Ali Ayazi

High-throughput single-microparticle imaging flow analyzer

Optical microscopy is one of the most widely used diagnostic methods in scientific, industrial, and biomedical applications. However, while useful for detailed examination of a small number (< 10,000) of microscopic entities, conventional optical microscopy is incapable of statistically relevant screening of large populations (> 100,000,000) with high precision due to its low throughput and limited digital memory size. We present an automated flow-through single-particle optical microscope that overcomes this limitation by performing sensitive blur-free image acquisition and nonstop real-time image-recording and classification of microparticles during high-speed flow. This is made possible by integrating ultrafast optical imaging technology, self-focusing microfluidic technology, optoelectronic communication technology, and information technology. To show the system’s utility, we demonstrate high-throughput image-based screening of budding yeast and rare breast cancer cells in blood with an unprecedented throughput of 100,000 particles/s and a record false positive rate of one in a million.

Obesity and gastroesophageal reflux: quantifying the association between body mass index, esophageal acid exposure, and lower esophageal sphincter status in a large series of patients with reflux symptoms.

IntroductionObesity and gastroesophageal reflux disease (GERD) are increasingly important health problems. Previous studies of the relationship between obesity and GERD focus on indirect manifestations of GERD. Little is known about the association between obesity and objectively measured esophageal acid exposure. The aim of this study is to quantify the relationship between body mass index (BMI) and 24-h esophageal pH measurements and the status of the lower esophageal sphincter (LES) in patients with reflux symptoms.MethodsData of 1,659 patients (50% male, mean age 51 ± 14) referred for assessment of GERD symptoms between 1998 and 2008 were analyzed. These subjects underwent 24-h pH monitoring off medication and esophageal manometry. The relationship of BMI to 24-h esophageal pH measurements and LES status was studied using linear regression and multiple regression analysis. The difference of each acid exposure component was also assessed among four BMI subgroups (underweight, normal weight, overweight, and obese) using analysis of variance and covariance.ResultsIncreasing BMI was positively correlated with increasing esophageal acid exposure (adjusted R2 = 0.13 for the composite pH score). The prevalence of a defective LES was higher in patients with higher BMI (p < 0.0001). Compared to patients with normal weight, obese patients are more than twice as likely to have a mechanically defective LES [OR = 2.12(1.63–2.75)].ConclusionAn increase in body mass index is associated with an increase in esophageal acid exposure, whether BMI was examined as a continuous or as a categorical variable; 13% of the variation in esophageal acid exposure may be attributable to variation in BMI.

Hybrid Dispersion Laser Scanner

Laser scanning technology is one of the most integral parts of todays scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanners broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points.

High-speed nanometer-resolved imaging vibrometer and velocimeter

Conventional laser vibrometers are incapable of performing multidimensional vibrometry at high speeds because they build on single-point measurements and rely on beam scanning, significantly limiting their utility and precision. Here we introduce a laser vibrometer that performs high-speed multidimensional imaging-based vibration and velocity measurements with nanometer-scale axial resolution without the need for beam scanning. As a proof-of-concept, we demonstrate real-time microscopic imaging of acoustic vibrations with 1 nm axial resolution, 1200 image pixels, and 30 ps dwell time at 36.7 MHz scan rate.

All-dielectric photonic-assisted wireless receiver

High Power Microwave (HPM) weapons and other sources of intense microwave power pose a growing threat to modern RF receivers. To address this problem, all-dielectric photonic-assisted receivers have been proposed and demonstrated. Here, we describe a new configuration of this type with 15 dB better sensitivity over prior designs. The complete lack of metal and electronics in the front-end offers immunity against damage from intense electromagnetic radiation. In this experiment, detection of C band electromagnetic signal at 6.54 GHz with a sensitivity of -112 dBm/Hz is demonstrated.

3D ultrafast laser scanner

Laser scanners are essential for scientific research, manufacturing, defense, and medical practice. Unfortunately, often times the speed of conventional laser scanners (e.g., galvanometric mirrors and acousto-optic deflectors) falls short for many applications, resulting in motion blur and failure to capture fast transient information. Here, we present a novel type of laser scanner that offers roughly three orders of magnitude higher scan rates than conventional methods. Our laser scanner, which we refer to as the hybrid dispersion laser scanner, performs inertia-free laser scanning by dispersing a train of broadband pulses both temporally and spatially. More specifically, each broadband pulse is temporally processed by time stretch dispersive Fourier transform and further dispersed into space by one or more diffractive elements such as prisms and gratings. As a proof-of-principle demonstration, we perform 1D line scans at a record high scan rate of 91 MHz and 2D raster scans and 3D volumetric scans at an unprecedented scan rate of 105 kHz. The method holds promise for a broad range of scientific, industrial, and biomedical applications. To show the utility of our method, we demonstrate imaging, nanometer-resolved surface vibrometry, and high-precision flow cytometry with real-time throughput that conventional laser scanners cannot offer due to their low scan rates.

Real-time image processor for detection of rare cells and particles in flow at 37 MHz line scans per second

We describe a real-time image processor that has enabled a new automated flow through microscope to screen cells in flow at 100,000 cells/s and a record false positive rate of one in a million. This unit is integrated with an ultrafast optical imaging modality known as serial time-encoded amplified microscopy (STEAM) for blur-free imaging of particles in high-speed flow. We show real-time image-based identification and screening of budding yeast cells and rare breast cancer cells in blood. The system generates E-slides (an electronic version of glass slides) on which particles of interest are digitally analyzed.

Dielectric Field Enhancer for Reconfiguring the Beam Pattern and Gain of an Antenna

We demonstrate the use of a dielectric rod, herein called a dielectric field enhancer (DFE), to reconfigure the radiation pattern and gain of an omni-directional antenna. To assess the DFE capability, we demonstrate an increase in gain of a preexisting antenna by near-field coupling with the DFE. The resulting field pattern is observed to be a hybrid of the DFEs directive beam pattern and that of the preexisting antenna. Measurements of a prototype DFE show a gain increase of at least 7.7 dB after the inclusion of the DFE, which compare well with simulations and therefore verify the capability of the DFE.

All-Dielectric Photonic-Assisted Wireless Receiver

We describe a new configuration of an all- dielectric wireless receiver with 15 dB better sensitivity over prior designs. The complete lack of metal and electronics in the front-end offers immunity against damage from intense electromagnetic radiation.

High-speed nanometer-resolved imaging-based laser vibrometry

We report a new type of laser vibrometer that performs high-speed imaging-based surface vibration measurements with ~1 nm axial resolution at a record scan rate of 36.7 MHz without the need for beam scanning.