Igor Bargatin
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View article: Moving Towards Data-Driven Departmental DEI
Moving Towards Data-Driven Departmental DEI Open
Faculty and staff can and do influence the climate of a department and achievement of students. Research shows the positive effects of choosing to implement evidence-based teaching practices like active learning and inclusive teaching, and…
View article: Numerical and experimental study on the addition of surface roughness to micro-propellers
Numerical and experimental study on the addition of surface roughness to micro-propellers Open
Micro aerial vehicles are making a large impact in applications such as search-and-rescue, package delivery, and recreation. Unfortunately, these diminutive drones are currently constrained to carrying small payloads, in large part because…
View article: Photophoretic Light-flyers with Germanium Coatings as Selective Absorbers
Photophoretic Light-flyers with Germanium Coatings as Selective Absorbers Open
The goal of ultrathin lightweight photophoretic flyers, or light-flyers for short, is to levitate continuously in Earth's upper atmosphere using only sunlight for propulsive power. We previously reported light-flyers that levitated by util…
View article: 3D photophoretic aircraft made from ultralight porous materials can carry kg-scale payloads in the mesosphere
3D photophoretic aircraft made from ultralight porous materials can carry kg-scale payloads in the mesosphere Open
We show that photophoretic aircraft would greatly benefit from a three-dimensional (3D) hollow geometry that pumps ambient air through sidewalls to create a high-speed jet. To identify optimal geometries, we developed a theoretical express…
View article: Minimizing the Ground Effect for Photophoretically Levitating Disks
Minimizing the Ground Effect for Photophoretically Levitating Disks Open
Photophoretic levitation is a propulsion mechanism in which lightweight objects can be lifted and controlled through their interactions with light. Since photophoretic forces on macroscopic objects are usually maximized at low pressures, t…
View article: Multiscale Photonic Emissivity Engineering for Relativistic Lightsail Thermal Regulation
Multiscale Photonic Emissivity Engineering for Relativistic Lightsail Thermal Regulation Open
The Breakthrough Starshot Initiative aims to send a gram-scale probe to Proxima Centuri B using a laser-accelerated lightsail traveling at relativistic speeds. Thermal management is a key lightsail design objective because of the intense l…
View article: Relativistic Light Sails Need to Billow
Relativistic Light Sails Need to Billow Open
We argue that light sails that are rapidly accelerated to relativistic velocities by lasers must be significantly curved in order to reduce their mechanical stresses and avoid tears. Using an integrated opto-thermo-mechanical model, we sho…
View article: Thermo-accelerative optimization of relativistic lightsails
Thermo-accelerative optimization of relativistic lightsails Open
The Breakthrough Starshot Initiative aims to send a gram-scale probe to Proxima Centuri B using a high-power laser-accelerated lightsail traveling at relativistic speeds. Thermal degradation is a key consideration in the design of lightsai…
View article: Enhancing the Photophoretic Lift Force at Low Reynolds Numbers using Three-Dimensional Porous Structures
Enhancing the Photophoretic Lift Force at Low Reynolds Numbers using Three-Dimensional Porous Structures Open
It is well documented that the lift force of hovering micro aerial vehicles can be enhanced by increasing their air-flow velocities. This is commonly accomplished using nozzles and other flow-manipulating geometries with Reynolds numbers a…
View article: Hollow AFM Cantilever with Holes
Hollow AFM Cantilever with Holes Open
Since its invention, atomic force microscopy (AFM) has enhanced our understanding of physical and biological systems at sub-micrometer scales [...]
View article: Demonstration of Atmospheric-Pressure Radiometer with Metamaterial Vanes
Demonstration of Atmospheric-Pressure Radiometer with Metamaterial Vanes Open
We report a Crookes radiometer that rotates at atmospheric pressure using architected microporous dielectric plates, known as nanocardboard, as vanes [1,2]. Compared to most light mills working at tens of Pascals [3,4], the functionality a…
View article: Controlled Light-Driven Levitation of Macroscopic Plates
Controlled Light-Driven Levitation of Macroscopic Plates Open
Photophoretic or light-driven levitation has been studied extensively in the context of the motion of illuminated micron-sized particles, such as dust grains in the atmosphere under sunlight [1,2], and in relation to Crooks radiometers [3]…
View article: Progress Toward High Power Output in Thermionic Energy Converters
Progress Toward High Power Output in Thermionic Energy Converters Open
Thermionic energy converters are solid‐state heat engines that have the potential to produce electricity with efficiencies of over 30% and area‐specific power densities of 100 Wcm −2 . Despite this prospect, no prototypes reported in the l…
View article: Photophoretic Levitation of Macroscopic Nanocardboard Plates
Photophoretic Levitation of Macroscopic Nanocardboard Plates Open
Scaling down miniature rotorcraft and flapping‐wing flyers to sub‐centimeter dimensions is challenging due to complex electronics requirements, manufacturing limitations, and the increase in viscous damping at low Reynolds numbers. Photoph…
View article: Upper bound for the power outputs of linear vibrational power harvesters: translational vs. rotational geometries
Upper bound for the power outputs of linear vibrational power harvesters: translational vs. rotational geometries Open
Inertial harvesters utilize the motion of a translating or rotating mass to scavenge power from ambient vibrations. For translational harvesters, analytical expressions describing the influence of size on the output power of these harveste…
View article: Surface Photovoltage-Induced Ultralow Work Function Material for Thermionic Energy Converters
Surface Photovoltage-Induced Ultralow Work Function Material for Thermionic Energy Converters Open
Low work function materials are essential for efficient thermionic energy converters (TECs), electronics, and electron emission devices. Much effort has been put into finding thermally stable material combinations that exhibit low work fun…
View article: Micron-gap spacers with ultrahigh thermal resistance and mechanical robustness for direct energy conversion
Micron-gap spacers with ultrahigh thermal resistance and mechanical robustness for direct energy conversion Open
In thermionic energy converters, the absolute efficiency can be increased up to 40% if space-charge losses are eliminated by using a sub-10-µm gap between the electrodes. One practical way to achieve such small gaps over large device areas…
View article: KNUDSEN-PUMP-BASED MICRO-HOVERCRAFTS
KNUDSEN-PUMP-BASED MICRO-HOVERCRAFTS Open
We introduce polymer-membrane micro-hovercrafts which utilize incident light to generate the lift force.The light is absorbed by a carbon nanotube layer on one side of the membrane resulting in a temperature gradient along the thickness of…
View article: HOLLOW FLEXURAL RESONATORS WITH NANOSCALE THICKNESS
HOLLOW FLEXURAL RESONATORS WITH NANOSCALE THICKNESS Open
Hollow resonators with nanoscale thickness have similar resonance frequencies but much lower spring constants and quality factors than solid resonators of the same dimensions, offering unique advantages in sensor applications.We report hol…
View article: TWO-LAYER PLATE MECHANICAL METAMATERIALS
TWO-LAYER PLATE MECHANICAL METAMATERIALS Open
We present the fabrication and characterization of plates made from two ultrathin layers and capable of withstanding repeated extreme mechanical deformation.The ultrathin layers, one flat and the other corrugated, are less than 100 nm thic…