About

Itai Cohen is a principal investigator in the Physics Department at Cornell University, leading the Itai Cohen Group. His research focuses on matter in motion, exploring the physical properties and behaviors of various materials through experimental and theoretical approaches. The group investigates phenomena related to the dynamics of complex systems, including soft matter and condensed matter physics. Professor Cohen's work involves studying the fundamental principles governing motion and interactions at the microscopic and macroscopic levels. His contributions aim to deepen understanding of how materials respond to forces and how their internal structures influence their behavior. As a faculty member at Cornell, he mentors graduate students and postdoctoral associates, fostering research that advances the field of physics and materials science.

Research topics

• Computer Science
• Materials science
• Optoelectronics
• Engineering
• Electrical engineering
• Nanotechnology
• Artificial Intelligence
• Physics
• Anatomy
• Medicine
• Biomedical engineering
• Mechanical engineering
• Composite material
• Pathology
• Chemistry

Selected publications

• Polarizer-Free Dye-Doped Liquid Crystal Sensors with High Precision

  ACS Sensors · 2025-03-10 · 3 citations

  article

  The surface-induced ordering of liquid crystals (LC) has been harnessed to detect a wide range of chemical and biological stimuli. In most sensor designs, the information-rich response of the LC is transduced from an analyte-triggered change in the out-of-plane orientation of the LC. Quantifying the out-of-plane LC orientation, however, is often complicated by simultaneous changes in the in-plane orientation of the LC when using polarized light for transduction. Here we introduce a sensing approach that combines a dichroic dye-doped LC (DDLC) with unpolarized light and a photodiode to achieve precise quantification of analyte-driven changes in the out-of-plane orientations of LCs. We benchmark the performance of the new methodology against polarizer-based approaches using a model amphiphilic analyte in aqueous solution and show that the DDLC provides a substantial reduction in the coefficient of variation (300% to less than 5%), an enhanced analytical sensitivity (0.16 to 3.73 μM–1), and an expanded dynamic range. In addition, when used to sense concentration gradients of analytes, the new approach distinguishes differences as small as 0.03 μM/μm over a dynamic range of 2 μM/μm, significantly outperforming conventional polarizer-based approaches that detect differences of 0.3 μM/μm over a dynamic range of 0.6 μM/μm. Overall, we conclude that the improved sensing performance and simpler implementation (no polarizers) of the DDLC approach, as compared to conventional LC sensors based on crossed-polars, will facilitate the deployment of LC sensors in diverse contexts, including the development of high-throughput screens for chemical formulations.

  PublisherDOI

• Drosophila DNp03 descending neurons serve as a hub within a flight saccade network

  Current Biology · 2025-12-12

  articleOpen access

  Animals rely on rapid sensorimotor processing to detect and respond to visual stimuli in their environment, yet how sensorimotor networks are organized to generate appropriate behaviors remains unclear. Here, we identify a bilateral pair of descending neurons (DNs), DNp03, as a hub for collision avoidance in flying flies. DNp03 receives visual information related to looming objects approaching on a collision course and connects directly and indirectly to motor neurons of the wings and neck, enabling the coordinated banked turn and head stabilization maneuvers of a rapid saccade. Although DNp03 can drive saccade-like behavior when optogenetically activated, naturalistic looming-evoked saccade behavior relies on a network of interconnected DNs that can partially compensate for DNp03 in its absence. The connectivity of this hierarchical network suggests DNp03 operates in parallel with two additional DN hubs that directly recruit subservient DNs to reinforce and expand behavioral outputs. We also find competition between the saccade network and descending pathways for landing behavior, where direct inhibitory connections from DNp03 reduce the likelihood a fly decides to land on, rather than turn away from, a looming object. Altogether, we provide a detailed mapping of one key sensorimotor pathway from visual inputs to motor outputs to demonstrate how even rapid, innate sensorimotor transformations rely on complex networks. These findings reveal intricate interconnectivity and hierarchy in descending pathways, a strategy that may represent a general principle of motor control across species.

  PublisherDOI

• Rigidity transitions in anisotropic networks: a crossover scaling analysis

  Soft Matter · 2025-01-01 · 2 citations

  articleOpen accessSenior author

  The onset of rigidity in anisotropic spring networks on a regular triangular lattice arises in at least two steps, with percolation of stress-supporting bonds occurring at different critical volume fractions along different directions.

  PublisherOA PDFDOI

• Universal Scaling Framework for Controlling Phase Behavior in Thickening and Jamming Suspensions

  Physical Review Letters · 2025-02-07 · 2 citations

  articleSenior author

  Recently, we proposed a universal scaling framework that shows shear thickening in dense suspensions is governed by the crossover between two critical points: one associated with frictionless isotropic jamming and a second corresponding to frictional shear jamming. Here, we show that orthogonal perturbations to the flows, an effective method for tuning shear thickening, can also be folded into this universal scaling framework. Specifically we show that the effect of adding orthogonal shear perturbations can be incorporated into the scaling variable via a multiplicative function, determined through our measurements, to achieve collapse of the entire thickening and dethickening dataset onto a single universal curve. We then show that this universal scaling framework can be used to control the phase behavior in thickening and jamming suspensions.

