About

Igor Bargatin is an Associate Professor in the Department of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania. He serves as the Principal Investigator of the Bargatin Group, which focuses on research areas including plate mechanical metamaterials, photophoretic levitation, and thermionic energy converters. His group conducts experimental and theoretical studies on ultrathin, ultralight structures, exploring their applications in atmospheric research, space exploration, and energy conversion technologies. The research involves advanced nano- and micro-fabrication techniques to develop novel materials and devices such as thermionic spacers and levitating structures. Professor Bargatin's work integrates interdisciplinary approaches to address challenges in energy efficiency and innovative material design.

Research topics

• Materials science
• Physics
• Computer Science
• Engineering
• Mechanical engineering
• Aerospace engineering
• Nanotechnology
• Meteorology
• Optics
• Electrical engineering
• Mechanics
• Engineering physics
• Astrobiology
• Nuclear engineering
• Thermodynamics
• Aeronautics
• Environmental science

Selected publications

• Tether-Based Architecture for Solar-Powered Orbital Data Centers

  2026-01-08

  preprintOpen access1st authorCorresponding

  We propose a tether-based structural architecture for orbital data centers operating in Dawn-Dusk Sun-Synchronous (DDSS) orbits under continuous sunlight. These space-based data centers, powered solely by solar energy, could provide multi-megawatt computing for artificial intelligence (AI) inference with minimal latency to Earth. The proposed design uses a tethered chain of computing nodes with photovoltaic panels to achieve uninterrupted ~2–20 MW of computing power, and employs radiative cooling and integrated shielding to manage heat and radiation. We detail the system architecture, including mass budgets, passive attitude control, and the dynamics induced by micrometeoroid collisions.

  PublisherOA PDFDOI

• Low-Power Solar Sail Control Using In-Plane Forces From Tunable Buckling of Kirigami Films

  2026-01-08

  articleSenior author

  We present a proof-of-concept study showing that buckled aluminized polyimide films perforated with millimeter-scale cuts can redirect normally incident light obliquely and generate net in-plane force components parallel to the global solar sail surface. We use finite element simulations to obtain the buckled shapes of different periodic unit cell geometries and apply ray optics modeling to compute the resulting light-pressure forces. The simulations show that the buckled kirigami surfaces reflect light into different directions, producing a net in-plane force parallel to the direction of stretching. We verify these trends experimentally by illuminating a tensioned kirigami sample with a laser and observing reflected beam patterns consistent with the ray optics simulations. These results suggest that kirigami films may offer a low-power and lightweight way to achieve controllable in-plane forces for solar sail steering.

  PublisherDOI

• Exploring Tunable Buckling for Solar Sail Applications

  ScholarlyCommons (University of Pennsylvania) · 2025-09-15

  otherOpen access

  By harnessing the momentum of sunlight solar sails offer a lightweight alternative to chemical propulsion for long-duration space missions. Intuitively, larger sails are able to harness more power. However, as sails get larger they require more time and energy to rotate, making precise orientation and travel more time consuming and difficult. This project investigates tunable buckling in kirigami-inspired films as a way to achieve directional control without rotating the entire structure. Through light detection image-processing and a thermal sensor the relationship between in-plane reflected power and strain was quantified. sensor, the relationship between in-plane reflected power and applied strain was quantified. Results from rotating triangle geometries demonstrate controllable inclination angles and measurable shifts in reflected intensity with strain. These findings indicate that strain-induced buckling can serve as an effective actuation mechanism for solar sails. Future work aims to refine calibration accuracy and develop a dimensionless coefficient relating incident optical power to in-plane force across kirigami geometries.

  Publisher

• Kirigami Film Reflector for Deployable Space Antennas

  ArXiv.org · 2025-12-05

  preprintOpen accessSenior author

  We propose a low-pretension reflective kirigami film as a material for the reflective surfaces of large deployable space reflector antennas with an operating frequency around 10 GHz. The kirigami cut pattern is based on the well-known rotating squares pattern but is augmented with diagonal cuts to enhance stretchability and allow control over the effective Poisson's ratio. Using finite element simulations, we analyzed how the geometric parameters of this pattern affected the reflectance of the film and the pretension required to resist thermal deformations. Tensile testing of selected designs, which are approximately half the weight of traditional metallic meshes, demonstrated a substantial reduction in the needed pretension to ~0.5 N/m and as low as ~0.1 N/m. Such low pretension represents an order-of-magnitude improvement over traditional metallic mesh reflectors and could enable the use of lighter antenna trusses. Free-space reflectance measurements also show that these perforated films can maintain power reflectance exceeding 90% at 10 GHz under the strains expected in the deployed configuration.

  PublisherOA PDFDOI

• Design of Kirigami-Inspired Metamaterials for Stretchable Space Antennas

  Scholarly Commons (University of Pennsylvania) · 2025-08-25

  otherOpen access

  Deployable space antennas demand materials that are lightweight, compact, and highly stretchable. This work explores kirigami-inspired mechanical metamaterials as potential reflector surfaces as alternatives to AstroMesh system. Using Finite Element Analysis (FEA) and physical prototyping, we evaluated five geometries by stretchability, isotropicity and manufacturability with the corresponding indices. Results reveal that additional diagonal and auxiliary cuts significantly improve stretchability but can reduce isotropicity. Geometry 5 achieved the highest stretchability, while Geometry 3 achieved the highest manufacturability, which demonstrates the balance required between mechanical properties and fabrication feasibility. Overall, we demonstrated that kirigami metamaterials hold strong promise for lightweight reflector applications, while also providing broader design insights for kirigami metamaterials.

