Directional Resonant MEMS Acoustic Sensor and Associated Acoustic Vector Sensor.

This paper reports on the design, modeling, analysis, and evaluation of a micro-electromechanical systems acoustic sensor and the novel design of an acoustic vector sensor array (AVS) which utilized this acoustic sensor. This research builds upon previous work conducted to develop a small, lightweight, portable system for the detection and location of quiet or distant acoustic sources of interest. This study also reports on the underwater operation of this sensor and AVS.

Dual Band MEMS Directional Acoustic Sensor for Near Resonance Operation.

In this paper, we report on the design and characterization of a microelectromechanical systems (MEMS) directional sensor inspired by the tympana configuration of the parasitic fly . The sensor is meant to be operated at resonance and act as a natural filter for the undesirable frequency bands. By means of breaking the symmetry of a pair of coupled bridged membranes, two independent bending vibrational modes can be excited.

MEMS Underwater Directional Acoustic Sensor in Near Neutral Buoyancy Configuration.

A MEMS directional acoustic sensor housed in an air cavity and operated underwater in a near-neutral buoyancy configuration is demonstrated. The sensor consists of two wings connected by a bridge and attached to a substrate by two centrally mounted torsional legs. The frequency response showed two resonant peaks corresponding to a rocking mode (wings moving in opposite directions) and a bending mode (wings moving in the same direction).

Electronic phase shift measurement for the determination of acoustic wave DOA using single MEMS biomimetic sensor.

MEMS acoustic sensors have been developed to mimic the highly-accurate sound-locating system of the Ormia ochracea fly, which detects sound wavelengths much larger than its hearing organ. A typical ormia-based MEMS directional sound sensor possesses two coupled wings that vibrate in response to sound according to a superposition of its two main resonant modes, rocking and bending. Vibrations are transduced into electronic signals by interdigitated comb finger capacitors at each wing's end along with a capacitance measuring circuitry.

Fabrication of MEMS Directional Acoustic Sensors for Underwater Operation.

In this work, microelectromechanical systems (MEMS)-based directional acoustic sensors operating in an underwater environment are explored. The studied sensors consist of a free-standing single wing or two wings pivoted to a substrate. The sensors operate in a narrow frequency band determined by the resonant frequency of the mechanical structure.

Validated model of platelet slip at stenosis and device surfaces.

Platelets are central to thrombosis. However, it is unknown whether platelets slip at vascular or device surfaces. The presence of platelet slip at a surface would interrupt physical contact between the platelet and that surface, and therefore diminish adhesion and thrombosis.

MEMS terahertz-to-infrared band converter using frequency selective planar metamaterial.

A MEMS terahertz-to-infrared converter has been developed based on the unique properties of metamaterials that allow for selective control of the absorptivity and emissivity of the sensors. The converter consists of a sensing element structurally made of planar metamaterial membranes, connected to a substrate frame by four symmetrically-located thermal insulators. Upon THz absorption, the temperature of the sensing element increases and the outward infrared flux from the backside of the element is read by a commercial long-wave infrared camera.

Bio-Inspired Miniature Direction Finding Acoustic Sensor.

A narrowband MEMS direction finding sensor has been developed based on the mechanically coupled ears of the Ormia Ochracea fly. The sensor consists of two wings coupled at the middle and attached to a substrate using two legs. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone.

Bi-material terahertz sensors using metamaterial structures.

In this paper we report on the design, fabrication and characterization of terahertz (THz) bi-material sensors with metamaterial absorbers. MEMS fabrication-friendly SiOx and Al are used to maximize the bimetallic effect and metamaterial absorption at 3.8 THz, the frequency of a quantum cascade laser illumination source.

Narrowband terahertz emitters using metamaterial films.

In this article we report on metamaterial-based narrowband thermal terahertz (THz) emitters with a bandwidth of about 1 THz. Single band emitters designed to radiate in the 4 to 8 THz range were found to emit as high as 36 W/m(2) when operated at 400 °C. Emission into two well-separated THz bands was also demonstrated by using metamaterial structures featuring more complex unit cells.

Microelectromechanical systems bimaterial terahertz sensor with integrated metamaterial absorber.

This Letter describes the fabrication of a microelectromechanical systems (MEMS) bimaterial terahertz (THz) sensor operating at 3.8 THz. The incident THz radiation is absorbed by a metamaterial structure integrated with the bimaterial.

A novel noninvasive all optical technique to monitor physiology of an exercising muscle.

An all optical technique based on near-infrared spectroscopy and mid-infrared imaging (MIRI) is applied as a noninvasive, in vivo tool to monitor the vascular status of skeletal muscle and the physiological changes that occur during exercise. A near-infrared spectroscopy (NIRS) technique, namely, steady state diffuse optical spectroscopy (SSDOS) along with MIRI is applied for monitoring the changes in the values of tissue oxygenation and thermometry of an exercising muscle. The NIRS measurements are performed at five discrete wavelengths in a spectral window of 650-850 nm and MIRI is performed in a spectral window of 8-12 microm.

Real-time imaging using a 2.8 THz quantum cascade laser and uncooled infrared microbolometer camera.

Real-time imaging in the terahertz (THz) spectral range was achieved using a milliwatt-scale, 2.8 THz quantum cascade laser and an uncooled, 160 x 120 pixel microbolometer camera modified with Picarin optics. Noise equivalent temperature difference of the camera in the 1-5 THz frequency range was estimated to be at least 3 K, confirming the need for external THz illumination when imaging in this frequency regime.