion oil results in a numerical aperture (NA) of 1.2 which is comparable to the high NA of oil immersion microscope objectives. The biochip can be used as an add-on-module to a stereoscope to improve the resolution from 10 microns down to 0.7 microns. It also has a scalable field of view (FOV) as the total FOV increases linearly with the number of lenses in the biochip (each lens has ~200 microns FOV). By combining the mOIL biochip with a CMOS sensor, a LED light source in 3D printed housing, a compact (40 grams, 4cmx4cmx4cm) high resolution (~0.4 microns) hand held imaging system was developed. The applicability of this system was demonstrated by counting red and white blood cells and imaging fluorescently labelled cells. In blood smear samples, blood cells, sickle cells, and malaria-infected cells were easily identified. To monitor restenosis, an x-ray readable implantable blood pressure sensor was developed. The sensor is based on the use of an x-ray absorbing liquid contained in a microchamber. The microchamber has a flexible membrane that is exposed to blood pressure. When the membrane deflects, the liquid moves into the microfluidic-gauge. The length of the microfluidic-gauge can be measured and consequently the applied pressure exerted on the diaphragm can be calculated. The prototype sensor has dimensions of 1x0.6x10mm and adequate resolution (19mmHg) to detect restenosis in coronary artery stents from a standard chest x-ray. Further improvements of our prototype will open up the possibility of measuring pressure drop in a coronary artery stent in a non-invasively manner.PhDMacromolecular Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111384/1/toning_1.pd

Mems (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms for Magnetic Cell Separation

Microfluidic platforms for magnetic cell separation were developed and investigated for isolation of magnetic particles and magnetically tagged cells from a fluidic sample. Two types of magnetic separation platforms were considered: an Isodynamic Open Gradient Magnetic Sorter (OGMS) and a multistage bio-ferrograph. Miniaturized magnets were designed using magnetostatic simulation software, microfluidic channels were fabricated using microfabrication technology and magnetic separation was investigated using video microscopy and digital image processing. The isodynamic OGMS consisted of an external magnetic circuit and a microfabricated channel (biochip) with embedded magnetic elements. The biochip is placed inside the magnetic field of the external circuit to obtain nearly constant energy density gradient in the portion of the channel used for separation. The microfabrication process involved improving adhesion of thick SU-8 to Pyrex, forming enclosed channels using a low temperature SU-8 adhesive bonding, and fabricating patterned plating molds on both sides of the bonded wafers. Adhesion of SU-8 to Pyrex was improved by using a highly crosslinked thin SU-8 adhesion layer, and enclosed microchannels were fabricated using selectively exposed SU-8 bond formation layers. Electroplating molds were fabricated using KMPR photoresists and were integrated on both sides of the bonded wafers. The multistage bio-ferrograph consisted of a microfabricated enclosed channel placed on the surface of a multi-unit magnet (4 trapezoidal magnets placed in series) assembly such that magnetic cells from a flowing stream would be deposited on designated locations. The OGMS was able to deflect magnetic particles by 500-1000 microns and the capture efficiencies of magnetic particles and cells with the multistage bio-ferrograph were 80-85 percent and 99.5 percent, respectivel

Mems (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms for Magnetic Cell Separation

Microfluidic platforms for magnetic cell separation were developed and investigated for isolation of magnetic particles and magnetically tagged cells from a fluidic sample. Two types of magnetic separation platforms were considered: an Isodynamic Open Gradient Magnetic Sorter (OGMS) and a multistage bio-ferrograph. Miniaturized magnets were designed using magnetostatic simulation software, microfluidic channels were fabricated using microfabrication technology and magnetic separation was investigated using video microscopy and digital image processing. The isodynamic OGMS consisted of an external magnetic circuit and a microfabricated channel (biochip) with embedded magnetic elements. The biochip is placed inside the magnetic field of the external circuit to obtain nearly constant energy density gradient in the portion of the channel used for separation. The microfabrication process involved improving adhesion of thick SU-8 to Pyrex, forming enclosed channels using a low temperature SU-8 adhesive bonding, and fabricating patterned plating molds on both sides of the bonded wafers. Adhesion of SU-8 to Pyrex was improved by using a highly crosslinked thin SU-8 adhesion layer, and enclosed microchannels were fabricated using selectively exposed SU-8 bond formation layers. Electroplating molds were fabricated using KMPR photoresists and were integrated on both sides of the bonded wafers. The multistage bio-ferrograph consisted of a microfabricated enclosed channel placed on the surface of a multi-unit magnet (4 trapezoidal magnets placed in series) assembly such that magnetic cells from a flowing stream would be deposited on designated locations. The OGMS was able to deflect magnetic particles by 500-1000 microns and the capture efficiencies of magnetic particles and cells with the multistage bio-ferrograph were 80-85 percent and 99.5 percent, respectivel

Towards Bio-impedance Based Labs: A Review

In this article, some of the main contributions to BI (Bio-Impedance) parameter-based systems for medical, biological and industrial fields, oriented to develop micro laboratory systems are summarized. These small systems are enabled by the development of new measurement techniques and systems (labs), based on the impedance as biomarker. The electrical properties of the life mater allow the straightforward, low cost and usually non-invasive measurement methods to define its status or value, with the possibility to know its time evolution. This work proposes a review of bio-impedance based methods being employed to develop new LoC (Lab-on-a-Chips) systems, and some open problems identified as main research challenges, such as, the accuracy limits of measurements techniques, the role of the microelectrode-biological impedance modeling in measurements and system portability specifications demanded for many applications.Spanish founded Project: TEC 2013-46242-C3-1-P: Integrated Microsystem for Cell Culture AssaysFEDE

Cell Culture on MEMS Platforms: A Review

Microfabricated systems provide an excellent platform for the culture of cells, and are an extremely useful tool for the investigation of cellular responses to various stimuli. Advantages offered over traditional methods include cost-effectiveness, controllability, low volume, high resolution, and sensitivity. Both biocompatible and bioincompatible materials have been developed for use in these applications. Biocompatible materials such as PMMA or PLGA can be used directly for cell culture. However, for bioincompatible materials such as silicon or PDMS, additional steps need to be taken to render these materials more suitable for cell adhesion and maintenance. This review describes multiple surface modification strategies to improve the biocompatibility of MEMS materials. Basic concepts of cell-biomaterial interactions, such as protein adsorption and cell adhesion are covered. Finally, the applications of these MEMS materials in Tissue Engineering are presented.Institute of Bioengineering and Nanotechnology (Singapore)Singapore. Biomedical Research CouncilSingapore. Agency for Science, Technology and ResearchSingapore. Agency for Science, Technology and Research (R-185-001-045-305)Singapore. Ministry of EducationSingapore. Ministry of Education (Grant R-185- 000-135-112)Singapore. National Medical Research CouncilSingapore. National Medical Research Council (Grant R-185-000-099-213)Jassen Cilag (Firm)Singapore-MIT Alliance (Computational and Systems Biology Flagship Project)Global Enterprise for Micro-Mechanics and Molecular Medicin