  Publisher

• Levitating platform could ride sunlight into the ‘ignorosphere’

  Nature · 2025-08-13

  article1st authorCorresponding
  PublisherDOI

• Lightweight photophoretic flyers with germanium coatings as selective absorbers

  Physical Review Applied · 2024-04-09 · 5 citations

  articleSenior author

  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 utilizing differences in thermal accommodation coefficient between the top and bottom of a thin film, made possible by coating their lower surfaces with carbon nanotubes (CNTs). Such designs, though successful, had relatively high thermal emissivity (>0.5), which prevented them from achieving high temperatures and resulted in their transferring relatively low amounts of momentum to the surrounding gas. To address this issue, we have developed light flyers with ultrathin undoped germanium layers that selectively absorb nearly 80% of visible light but are mostly transparent in the thermal infrared, with an average thermal emissivity of 0.1. Our experiments show that germanium-coated light flyers could levitate at up to 43% lower light irradiances than mylar-CNT disks with identical sizes. In addition, we simulated our experiments using a semiempirical model, which allowed us to predict that our 2-cm-diameter disk-shaped germanium-coated light flyers can levitate in the mesosphere (altitudes 67--75 km) under the natural sunlight (1.36 kW/${\mathrm{m}}^{2}$). Similar ultrathin selective-absorber coatings can also be applied to three-dimensional light flyers shaped like solar balloons, allowing them to carry significant payloads and thereby revolutionize long-term atmospheric exploration of Earth or Mars.

  PublisherDOI

• Three-dimensional photophoretic aircraft made from ultralight porous materials can carry kilogram-scale payloads in the mesosphere

  Physical Review Applied · 2024-11-27 · 5 citations

  articleSenior author

  We show theoretically that photophoretic aircraft would greatly benefit from a three-dimensional hollow geometry that pumps ambient air through sidewalls to create a high-speed jet. To identify optimal geometries, we developed a theoretical expression for the lift force based on both Stokes (low Reynolds number) and momentum (high Reynolds number) theory and validated it using finite-element fluid-dynamics simulations. We then systematically varied geometric parameters, including Knudsen pump porosity, to minimize the operating altitude or maximize the payload. Assuming that large vehicles can be made from nanocardboard material, as previously demonstrated at smaller scales, the minimum altitude such vehicles can levitate at is approximately 55 km, while the payload can reach approximately 1 kg at an altitude of 80 km for vehicles with a 10 m diameter. In all cases, the maximum areal density of the sidewalls cannot exceed a few grams per square meter, demonstrating the need for ultralight porous materials.

  PublisherDOI

• Knudsen Pump- and Solar Buoyancy-Based Propulsion for Atmospheric and Martian Exploration

  2024-01-04 · 2 citations

  articleSenior author

  In this work, we propose a vehicle that is powered solely by light, has no moving parts, and is capable of carrying kg-scale payloads from 0 to 80 km above Earth’s surface. The vehicle originally employed 2D porous centimeter-scale plates that utilize photophoresis—the light-induced movement of gas particles. Photophoresis exploits temperature gradients created by sunlight to pump air through channels spanning the thickness of such plates, creating lift for payloads. We developed a model that predicts several kilograms of payload capabilities for 3D structures with radii of tens of meters. These structures also function as solar balloons, providing lift at altitudes below 50 km, while photophoretic forces provide most of the lift to the mesosphere (50-80 km). We also report experimental results showcasing solar buoyancy, as well as initial proof-of-concept reduced pressure testing. Proposed applications include extensive atmospheric measurements of winds, gas concentrations, and other state properties that are difficult to measure remotely.

  PublisherDOI

• Moving Towards Data-Driven Departmental DEI

  2024-02-06 · 1 citations

  articleOpen accessSenior author

  Abstract 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 having a growth mindset in relation to the abilities of students. However, research also shows that the local climate in a department could cause students of color to be driven from STEM, or that a chilly climate could have a disproportionate impact on female students. And while the focus of Diversity, Equity, and Inclusion (DEI) efforts tends to be on women and under-represented minorities (URMs, defined as non-white, non-Asian), populations with representation at or above the demographics of the general population face their own challenges. In this paper, we describe recent efforts in the Mechanical Engineering and Applied Mechanics (MEAM) Department at the University of Pennsylvania to address these issues. Most of our initial efforts in this area have focused on the undergraduate population as well as their intersection with faculty and staff. We have started exploring the departmental structures and practices and have some initial demographic data on students and faculty. We are interested in exploring how retention, graduation, and achievement in general overlap and intersect with gender, race, and socio-economic status. We have also recently implemented a DEI Scholars program that further engages undergraduate and graduate students in this process. This initial work establishes baseline numbers and describes the first cohort we will track from acceptance through graduation. It is our aim that sharing these early efforts may encourage others to take on similar endeavors, and will also provide a reference point for future work of ours in this area.

  PublisherOA PDFDOI

Recent grants

• CAREER: Thermal transport in ultrathin metamaterials: Enabling levitation at the macroscale

  NSF · $500k · 2019–2025

Frequent coauthors

• C. Marcoux

  CEA LETI

  60 shared

• Sébastien Hentz

  CEA Grenoble

  60 shared

• Laurent Duraffourg

  CEA LETI

  60 shared

• Éric Colinet

  60 shared

• Philippe Andreucci

  CEA LETI

  60 shared

• Guillaume Jourdan

  CEA LETI

  30 shared

• C Kharrat

  Institut polytechnique de Grenoble

  30 shared

• Simon Labarthe

  UMR BIOdiversity, GEnes & Communities

  30 shared

Labs

• Bargatin GroupPI

Education

• Ph.D., Mechanical Engineering

  Massachusetts Institute of Technology

  2003

• M.S., Mechanical Engineering

  Massachusetts Institute of Technology

  1999

• B.S., Mechanical Engineering

  University of California, Berkeley

  1998