Methods and systems for identifying a particle using dielectrophoresis

A system for identifying a particle. The system includes a microfluidic device; a microelectrode array including a plurality of electrodes, the microelectrode array disposed within the microfluidic device; a plurality of particles suspended in a solution and delivered to the microelectrode array using the microfluidic device; a signal generator operatively coupled to the microelectrode array; a particle detector adjacent to the microelectrode array; and a controller in operative communication with the signal generator and the particle detector. The controller is configured to apply an oscillating voltage signal to the microelectrode array between a low frequency and a high frequency at a sweep rate, wherein the sweep rate is no more than a maximum sweep rate, and determine a distribution of the plurality of particles relative to the microelectrode array at a plurality of frequency levels between the low frequency and the high frequency.https://digitalcommons.mtu.edu/patents/1139/thumbnail.jp

Data representing two separate LC-MS methods for detection and quantification of water-soluble and fat-soluble vitamins in tears and blood serum

Tears serve as a viable diagnostic fluid with advantages including less invasive sample to collect and less complex to prepare for analysis. Several water-soluble and fat-soluble vitamins were detected and quantified in human tears and compared with blood serum levels. Samples from 15 family pairs, each pair consisting of a four-month-old infant and one parent were analyzed; vitamin concentrations were compared between tears and blood serum for individual subjects, between infants and parents, and against self-reported dietary intakes. Water-soluble vitamins B1, B2, B3 (nicotinamide), B5, B9 and fat-soluble vitamin E (α-tocopherol) were routinely detected in tears and blood serum while fat-soluble vitamin A (retinol) was detected only in blood serum. Water-soluble vitamin concentrations measured in tears and blood serum of single subjects were comparable, while higher concentrations were measured in infants compared to their parents. Fat-soluble vitamin E concentrations were lower in tears than blood serum with no significant difference between infants and parents. Serum vitamin A concentrations were higher in parents than infants. Population trends were compiled and quantified using a cross correlation factor. Strong positive correlations were found between tear and blood serum concentrations of vitamin E from infants and parents and vitamin B3 concentrations from parents, while slight positive correlations were detected for infants B3 and parents B1 and B2 concentrations. Correlations between infants and parents were found for the concentrations of B1, B2, B3, and E in tears, and the concentrations of B2, A, and E in blood serum. Stronger vitamin concentration correlations were found between infants and parents for the breast-fed infants, while no significant difference was observed between breast-fed and bottle-fed infants. This work is the first to demonstrate simultaneous vitamin A, B, and E detection and to quantify correlations between vitamin concentrations in tears and blood serum. Our results suggest that tears are a viable biofluid to monitor nutritional health because they sufficiently mirror blood serum data and may enhance the speed of deficiency diagnoses

ASEE safe zone workshops and virtual community of practice to promote LGBTQ equality in engineering

Even though recent years have seen significant advances in LGBTQ (lesbian, gay, bisexual, transgender, and queer) equality in the U.S. through legislation and social acceptance, research shows that LGBTQ students and faculty on college campuses still experience exclusion and dis-crimination. This paper describes a transformative project that links diversity research with a faculty development initiative to promote LGBTQ equality in engineering. . The aims of the project are to (1) identify aspects of engineering culture that present barriers to LGBTQ equality, (2) build knowledge and skills to disrupt discrimination and promote LGBTQ equality in engineer-ing departments on college campuses and (3) to identify best practices for promoting LGBTQ equality in engineering

Interactive Panel on Perspectives and Practical Skills for Men as Advocates for Gender Equity

Men can serve unique and critical roles as advocates of gender equity, particularly in maledominated units or organizations, such as most engineering departments and many universities. This panel brings together a group of men with diverse backgrounds and experiences to discuss their perspectives and offer practical skills for men to effectively serve as advocates for gender equity. This paper augments the panel and captures the backgrounds, experiences, perspectives, and recommendations of the panelists, thereby providing a lasting resource for those unable to attend the panel or future interested individuals. The information we present targets men and administrators, who will better understand the barriers to advocacy, learn best-practices of effective advocacy, and hear first-hand experiences of successful advocacy

Semester-long Concept Development Projects in Chemical Engineering Electives Course

Elective courses in the chemical engineering curriculum can serve many purposes that include exposure to a specialized topic, survey of diverse topics, and/or enhancing the problem solving skills. This paper will describe the use of a semester long project which serves the purpose of increasing depth of knowledge in a specialized topic, contextualization within a broader field, as well as a new skill-set. The specialized topic is an Analytical Microdevice Technology elective course, which is structured to reinforce concepts from transport, unit operations, and plant (i.e. microdevice) courses – at the microscale. The topic is contextualized within the broader field by using example devices pulled by the students from the scientific literature, then outlining connections to traditional chemical engineering concepts and applicability in consumer/other markets. The new skills include problem solving skills, information filtering skills, and logic skills as well as practice linking unique concepts together. Regular discussions and guidance are provided to the students via biweekly reports that are structured to build sequentially from general project concept to substantial depth in each supporting technology utilized in the project. Simulations or experiments are completed by the students on the final concept, as appropriate. The concept development projects are a concerted effort to strategically develop these skills in Chemical Engineering students. Students work in mixed graduate and undergraduate student teams to develop a novel concept via independent reading, discussion, and mini-lectures. A majority of the content in the course is student-driven and is developed dynamically based on the technologies that the student pull into their projects. This work is based on the premise that engagement of students in critical thinking and independent information gathering exercises increases student awareness of and excitement for chemical engineering and the likelihood of engaging in life-long learning in an industrial or academic setting. This paper will provide descriptions of how the project process is managed and guided as well as assessments of student learning and attitudes

