682 results
(View BibTeX file of all listed publications)
2024
A simple quantitative model of neuromodulation, Part I: Ion flow through neural ion channels
Werneck, L., Han, M., Yildiz, E., Keip, M., Sitti, M., Ortiz, M.
Journal of the Mechanics and Physics of Solids, 182, pages: 105457, 2024 (article)
We develop a simple model of ionic current through neuronal membranes as a function of membrane potential and extracellular ion concentration. The model combines a simplified Poisson–Nernst–Planck (PNP) model of ion transport through individual ion channels with channel activation functions calibrated from ad hoc in-house experimental data. The simplified PNP model is validated against bacterial gramicidin A ion channel data. The calibrated model accounts for the transport of calcium, sodium, potassium, and chloride and exhibits remarkable agreement with the experimentally measured current–voltage curves for the differentiated human neural cells.
Wireless flow-powered miniature robot capable of traversing tubular structures
Hong, C., Wu, Y., Wang, C., Ren, Z., Wang, C., Liu, Z., Hu, W., Sitti, M.
Science Robotics, 9(88):eadi5155, 2024 (article)
Wireless millimeter-scale robots capable of navigating through fluid-flowing tubular structures hold substantial potential for inspection, maintenance, or repair use in nuclear, industrial, and medical applications. However, prevalent reliance on external powering constrains these robots’ operational range and applicable environments. Alternatives with onboard powering must trade off size, functionality, and operation duration. Here, we propose a wireless millimeter-scale wheeled robot capable of using environmental flows to power and actuate its long-distance locomotion through complex pipelines. The flow-powering module can convert flow energy into mechanical energy, achieving an impeller speed of up to 9595 revolutions per minute, accompanied by an output power density of 11.7 watts per cubic meter and an efficiency of 33.7%. A miniature gearbox module can further transmit the converted mechanical energy into the robot’s locomotion system, allowing the robot to move against water flow at an average rate of up to 1.05 meters per second. The robot’s motion status (moving against/with flow or pausing) can be switched using an external magnetic field or an onboard mechanical regulator, contingent on different proposed control designs. In addition, we designed kirigami-based soft wheels for adaptive locomotion. The robot can move against flows of various substances within pipes featuring complex geometries and diverse materials. Solely powered by flow, the robot can transport cylindrical payloads with a diameter of up to 55% of the pipe’s diameter and carry devices such as an endoscopic camera for pipeline inspection, a wireless temperature sensor for environmental temperature monitoring, and a leak-stopper shell for infrastructure maintenance.
Clinical translation of wireless soft robotic medical devices
Wang, T., Wu, Y., Yildiz, E., Kanyas, S., Sitti, M.
Nature Reviews Bioengineering, 2024 (article)
Small-scale wireless soft robotics can be designed as implantable, interventional or wearable devices for various biomedical applications. Their flexibility, dexterity, adaptability and safe interactions with biological environments make them promising candidates for enabling precise and remote healthcare and disease diagnosis. However, the clinical translation of wireless soft robotic medical devices remains challenging. In this Review, we provide a comprehensive overview of the robotic technologies, the navigation methods, the dexterous functions and the translational challenges of wireless soft robotic medical devices. We first discuss safety and biocompatibility from a biological and technical perspective and then examine navigation methods for overcoming biological barriers for delivery, mobility and retrieval, highlighting dexterous medical functions at small scales. Finally, we identify key product development challenges, as well as the regulatory and ethical considerations that should be addressed to enable the clinical translation of wireless soft robotic medical devices.
Janus microparticles-based targeted and spatially-controlled piezoelectric neural stimulation via low-intensity focused ultrasound
Han, M., Yildiz, E., Bozuyuk, U., Aydin, A., Yu, Y., Bhargava, A., Karaz, S., Sitti, M.
