A portable centrifuge was developed for point-of-care measurement of hematocrit in low-resource settings. The centrifuge consists of an electromechanical motor with performance optimized and controlled for centrifugal separation of blood in capillary tubes. The motor is powered by a set of rechargeable batteries and spins the samples at a controlled rate between 1000 and 15,000 revolutions per minute (RPM). Preliminary test results show that an accurate hematocrit reading can be made after operating the centrifuge for 110 seconds at 10,000 RPM. The centrifuge can be operated for almost three 8-hour work days at a 25% duty cycle when the batteries are fully charged, and it can measure hematocrits over the entire clinically relevant range with minimal experimental error. With a total system cost of less than $30, the portable centrifuge developed in this work has the potential to make a large impact on centrifugal separation applications such as the screening process for anemia in any clinical setting.

A curved design for in-plane microand nano-electromechanical switches based on a single clamped cantilever is proposed, optimized with finiteelement simulations and demonstrated experimentally. The design enables precise control of the switch motion and of the closed-state air gap, resulting in a uniform electrostatic field and increased robustness. The switch size and curvature are optimized for actuation voltage, actuation energy and the electrostatic field strength. These optimizations and the proposed fabrication process are amenable to microand nano-electromechanical switches. The scalability of the concept is demonstrated with simulations of nanoscale relays in terms of force and energy, showing that the concept is suitable for sub-100 aJ switching energy. Experimental results on microscale devices demonstrate the advantages of the curved MEM switches, namely a fabrication process with a single sacrificial layer for a switch with a low actuation voltage and excellent robustness. The designed as well as the experimentally observed breakdown voltage is four times higher than the contact voltage, thus enabling a large operating window for electromechanical switches. 2013 J. Micromech. Microeng. 23 025024 Journal of Micromechanics and Microengineering Highlights of 2013 Editor-in-Chief: W Fang, National Tsing Hua University, Taiwan

A low-cost nano-gap interdigitated electrode array (IDA) on a polymer substrate has been developed to realize a disposable nano-biosensor for biochemical clinical analysis. Utilizing the common instruments for optical lithography, nano-scale features were fabricated on a thermoplastic polymer to produce an electrochemical nano-biosensor in a disposable format. The IDA was realized on a 3-inch cyclo-olefin copolymer wafer, which illustrates the utility of our fabrication technique as a large-area nanofabrication process for a polymer using low temperature processes. In order to demonstrate the use of the sensor for lab-on-a-chip applications, the developed IDA was integrated with a microfluidic channel and applied for the electrochemical detection of poly-aminophenol with 10(-8) M detection limit. The results indicate the developed fabrication technique is suitable for the inexpensive mass fabrication of highly sensitive nano-biosensors for disposable applications.

Background Point-of-care glucose meters are an important tool in assessing blood glucose levels and managing insulin dosage of diabetic patients. Glucose meters have been designed to operate in temperature-controlled environments, such as hospitals, and can be unsuitable for use in extreme conditions found in an ambulatory setting. A thermo-modulating container was developed to prevent glucose meter low-temperature errors. Methods The device was designed to maintain the operating temperature of a professional model glucose meter within the range specified by the manufacturer (15°C–40°C). The container consisted of a hard outer shell with insulation, thermostat, and heating elements. The glucose meter was placed inside the container and subjected to environmental temperatures ranging from −15°C to 15°C. Results When used in passive configuration at an environmental temperature of 10°C, the container extended the operating time of the glucose meter from 1 hour to 7 hours before receiving a temperature error. When used in the active configuration at the same temperature, the container extended the operating time to 24 hours. This sequence of tests was repeated at an extreme temperature condition (−15°C), with the container extending device operation from under 10 minutes to 38 and 251 minutes using passive and active modes, respectively. Conclusions The device provides significant protection against glucose meter low-temperature errors. As a result, the container may be applied for transportation and storage of glucose meters in a cold weather ambulatory setting.

In this work, a new method of rapidly fabricating thermopolymer and elastomer microfluidic channels has been developed and characterized for production of microfluidics with fixed aspect ratio and 3D tapered channels. A unique way to attain a desired channel depth by simply altering channel width is demonstrated. This rapid prototyping method is compatible with replication methods such as injection molding, hot embossing and elastomer casting and offers the ability to fabricate multiple channel depths (5 microm-1 mm) simultaneously in a single lithographic step. This method yields facile fabrication of 3-dimensionally tapered channels and polymer lab chips.

A new method for the self-assembly of a carbon nanotube (CNT) using magnetic capturing and fluidic alignment has been developed and characterized in this work. In this new method, the residual iron (Fe) catalyst positioned at one end of the CNT was utilized as a self-assembly driver to attract and position the CNT, while the assembled CNT was aligned by the shear force induced from the fluid flow through the assembly channel. The self-assembly procedures were successfully developed and the electrical properties of the assembled multi-walled carbon nanotube (MWNT) and single-walled carbon nanotube (SWNT) were fully characterized. The new assembly method developed in this work shows its feasibility for the precise self-assembly of parallel CNTs for electronic devices and nanobiosensors.

A mass-producible method for fabricating nanoparticle assemblies using nanoinjection-molded polymer templates with deposition and selective removal has been developed and characterized in this work. Results are demonstrated for assembly of multiple nanoparticle sizes and types in 1-D and 2-D formats over large areas. Template dimensions such as width and depth are used to control the assembled structures, including the quantity and type of nanoparticles in the assembly. This method offers a high-throughput, low-cost approach to nanoscale assembly for applications in optical, electronic, and biomedical devices.