Reaction-free concentration gradient generation in spatially non-uniform AC electric fields

The ability to generate stable, spatiotemporally controllable concentration gradients is critical for both electrokinetic and biological applications such as directional wetting and chemotaxis. Electrochemical techniques for generating solution and surface gradients display benefits such as simplicity, controllability, and compatibility with automation. Here, we present an exploratory study for generating micro-scale spatiotemporally controllable gradients using a reaction-free electrokinetic technique in a microfluidic environment. Methanol solutions with ionic Fluorescein isothiocyanate (FITC) molecules were used as an illustrative electrolyte. Spatially non-uniform alternating current (AC) electric fields were applied using hafnium dioxide (HfO2) coated Ti/Au electrode pairs. Results from spatial and temporal analysis, along with control experiments suggest that the FITC ion concentration gradient in bulk fluid (over 50 µm from the electrode) was established due to spatial variation of electric field density, and was independent of electrochemical reactions at the electrode surface. The established ion concentration gradients depended on both amplitudes and the frequencies of the oscillating AC electric field. Overall, this work reports a novel approach for generating stable and spatiotemporally tunable gradients in a microfluidic chamber using a reaction-free electrochemical methodology

Reaction-Free Concentration Gradient Generation in Spatially Nonuniform AC Electric Fields

The ability to generate stable, spatiotemporally controllable concentration gradients is critical for both electrokinetic and biological applications such as directional wetting and chemotaxis. Electrochemical techniques for generating solution and surface gradients display benefits such as simplicity, controllability, and compatibility with automation. Here, we present an exploratory study for generating microscale spatiotemporally controllable gradients using a reaction-free electrokinetic technique in a microfluidic environment. Methanol solutions with ionic fluorescein isothiocyanate (FITC) molecules were used as an illustrative electrolyte. Spatially nonuniform alternating current (AC) electric fields were applied using hafnium dioxide (HfO2)-coated Ti/Au electrode pairs. Results from spatial and temporal analyses along with control experiments suggest that the FITC ion concentration gradient in bulk fluid (over 50 μm from the electrode) was established due to spatial variation of electric field density, and was independent of electrochemical reactions at the electrode surface. The established ion concentration gradients depended on both amplitudes and frequencies of the oscillating AC electric field. Overall, this work reports a novel approach for generating stable and spatiotemporally tunable gradients in a microfluidic chamber using a reaction-free electrochemical methodology

Explorations of ABO-Rh antigen expressions on erythrocyte dielectrophoresis: Changes in cross-over frequency

A quadrupole dielectrophoretic microdevice was utilized to examine the ABO-Rh dependencies on erythrocyte polarizations. This important step toward medical microdevice technology would transform key clinical blood tests from the laboratory into the field. Previous work in dielectrophoretic microdevices demonstrated that the large number of ABO antigens on erythrocyte membranes impacts their dielectrophoretic signature at 1MHz. This work explores the dielectrophoretic behavior of native human erythrocytes categorized by their ABO-Rh blood types and directly compares these responses to the same erythrocyte sample modified to remove the A and B antigens. A β(1-3)-galactosidase enzyme was utilized to cleave the ABO polysaccharide backbone at the galactosidase bonds. The enzymatic reaction was optimized by comparing agglutination of the native and modified blood cells in addition to UV-Vis and HPLC analysis of the reaction effluent for saccharide residues. Next, the dielectrophoretic behaviors of the native and modified erythrocytes were visually verified in a quadrupole electrode microdevice over a frequency range from 100kHz to 80MHz. The lower cross-over frequency (COF), which transitions from negative to positive dielectrophoresis, for ABO blood types tested (A+, A-, B+, B-, AB+, O+ and O-) differed over the range from 17 to 47MHz. The COFs of the corresponding enzyme-modified erythrocytes were also determined and the range narrowed to 29-41MHz. A second COF in the 70-80MHz range was observed and was reduced in the presence of the transmembrane Rhesus factor. These results suggest that antigen expression on erythrocyte membrane surfaces influence cell polarizations in nonuniform AC fields

Electrochemical detection techniques in micro- and nanofluidic devices

© 2014, Springer-Verlag Berlin Heidelberg. Electrochemical techniques are widely used in microfluidic and nanofluidic devices because they are suitable for miniaturization, have better sensitivity compared to optical detection techniques, and their components can be reliably microfabricated. In addition to the detection and quantification of analytes, electrochemical techniques can be used to monitor processes such as biological cell death and protein/DNA separations/purifications. Such techniques are combined with micro- and nanofluidic devices with point-of-care (POC) applications in mind, where cost, footprint, ease of use, and independence from peripheral equipment are critical for a viable design. A large variety of electrode materials and device configurations have been employed to meet these requirements. This review introduces the reader to the major electrochemical techniques, materials, and fabrication methods for working and reference electrodes, and to surface modifications of electrodes to facilitate electrochemical measurements, in the context of micro- and nanofluidic devices. The continuing development of these techniques holds promise for the next-generation lab-on-a-chip devices, which can realize the goals of this technology such as POC clinical analysis