Nature Communications, 15(1):2013, 2024 (article)
Electrical stimulation is a fundamental tool in studying neural circuits, treating neurological diseases, and advancing regenerative medicine. Injectable, free-standing piezoelectric particle systems have emerged as non-genetic and wireless alternatives for electrode-based tethered stimulation systems. However, achieving cell-specific and high-frequency piezoelectric neural stimulation remains challenging due to high-intensity thresholds, non-specific diffusion, and internalization of particles. Here, we develop cell-sized 20 μm-diameter silica-based piezoelectric magnetic Janus microparticles (PEMPs), enabling clinically-relevant high-frequency neural stimulation of primary neurons under low-intensity focused ultrasound. Owing to its functionally anisotropic design, half of the PEMP acts as a piezoelectric electrode via conjugated barium titanate nanoparticles to induce electrical stimulation, while the nickel-gold nanofilm-coated magnetic half provides spatial and orientational control on neural stimulation via external uniform rotating magnetic fields. Furthermore, surface functionalization with targeting antibodies enables cell-specific binding/targeting and stimulation of dopaminergic neurons. Taking advantage of such functionalities, the PEMP design offers unique features towards wireless neural stimulation for minimally invasive treatment of neurological diseases.
Roadmap for Clinical Translation of Mobile Microrobotics
Bozuyuk, U., Wrede, P., Yildiz, E., Sitti, M.
Advanced Materials, 2311462, 2024 (article)
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.
2023
Swarming magnetic surface microrollers enable directed locomotion in circular confinements
Research Square, July 2023 (article)
Electrodeposited Superhydrophilic-Superhydrophobic Composites for Untethered Multi-Stimuli-Responsive Soft Millirobots
Zheng, Z., Han, J., Demir, S. O., Wang, H., Jiang, W., Liu, H., Sitti, M.
Advanced Science, pages: 2302409, June 2023 (article)
Pangolin-inspired untethered magnetic robot for on-demand biomedical heating applications
Soon, R. H., Yin, Z., Dogan, M. A., Dogan, N. O., Tiryaki, M. E., Karacakol, A. C., Aydin, A., Esmaeili-Dokht, P., Sitti, M.
Nature Communications, 14(1):3320, June 2023 (article)
Microrobotic Locomotion in Blood Vessels: A Computational Study on the Performance of Surface Microrollers in the Cardiovascular System
Advanced Intelligent Systems, pages: 2300099, June 2023 (article)
The mismatch between experimental and computational fluid dynamics analyses for magnetic surface microrollers
Bozuyuk, U., Ozturk, H., Sitti, M.
Scientific Reports, 13(1):10196, June 2023 (article)
A Versatile Jellyfish-Like Robotic Platform for Effective Underwater Propulsion and Manipulation
Wang, T., Joo, H., Song, S., Hu, W., Keplinger, C., Sitti, M.
Science Advances, 9(15), American Association for the Advancement of Science, April 2023, Tianlu Wang and Hyeong-Joon Joo contributed equally to this work. (article)
Underwater devices are critical for environmental applications. However, existing prototypes typically use bulky, noisy actuators and limited configurations. Consequently, they struggle to ensure noise-free and gentle interactions with underwater species when realizing practical functions. Therefore, we developed a jellyfish-like robotic platform enabled by a synergy of electrohydraulic actuators and a hybrid structure of rigid and soft components. Our 16-cm-diameter noise-free prototype could control the fluid flow to propel while manipulating objects to be kept beneath its body without physical contact, thereby enabling safer interactions. Its against-gravity speed was up to 6.1 cm/s, substantially quicker than other examples in literature, while only requiring a low input power of around 100 mW. Moreover, using the platform, we demonstrated contact-based object manipulation, fluidic mixing, shape adaptation, steering, wireless swimming, and cooperation of two to three robots. This study introduces a versatile jellyfish-like robotic platform with a wide range of functions for diverse applications.
MRI-powered Magnetic Miniature Capsule Robot with HIFU-controlled On-demand Drug Delivery
Tiryaki, M. E., Dogangun, F., Dayan, C. B., Wrede, P., Sitti, M.
arXiv preprint arXiv:2301.07197, 2023 (article)
Magnetic guidewire steering at ultrahigh magnetic fields
Tiryaki, M. E., Elmacıoğlu, Y. G., Sitti, M.
Science Advances, 9(17):eadg6438, 2023 (article)
Deployable Soft Origami Modular Robotic Arm With Variable Stiffness Using Facet Buckling
Park, M., Kim, W., Yu, S., Cho, J., Kang, W., Byun, J., Jeong, U., Cho, K.