  PublisherDOI

• A multi-muscular, redundant strategy for free-flight roll stability

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-10-01

  preprintOpen accessSenior author

  Abstract Whether recovering after a gust of wind, or rapidly saccading away from an oncoming predator, fruit flies show remarkable aerial dexterity about their body roll axis. Here, we investigated the detailed wing kinematic changes during free-flight roll motion and probed the neuromuscular basis for such changes. Consistent with previous work, we observed that flies manipulated the stroke amplitude difference between their wings to control their roll angle. Here, we show that flies are capable of achieving such changes by altering the stroke amplitude of either or both of their wings. Further we found that during corrections flies can also take advantage of an aerodynamically significant change in the angle of attack of their uppermost wing. Curiously, these corrective wing changes cannot be eliminated when motor neurons hypothesized to be used during roll maneuvers (i1, i2, b1, b2, and b3) are individually inhibited. However, free-flight optogenetic manipulations and quasi-steady aerodynamic calculations show that each of these motor neurons individually can effect kinematic changes consistent with a roll correction. Combining this evidence with an analysis of haltere inputs found in the BANC connectome, we propose that the observed robustness could be the result of two sets of muscular redundancies that receive shared inputs from haltere sensory afferents: one set, containing b1 and b2, is able to increase the stroke amplitude of the lower wing; while the other set, containing i1, i2, and b3, is able to decrease the stroke amplitude and wing pitch angle of the upper wing. Because of the redundancy in the input sensory information and output wing motion in the muscles in each cluster, the fly is able to perform roll stability maneuvers even when one of the constituent motor neurons is inhibited. This framework proposes new ways fast aerial maneuverability can be implemented when dealing with the fly’s most unstable rotational degree of freedom.

  PublisherOA PDFDOI

• Single-cell type analysis of wing premotor circuits in the ventral nerve cord of Drosophila melanogaster

  eLife · 2025-05-06 · 1 citations

  preprintOpen access

  Abstract To perform most behaviors, animals must send commands from higher-order processing centers in the brain to premotor circuits that reside in ganglia distinct from the brain, such as the mammalian spinal cord or insect ventral nerve cord. How these circuits are functionally organized to generate the great diversity of animal behavior remains unclear. An important first step in unraveling the organization of premotor circuits is to identify their constituent cell types and create tools to monitor and manipulate these with high specificity to assess their functions. This is possible in the tractable ventral nerve cord of the fly. To generate such a toolkit, we used a combinatorial genetic technique (split-GAL4) to create 195 sparse transgenic driver lines targeting 196 individual cell types in the ventral nerve cord. These included wing and haltere motoneurons, modulatory neurons, and interneurons. Using a combination of behavioral, developmental, and anatomical analyses, we systematically characterized the cell types targeted in our collection. In addition, we identified correspondences between the cells in this collection and a recent connectomic data set of the ventral nerve cord. Taken together, the resources and results presented here form a powerful toolkit for future investigations of neuronal circuits and connectivity of premotor circuits while linking them to behavioral outputs.

  PublisherDOI

• Single-cell type analysis of wing premotor circuits in the ventral nerve cord of Drosophila melanogaster

  eLife · 2025-05-06 · 1 citations

  preprintOpen access

  Abstract To perform most behaviors, animals must send commands from higher-order processing centers in the brain to premotor circuits that reside in ganglia distinct from the brain, such as the mammalian spinal cord or insect ventral nerve cord. How these circuits are functionally organized to generate the great diversity of animal behavior remains unclear. An important first step in unraveling the organization of premotor circuits is to identify their constituent cell types and create tools to monitor and manipulate these with high specificity to assess their functions. This is possible in the tractable ventral nerve cord of the fly. To generate such a toolkit, we used a combinatorial genetic technique (split-GAL4) to create 195 sparse transgenic driver lines targeting 196 individual cell types in the ventral nerve cord. These included wing and haltere motoneurons, modulatory neurons, and interneurons. Using a combination of behavioral, developmental, and anatomical analyses, we systematically characterized the cell types targeted in our collection. In addition, we identified correspondences between the cells in this collection and a recent connectomic data set of the ventral nerve cord. Taken together, the resources and results presented here form a powerful toolkit for future investigations of neuronal circuits and connectivity of premotor circuits while linking them to behavioral outputs.