In this work, a new method of fabricating microfluidic channels with fixed aspect ratio is described and characterized. This provides a unique way to attain a desired channel depth by simply altering channel width. This approach offers the ability to fabricate an infinite range of channel depths simultaneously in a single lithographic step and fabrication of channel geometries previously unachievable.

Precise self-assembly of carbon nanotubes (CNTs) by magnetic attraction on a catalyst and alignment by fluidic shear forces is reported in this work. The solution containing dispersed nanotubes was flowed in a microchannel and external magnetic field was applied by a permanent magnet for attracting a metal catalyst located at the end of the CNT. The assembly procedure and electrical characterization of the assembled nanotubes are presented and results are discussed. This work can provide a potential breakthrough for creating massively parallel CNT circuits for high performance nano electronic devices or nano biosensors.

This paper presents a fully integrated nano interdigitated electrodes array (nIDA) and microfluidic system on polymer substrate. It can be used as a miniaturized, sensitive, and easy-to-use impedimetric sensor for genomics, proteomics, and cellular analysis. The benefits gained from a nanoscale IDA is very high sensitivity for monitoring protein binding behavior. With the intention of integrating this nano biosensor into a lab-on-a-chip device, a gold nIDA has been successfully patterned on polymer (cyclic olefin copolymer, COC) substrate, which has been widely used for disposable lab-on-a-chip applications. The fabricated device has been characterized in deionized (DI) water and different concentrations of KCl salt solution ranging from 10−1 to 10−5 M using electrochemical impedimetric spectroscopy (EIS). Experimental and theoretical impedance responses are well matched. The preliminary test shows that the impedance from the same buffer solution increases after protein binding (mouse monoclonal anti-rabbit immunoglobulin, IgG) at the gold electrode surface and the impedance change is directly related to the IgG concentration. These results support the feasibility of applying the proposed device as a sensitive protein immunosensor on a disposable polymer substrate.

In this paper, a high-throughput method for fabricating submicrometer electrodes on polymer substrates is introduced and results are presented. This new process, known as nanoinjection lithography, combines nanoinjection molding with trench-filling techniques to create submicrometer electrodes on thermoplastic polymers. The fabrication method and resulting electrodes are characterized in this work using scanning electron microscopy, surface profilometry, and atomic force microscopy. The ability to fabricate submicrometer electrodes on polymer chips in a high-throughput process may allow the mass-production of ultrasensitive biosensors for point-of-care medical devices.

A passive microfluidic mixer with high performance is designed and fabricated in this work. Diamond-shaped obstacles were chosen to split the flow into several streams, which are then guided back together after the obstacle. To keep pressure drop low, the channel cross-sectional area was maintained equal to the input cross-sectional area, and this was held constant throughout the device. The proposed design was modeled using computational fluid dynamics (CFD) software. The effects of channel width, channel length, location of obstructions, and Reynolds Number (Re) were investigated. The simulated results were verified experimentally. Simulation data showed that the designed micromixer achieved. 90% mixing at a channel length of 4.35 min with pressure drop of 584 Pa at Re = 1, while experimental data for Re = 0.1 showed 90% mixing at 7mm. The mixer functions well especially at the low Re (Re = 0. 1).

Nano interdigitated array (IDA) electrodes (electrode finger width = 100 nm; finger spacing = 200 nm; surface area = 0.2 mm2) have been fabricated and characterized amperometrically for the electrochemical detection of the concentrations of reversible redox species. Using p-aminophenol as the redox species, a detection limit of 10 pM of the species concentration has been achieved. This detection limit is three orders of magnitude lower than the micro IDA counterpart that has been reported to date, proving the enhanced redox cycling at the nano IDA electrodes. Using a higher electron dose, the proximity effect of the electron beam in the e-beam lithography process has been utilized to reduce the duration of the nano IDA pattern transfer step to less than 30 minutes. This makes it possible to fabricate the entire sensor within a day, including the electrode metal evaporation, metal lift-off and electroplating of reference electrode.

The nanotechnology module was designed to introduce nanotechnology and the ideas behind it to students who know little about the subject. Students participate In hands-on activities that give them a better sense of how small the nano world really is, and to learn about the various applications of nanotechnology at the same time.

This paper describes the recent activities of electrical and computer engineering doctoral students in the design, development, and implementation of lessons for high school mathematics and science classes. The graduate students, called fellows, worked in secondary classrooms in the Cincinnati Public Schools District as a part of Project STEP at the University of Cincinnati, which is funded by the National Science Foundation GK-12 Program. The fellows formed partnerships with secondary math and science teachers to generate new lessons, activities, and resources to enhance the STEM skills of high school students. Additionally, the Fellows used their engineering expertise to bring authentic learning experiences into the classroom and introduced concepts in their field of engineering to underserved student populations. This paper discusses observations and reflections by the fellows regarding aspects of the activities that had the most impact on student learning and interest in engineering, which was measured by self-reported student surveys

In this work, the fabrication of nanochannels with microfluidic interface using poly(dimethylsiloxane) (PDMS) casting on Ti/Si nanomold is presented. This new method combines e-beam lithography, Ti metal deposition, photolithography, and casting in PDMS. The combination of nanofabrication with PDMS casting allows the patterning of high-resolution nanostructures while also maintaining high throughput. Additionally, the microfluidic interface simplifies integration with current testing and characterization procedures. This allows the rapid fabrication of nanochannels for basic nanofluidic transport studies, integration with current microfluidic devices, and applications in drug delivery.