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A flexible organic reflectance oximeter array.
Transmission-mode pulse oximetry, the optical method for determining oxygen saturation in blood, is limited to only tissues that can be transilluminated, such as the earlobes and the fingers. The existing sensor configuration provides only single-point measurements, lacking 2D oxygenation mapping capability. Here, we demonstrate a flexible and printed sensor array composed of organic light-emitting diodes and organic photodiodes, which senses reflected light from tissue to determine the oxygen saturation. We use the reflectance oximeter array beyond the conventional sensing locations. The sensor is implemented to measure oxygen saturation on the forehead with 1.1% mean error and to create 2D oxygenation maps of adult forearms under pressure-cuff-induced ischemia. In addition, we present mathematical models to determine oxygenation in the presence and absence of a pulsatile arterial blood signal. The mechanical flexibility, 2D oxygenation mapping capability, and the ability to place the sensor in various locations make the reflectance oximeter array promising for medical sensing applications such as monitoring of real-time chronic medical conditions as well as postsurgery recovery management of tissues, organs, and wounds
Instrumentation in wind tunnels
Requirements in designing instrumentation systems and measurements of various physical quantities in wind tunnels are surveyed. Emphasis is given to sensors used for measuring pressure, temperature, and angle, and the measurements of air turbulence and boundary layers. Instrumentation in wind tunnels require accuracy, fast response, diversity and operational simplicity. Measurements of force, pressure, attitude angle, free flow, pressure distribution, and temperature are illustrated by a table, and a block diagram. The LDV (laser Doppler velocimeter) method for measuring air turbulence and flow velocity and measurement of skin friction and flow fields using laser holograms are discussed. The future potential of these techniques is studied
Printable stretchable interconnects
This article presents recent progress and a comprehensive overview of stretchable interconnects based on printable nanocomposites. Nanocomposite-based inks for printed stretchable interconnects have been categorized according to dispersed filler materials. They comprise of carbon-based fillers and metal-based fillers. Benefits in terms of excellent electrical performance and elastic properties make nanocomposites the ideal candidates for stretchable interconnect applications. Deeper analysis of nanocomposites-based stretchable interconnects includes the correlation between the size of fillers, percolation ratio, maximum electrical conductivity and mechanical elasticity. The key trends in the field have been highlighted using curve fitting methods on large data collected from the literature. Furthermore, a wide variety of applications for stretchable interconnects are presented
An equivalent-effect phenomenon in eddy current non-destructive testing of thin structures
The inductance/impedance due to thin metallic structures in non-destructive
testing (NDT) is difficult to evaluate. In particular, in Finite Element Method
(FEM) eddy current simulation, an extremely fine mesh is required to accurately
simulate skin effects especially at high frequencies, and this could cause an
extremely large total mesh for the whole problem, i.e. including, for example,
other surrounding structures and excitation sources like coils. Consequently,
intensive computation requirements are needed. In this paper, an
equivalent-effect phenomenon is found, which has revealed that alternative
structures can produce the same effect on the sensor response, i.e. mutual
impedance/inductance of coupled coils if a relationship (reciprocal
relationship) between the electrical conductivity and the thickness of the
structure is observed. By using this relationship, the mutual
inductance/impedance can be calculated from the equivalent structures with much
fewer mesh elements, which can significantly save the computation time. In eddy
current NDT, coils inductance/impedance is normally used as a critical
parameter for various industrial applications, such as flaw detection, coating
and microstructure sensing. Theoretical derivation, measurements and
simulations have been presented to verify the feasibility of the proposed
phenomenon
Physical Multi-Layer Phantoms for Intra-Body Communications
This paper presents approaches to creating tissue mimicking materials that
can be used as phantoms for evaluating the performance of Body Area Networks
(BAN). The main goal of the paper is to describe a methodology to create a
repeatable experimental BAN platform that can be customized depending on the
BAN scenario under test. Comparisons between different material compositions
and percentages are shown, along with the resulting electrical properties of
each mixture over the frequency range of interest for intra-body
communications; 100 KHz to 100 MHz. Test results on a composite multi-layer
sample are presented confirming the efficacy of the proposed methodology. To
date, this is the first paper that provides guidance on how to decide on
concentration levels of ingredients, depending on the exact frequency range of
operation, and the desired matched electrical characteristics (conductivity vs.
permittivity), to create multi-layer phantoms for intra-body communication
applications
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