  PublisherDOI

• Hierarchical Self-Assembly of Magnetic Handshake Materials

  ACS Nano · 2025-04-11 · 2 citations

  article

  Through programmable self-assembly, simple building blocks can be made to form highly complex structures following local rules of interaction. However, materials systems that are most commonly utilized for programmable assembly often lack interactions that exhibit the strength, specificity, and long ranges, which would, as a result, allow for robust and rapid hierarchical self-assembly processes. "Magnetic handshake" building blocks resolve many of these challenges at once, incorporating strong, long-range, and specific magnetic interactions through patterning of magnetic dipoles onto rigid panels. When appropriately designed, the panels organize hierarchically: first into chains, and subsequently those chains combine to form dense stacks. Here, we examine differences in phase behavior and morphology for four panel types. We delineate how perpendicular chaining and stacking interactions between panels compete and how they can be manipulated to reverse the sequence of the hierarchical assembly pathway. Collectively, our work shows the enormous potential for using magnetic handshake materials for self-assembly of hierarchically organized complex structures.

  PublisherDOI

• Universal scaling solution for a rigidity transition: Renormalization group flows near the upper critical dimension

  Physical review. E · 2025-04-23

  article

  Rigidity transitions induced by the formation of system-spanning disordered rigid clusters, like the jamming transition, can be well described in most physically relevant dimensions by mean-field theories. A dynamical mean-field theory commonly used to study these transitions, the coherent potential approximation (CPA), shows logarithmic corrections in two dimensions. By solving the theory in arbitrary dimensions and extracting the universal scaling predictions, we show that these logarithmic corrections are a symptom of an upper critical dimension d_{upper}=2, below which the critical exponents are modified. We recapitulate Ken Wilson's phenomenology of the (4-ε)-dimensional Ising model, but with the upper critical dimension reduced to 2. We interpret this using normal form theory as a transcritical bifurcation in the RG flows and extract the universal nonlinear coefficients to make explicit predictions for the behavior near two dimensions. This bifurcation is driven by a variable that is dangerously irrelevant in all dimensions d>2 which incorporates the physics of long-wavelength phonons and low-frequency elastic dissipation. We derive universal scaling functions from the CPA sufficient to predict all linear response in randomly diluted isotropic elastic systems in all dimensions.

  PublisherDOI

• Magnetic decoupling as a proofreading strategy for high-yield, time-efficient microscale self-assembly

  Proceedings of the National Academy of Sciences · 2025-08-28

  articleOpen accessSenior authorCorresponding

  Life thrives due to its remarkable ability to create complex structures through the self-assembly of proteins, nucleic acids, and other biomolecules. Achieving such complex assemblies with the same level of fidelity, reproducibility, and advanced functionality in synthetic systems, however, has remained a grand challenge. One outstanding problem is the presence of parasitic products and long-lived intermediate states that slow the reaction process and limit the yield of the final product. Biology overcomes this challenge by proofreading to recognize and disassemble parasitic products. Such local checks, however, are currently difficult to implement in available self-assembly platforms. Here, we overcome this challenge by implementing a proofreading mechanism in a self-assembly platform. Specifically, we design intermediate states that strongly couple to an external force but a final product that is decoupled and thus highly stable to external driving, such that application of external forces selectively dissociates parasitic products. To implement this idea, we introduce lithographically patterned magnetic dipoles and an applied magnetic field to drive an assembly process similar to thermal self-assembly, but with additional controls. By applying patterns of magnetic driving that selectively destabilize parasitic states, we effectively implement a proofreading strategy to enable high-yield, time-efficient self-assembly. This realization of a general proofreading mechanism bridges the gap between artificial and biological self-assembly, paving the way for advanced self-assembled materials, with applications in next generation responsive materials, biomimetic devices, and microscale machines.

  PublisherDOI

Recent grants

• New paradigms for relating the microstructure of cartilage to its large scale mechanics: The Roles of Rigidity-Percolation and Double Gel Network Structure in Non-Linear Response

  NSF · $348k · 2015–2019

• CAREER: Using Colloidal Suspensions to Investigate the Role of Particle Dynamics in Heteroepitaxy and Melting

  NSF · $575k · 2011–2015

• DMREF: Collaborative Research: Digital Magnetic Handshake Materials, Structures, and Machines

  NSF · $1.2M · 2019–2023

• EFRI C3 SoRo: Micron-scale Morphing Soft-Robots for Interfacing With Biological Systems

  NSF · $2.0M · 2019–2025

• Using Confocal Rheometry to Investigate the Effect of Shear and Confinement on Colloidal Glasses

  NSF · $300k · 2006–2009

Frequent coauthors

• Lawrence J. Bonassar

  Cornell University

  63 shared

• Neil Y. C. Lin

  52 shared

• Meera Ramaswamy

  52 shared

• Paul L. McEuen

  Cornell University

  39 shared

• Abhishek Shetty

  Anton Paar (United States)

  37 shared

• James P. Sethna

  31 shared

• Ran Niu

  31 shared

• Edward Y. X. Ong

  30 shared

Labs

• Itai Cohen GroupPI

  matter in motion

Education

• PhD, Physics

  University of Chicago

  2001