A multiaxial stretchable interconnect using liquid-alloy-filled elastomeric microchannels

We report on the fabrication and characterizations of a multiaxial stretchable interconnect using room-temperature liquid-alloy-filled elastomeric microchannels. Polydimethylsiloxane (PDMS) microchannels coated at the bottom with a gold wetting layer were used as the reservoirs which were subsequently filled by room-temperature liquid alloy using microfluidic injection technique. Using a diamond-shaped geometry to provide biaxial performance, a maximum stretchability of 100% was achieved (R=0.24 ). Less than 0.02 resistance variation was measured for 180 bending. Active electronics, light emitting diode, was also integrated onto the PDMS substrate with stretchable interconnects to demonstrate stable electrical connection during stretching, bending, and twisting

Introducing a Framework to Capture and Reuse Tacit Knowledge in Software Project Management

In rapidly growing global companies, comprehensive training programs as well as in depth sharing of knowledge are essential factors to maintain the quality of human capital despite rapid expansion. Different dimensions of Knowledge management address the need and approach to leverage dispersed knowledge in order to make it visible and accessible for everyone to improve organizational performance. However, there has been a scarcity of successful and holistic models that define and categorize tacit knowledge in order to capture and distribute it for the benefit of others. This paper focuses on developing a framework in order to capture experiences regarding software project management and to provide a platform for managers to inherit knowledge from and bequeath their learning to others at large organizations. In order to build up and enhance the framework, the majority of information was gleaned from intensive interviews with top software project managers at Infosys, a well-known global company in the field of software development and consulting services. The final framework we developed can act as a comprehensive data-repository for capturing, storing, searching, and distributing tacit knowledge of project managers

Extremely-Wide-Range Supply-Independent CMOS Voltage References for Telemetry-Powering Applications

This paper reports a voltage reference circuit in standard CMOS process. It exhibits excellent supply independency for a wide input voltage range, which is of great importance in telemetry-powered systems. This circuit is based on the well-known V GS -reference supply-independent current reference circuit, but it is designed to serve as a voltage reference . While the reference current generated by this circuit varies with the supply voltage, a self-compensating mechanism can be found in voltage-mode operation of the circuit that results in a supply-independent reference voltage. This supply independency is well observed in the static operation of the circuit over an extremely wide input range, as well as in its dynamic behavior for high frequency ripples on the input voltage. Based on the proposed idea, a multi-output voltage reference and a CMOS DC level shifter are also designed. The proposed voltage reference circuits have been fabricated using MOSIS 1.6 μm standard CMOS process. The basic voltage reference provides 957 μV/V static supply dependency, rejects input ripples of up to 8 MHz by 60± 3dB, and consumes only 15.8–36.9 μA when the input voltage varies in the range 2.6–12 V.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44083/1/10470_2006_Article_1644.pd

A manufacturable smart dressing with oxygen delivery and sensing capability for chronic wound management

Chronic non-healing wounds, impact over 6.5 million Americans, costs in excess of $25 billion to treat on an annual basis and its incidence is predicted to rise due to the prevalence of obesity and type-2 diabetes. One of the primary complications often associated with chronic wounds is the improper functionality of the peripheral vasculature to deliver O2-rich blood to the tissue which leads to wound hypoxia. Although hyperbaric oxygen therapy are widely used and accepted as an effective approach to bolster tissue O2 levels in hypoxic chronic wounds, most of such treatments require bulky equipment and often expose large areas of the body to unnecessarily elevated oxygen concentrations that can damage healthy tissue. In this paper, we present a smart low-cost wound dressing with integrated oxygen sensor and delivery for locally generating and delivering oxygen to selected hypoxic regions on the wound. The dressing is fabricated on a biocompatible water resistant/hydrophobic paper-based substrate with printed optical oxygen sensors and patterned catalytic oxygen generating regions that are connected to a flexible microfluidic systems. Oxygen generation occurs by flowing H2O2 through the channels and chemical decomposition at the catalyst printed regions on the paper substrate. The hydrophobic paper provides structural stability and flexibility while simultaneously offering printability, selective gaseous filtering, and physical/chemical protection. The fabrication process take advantage of scalable manufacturing technologies including laser processing, inkjet printing, and lamination

