Metin Sitti

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Sitti

First Name

Metin

ORCID

0000-0001-8249-3854

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Publications1 - 10 of 265

Optofluidic three-dimensional microfabrication and nanofabrication
Lyu, Xianglong; Lei, Wenhai; Gardi, Gaurav; et al. (2026)
Nature
Three-dimensional (3D) microfabrication/nanofabrication technologies have revolutionized various fields by enabling the precise construction of complex microstructures/nanostructures1, 2, 3, 4, 5-6. However, existing methods face challenges in fabricating intricate 3D architectures from a diverse range of materials beyond conventional polymers. Here we introduce a universal 3D microfabrication/nanofabrication strategy compatible with a broad range of materials by precisely manipulating optofluidic interactions within a confined 3D space, enabling the creation of volumetric, free-form 3D microstructures/nanostructures. A femtosecond-laser-induced heating spot generates a localized thermal gradient, providing precise spatiotemporal control over optofluidic interactions of the nanoparticle-laden dispersions. This enables the rapid and highly localized assembly of nanoparticles with diverse shapes and compositions-including metals, metal oxides, carbon nanomaterials and quantum dots-into complex 3D microstructures. To demonstrate its versatility, we fabricate multifunctional microdevices, such as 3D microfluidic valves with size-selective sieving functionality, achieving fast separation of microparticles/nanoparticles with distinct dimensions, as well as microrobots integrated with four distinct functional materials, achieving multimodal locomotion powered by different external stimuli. This optofluidic 3D microfabrication/nanofabrication method unlocks new opportunities for advanced material innovation and miniaturized device development, paving the way for broad applications in colloidal robotics7, microphotonics/nanophotonics, catalysis and microfluidics.
Applications of AFM based nanorobotic systems
Xie, Hui; Onal, Cagdas; Régnier, Stéphane; et al. (2011)
Springer Tracts in Advanced Robotics ~ Atomic Force Microscopy Based Nanorobotics
This chapter deals with potential applications of atomic force microscopy based robotic system. In a first part, a flexible robotic system developed for multi-scale manipulation and assembly from nanoscale to microscale is presented. This system is based on the principle of atomic force microscopy and comprises two individually functionalized cantilevers. After reconfiguration, the robotic system could be used for pick-and-place manipulation from nanoscale to the scale of several micrometers, as well as parallel imaging/nanomanipulation. Flexibilities and manipulation capabilities of the developed system are validated by pick-and-placemanipulation of microspheres and silicon nanowires to build three-dimensional micro/nano structures in ambient conditions.Moreover, the capability of parallel nanomanipulation is certified by high-efficiency fabrication of a two-dimensional pattern with nanoparticles. Complicated micro/nano manipulation and assembly can be reliably and efficiently performed using the proposed flexible robotic system.
Stiffness-tunable velvet worm-inspired soft adhesive robot
Min, Hyeongho; Bae, Daebeom; Jang, Siyeon; et al. (2024)
Science Advances
Considering the characteristics and operating environment of remotely controlled miniature soft robots, achieving delicate adhesion control over various target surfaces is a substantial challenge. In particular, the ability to delicately grasp wrinkled and soft biological and nonbiological surfaces with low preload without causing damage is essential. The proposed adhesive robotic system, inspired by the secretions from a velvet worm, uses a structured magnetorheological material that exhibits precise adhesion control with stability and repeatability by the rapid stiffness change controlled by an external magnetic field. The proposed adhesion protocol involves controlling soft-state adhesion, maintaining a large contact area, and enhancing the elastic modulus, and the mechanical structure enhances the effectiveness of this protocol. Demonstrations of the remote adhesive robot include stable transportation in soft and wet organs, unscrewing a nut from a bolt, and supporting mouse tumor removal surgery. These results indicate the potential applicability of the soft adhesive robot in biomedical engineering, especially for targeting small-scale biological tissues and organisms.
Three-Dimensional Robotic Manipulation and Transport of Micro-Scale Objects by a Magnetically Driven Capillary Micro-Gripper
Giltinan, Joshua; Diller, Eric; Mayda, Cagil; et al. (2014)
2014 IEEE International Conference on Robotics and Automation (ICRA)
One major challenge for untethered micro-scale mobile robotics is the manipulation of external objects in the robot's three-dimensional (3D) work environment. Here, we present a method to use the capillary force at a solid-liquid-gas interface to reversibly attach objects to a mobile magnetic microrobot. This is accomplished by the addition of a cavity in the hydrophobic microrobot, in which an air bubble is captured when the microrobot is placed in a water environment. The extension of the air bubble from the cavity is adjusted dynamically by controlling the pressure of the workspace environment. A peak switching ratio between the maximum and minimum gripping forces of 14:1 is shown for controlled attachment/detachment experiments, which allows for reliable pick-and-place operation. This work introduces an analytical capillary adhesion model and demonstrates control of the bubble size for pick-and-place gripping. A proof-of-concept demonstration of 3D manipulation in a fluidic environment shows the potential of capillary gripping for future use in confined environments such as inside microfluidic devices for transportation or assembly of hydrophobic objects.
A New Biomimetic Adhesive for Therapeutic Capsule Endoscope Applications in the Gastrointestinal Tract
Glass, Paul; Sitti, Metin; Appasamy, Ragunath (2007)
Gastrointestinal Endoscopy
Nanomanipulation with 3D visual and force feedback using atomic force microscopes
Vogl, Wolfgang; Sitti, Metin; Zäh, Michael F. (2004)
4th IEEE International Conference on Nanotechnology
Atomic force microscopes (AFM) have been widely used for nanomanipulation throughout the last decade. Due to the design of AFMs, forces exerted on the AFM-tip cannot be resolved in 3D and no visual feedback can be obtained during manipulation. In this paper, we present an augmented reality approach for nanomanipulation interfaces, in which nano-scale 3D topography and force information sensed by the AFM-probe are blended with real time simulations. The sample surface is modeled with a spline-based geometry model, upon which a collision detection algorithm determines, whether and how the spherical AFM-tip penetrates the surface. Based on these results, surface deformations can be simulated in real-time and - up to now impossible - decoupled 3D force sensing can be achieved.
Fiberbot: A Miniature Crawling Robot Using a Directional Fibrillar Pad
Han, Yuanfeng; Marvi, Hamidreza; Sitti, Metin (2015)
2015 IEEE International Conference on Robotics and Automation (ICRA)
Vibration-driven locomotion has been widely used for crawling robot studies. Such robots usually have a vibration motor as the actuator and a fibrillar structure for providing directional friction on the substrate. However, there has not been any studies about the effect of fiber structure on robot crawling performance. In this paper, we develop Fiberbot, a custom made mini vibration robot, for studying the effect of fiber angle on robot velocity, steering, and climbing performance. It is known that the friction force with and against fibers depends on the fiber angle. Thus, we first present a new fabrication method for making millimeter scale fibers at a wide range of angles. We then show that using 30° angle fibers that have the highest friction anisotropy (ratio of backward to forward friction force) among the other fibers we fabricated in this study, Fiberbot speed on glass increases to 13.8±0.4 cm/s (compared to ν = 0.6±0.1 cm/s using vertical fibers). We also demonstrate that the locomotion direction of Fiberbot depends on the tilting direction of fibers and we can steer the robot by rotating the fiber pad. Fiberbot could also climb on glass at inclinations of up to 10° when equipped with fibers of high friction anisotropy. We show that adding a rigid tail to the robot it can climb on glass at 25° inclines. Moreover, the robot is able to crawl on rough surfaces such as wood (ν = 10.0±0.2 cm/s using 30° fiber pad). Fiberbot, a low-cost vibration robot equipped with a custom-designed fiber pad with steering and climbing capabilities could be used for studies on collective behavior on a wide range of topographies as well as search and exploratory missions.
A legged anchoring mechanism for capsule endoscopes using micropatterned adhesives
Glass, Paul; Cheung, Eugene; Sitti, Metin (2008)
IEEE Transactions on Biomedical Engineering
This paper presents a new concept for an anchoring mechanism to enhance existing capsule endoscopes. The mechanism consists of three actuated legs with compliant feet lined with micropillar adhesives to be pressed into the intestine wall to anchor the device at a fixed location. These adhesive systems are inspired by gecko and beetle foot hairs. Single-leg and full capsule mathematical models of the forces generated by the legs are analyzed to understand capsule performance. Empirical friction models for the interaction of the adhesives with an intestinal substrate were experimentally determined in vitro using dry and oil-coated elastomer micropillar arrays with 140 mum pillar diameter, 105 mum spacing between pillars, and an aspect ratio of 1:1 on fresh porcine small intestine specimens. Capsule prototypes were also tested in a simulated intestine environment and compared with predicted peristaltic loads to assess the viability of the proposed design. The experimental results showed that a deployed 10 gr capsule robot can withstand axial peristaltic loads and anchor reliably when actuation forces are greater than 0.27 N using dry micropillars. Required actuation forces may be reduced significantly by using micropillars coated with a thin silicone oil layer.
Capillary trapping of various nanomaterials on additively manufactured scaffolds for 3D micro-/nanofabrication
Lyu, Xianglong; Zheng, Zhiqiang; Shiva, Anitha; et al. (2024)
Nature Communications
High-precision additive manufacturing technologies, such as two-photon polymerization, are mainly limited to photo-curable polymers and currently lacks the possibility to produce multimaterial components. Herein, we report a physically bottom-up assembly strategy that leverages capillary force to trap various nanomaterials and assemble them onto three-dimensional (3D) microscaffolds. This capillary-trapping strategy enables precise and uniform assembly of nanomaterials into versatile 3D microstructures with high uniformity and mass loading. Our approach applies to diverse materials irrespective of their physiochemical properties, including polymers, metals, metal oxides, and others. It can integrate at least four different material types into a single 3D microstructure in a sequential, layer-by-layer manner, opening immense possibilities for tailored functionalities on demand. Furthermore, the 3D microscaffolds are removable, facilitating the creation of pure material-based 3D microstructures. This universal 3D micro-/nanofabrication technique with various nanomaterials enables the creation of advanced miniature devices with potential applications in multifunctional microrobots and smart micromachines.
Roadmap for Clinical Translation of Mobile Microrobotics
Bozuyuk, Ugur; Wrede, Paul; Yildiz, Erdost; et al. (2024)
Advanced Materials
Medical microrobotics is an emerging field to revolutionize clinical applications in diagnostics and therapeutics of various diseases. On the other hand, the mobile microrobotics field has important obstacles to pass before clinical translation. This article focuses on these challenges and provides a roadmap of medical microrobots to enable their clinical use. From the concept of a "magic bullet" to the physicochemical interactions of microrobots in complex biological environments in medical applications, there are several translational steps to consider. Clinical translation of mobile microrobots is only possible with a close collaboration between clinical experts and microrobotics researchers to address the technical challenges in microfabrication, safety, and imaging. The clinical application potential can be materialized by designing microrobots that can solve the current main challenges, such as actuation limitations, material stability, and imaging constraints. The strengths and weaknesses of the current progress in the microrobotics field are discussed and a roadmap for their clinical applications in the near future is outlined.

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