Naked Singularity Formation In f(R) Gravity

We study the gravitational collapse of a star with barotropic equation of state $p=w\rho$ in the context of $f({\mathcal R})$ theories of gravity. Utilizing the metric formalism, we rewrite the field equations as those of Brans-Dicke theory with vanishing coupling parameter. By choosing the functionality of Ricci scalar as $f({\mathcal R})=\alpha{\mathcal R}^{m}$, we show that for an appropriate initial value of the energy density, if $\alpha$ and $m$ satisfy certain conditions, the resulting singularity would be naked, violating the cosmic censorship conjecture. These conditions are the ratio of the mass function to the area radius of the collapsing ball, negativity of the effective pressure, and the time behavior of the Kretschmann scalar. Also, as long as parameter $\alpha$ obeys certain conditions, the satisfaction of the weak energy condition is guaranteed by the collapsing configuration.Comment: 15 pages, 4 figures, to appear in GR

Does accelerating universe indicates Brans-Dicke theory

The evolution of universe in Brans-Dicke (BD) theory is discussed in this paper. Considering a parameterized scenario for BD scalar field $\phi=\phi_{0}a^{\alpha}$ which plays the role of gravitational "constant" $G$, we apply the Markov Chain Monte Carlo method to investigate a global constraints on BD theory with a self-interacting potential according to the current observational data: Union2 dataset of type supernovae Ia (SNIa), high-redshift Gamma-Ray Bursts (GRBs) data, observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. It is shown that an expanded universe from deceleration to acceleration is given in this theory, and the constraint results of dimensionless matter density $\Omega_{0m}$ and parameter $\alpha$ are, $\Omega_{0m}=0.286^{+0.037+0.050}_{-0.039-0.047}$ and $\alpha=0.0046^{+0.0149+0.0171}_{-0.0171-0.0206}$ which is consistent with the result of current experiment exploration, $\mid\alpha\mid \leq 0.132124$. In addition, we use the geometrical diagnostic method, jerk parameter $j$, to distinguish the BD theory and cosmological constant model in Einstein's theory of general relativity.Comment: 16 pages, 3 figure

Photolithographic Approaches for Fabricating Highly Ordered Nanopatterned Arrays

In this work, we report that large area metal nanowire and polymer nanotube arrays were successfully patterned by photolithographic approach using anodic aluminum oxide (AAO) templates. Nanowires were produced by electrochemical deposition, and nanotubes by solution-wetting. The highly ordered patterns of nanowire and nanotube arrays were observed using scanning electron microscopy (SEM) and found to stand free on the substrate. The method is expected to play an important role in the application of microdevices in the future

A biaxial stretchable interconnect with liquid-alloy-covered joints on elastomeric substrate

This paper reports a biaxial stretchable interconnect on an elastomeric substrate. To increase the stretchability of interconnects, a 2-D diamond-shaped geometry of gold on a polydimethylsiloxane substrate was adopted in which the potentially breakable points were covered with room temperature liquid alloy. Finite element model simulations were performed to identify the most vulnerable points subjected to stress concentration and optimize the design process. Simulations also indicated an optimum gold thickness and linewidth that result in a minimum stress when the substrate is stretched. Four different geometries were designed, fabricated, and characterized. These included: 1) 2-D diamond-shaped gold lines connected at circular junctions with an intersection angle of 90; 2) 2-D diamond-shaped gold lines connected at circular junctions with intersection angles of 120 and 60; 3) 2-D diamond-shaped gold lines separated at circular junctions with an intersection angle of 90; and 4) 2-D diamond-shaped gold lines separated at circular junctions with intersection angles of 120 and 60. A maximum stretchability (L/L) of ~ 60% was achieved for the design in which the lines and circles were separated and had intersection angles of 120 and 60. A resistance variation of (R/R) ~ 30% was measured for this configuration