IEEE Robotics and Automation Letters, 8(2):864-871, 2023 (article)
Acoustic Trapping and Manipulation of Hollow Microparticles under Fluid Flow Using a Single-Lens Focused Ultrasound Transducer
Wrede, P., Aghakhani, A., Bozuyuk, U., Yildiz, E., Sitti, M.
ACS Applied Materials \& Interfaces, 15(45):52224-52236, 2023 (article)
Carrier, use of a carrier, method of activating a carrier and method of making a carrier
2023, US Patent App. 16/500,442 (patent)
A ferroelectric/ferroelastic energy harvester: Load impedance and frequency effects
Kang, W., Cain, C., Paynter, R., Huber, J. E.
Energy Conversion and Management, 277, pages: 116687, 2023 (article)
Machine Learning-Based Shear Optimal Adhesive Microstructures with Experimental Validation
Dayan, C. B., Son, D., Aghakhani, A., Wu, Y., Demir, S. O., Sitti, M.
Small, pages: 2304437, 2023 (article)
Designing Covalent Organic Framework-based Light-driven Microswimmers towards Intraocular Theranostic Applications
Sridhar, V., Yildiz, E., Rodrı́guez-Camargo, A., Lyu, X., Yao, L., Wrede, P., Aghakhani, A., Akolpoglu, M. B., Podjaski, F., Lotsch, B. V., Sitti, M.
Advanced Materials, 35, pages: 2301126, 2023 (article)
While micromachines with tailored functionalities enable therapeutic applications in biological environments, their controlled motion and targeted drug delivery in biological media require sophisticated designs for practical applications. Covalent organic frameworks (COFs), a new generation of crystalline and nanoporous polymers, offer new perspectives for light-driven microswimmers in heterogeneous biological environments including intraocular fluids, thus setting the stage for biomedical applications such as retinal drug delivery. Two different types of COFs, uniformly spherical TABP-PDA-COF sub-micrometer particles and texturally nanoporous, micrometer-sized TpAzo-COF particles are described and compared as light-driven microrobots. They can be used as highly efficient visible-light-driven drug carriers in aqueous ionic and cellular media. Their absorption ranging down to red light enables phototaxis even in deeper and viscous biological media, while the organic nature of COFs ensures their biocompatibility. Their inherently porous structures with ≈2.6 and ≈3.4 nm pores, and large surface areas allow for targeted and efficient drug loading even for insoluble drugs, which can be released on demand. Additionally, indocyanine green (ICG) dye loading in the pores enables photoacoustic imaging, optical coherence tomography, and hyperthermia in operando conditions. This real-time visualization of the drug-loaded COF microswimmers enables unique insights into the action of photoactive porous drug carriers for therapeutic applications.
Avian-Inspired Perching Mechanism for Jumping Robots
Advanced Intelligent Systems, pages: 2300072, 2023 (article)
Broad-Wavelength Light-Driven High-Speed Hybrid Crystal Actuators Actuated Inside Tissue-Like Phantoms
Kim, D. W., Hagiwara, Y., Hasebe, S., Dogan, N. O., Zhang, M., Asahi, T., Koshima, H., Sitti, M.
Advanced Functional Materials, 33(47):2305916, 2023 (article)
Microrobotic Locomotion in Blood Vessels: A Computational Study on the Performance of Surface Microrollers in the Cardiovascular System
Advanced Intelligent Systems, 5(9):2300099, 2023 (article)
Hygroscopic Materials
Guo, S., De Wolf, S., Sitti, M., Serre, C., Tan, S. C.
Advanced Materials, 36(12):2311445, 2023 (article)
Active Tail Configurations for Enhanced Body Reorientation Performance
Advanced Intelligent Systems, 5(2):2200219, 2023 (article)
Microfibers with mushroom-shaped tips for optimal adhesion
Sitti, M., Aksak, B.
2023, US Patent 11,613,674 (patent)
Acoustic Streaming-Induced Multimodal Locomotion of Bubble-Based Microrobots
Mahkam, N., Aghakhani, A., Sheehan, D., Gardi, G., Katzschmann, R., Sitti, M.
Advanced Science, 10(35):2304233, 2023 (article)
Size-Dependent Locomotion Ability of Surface Microrollers on Physiologically Relevant Microtopographical Surfaces
Small, 19(47):2303396, 2023 (article)
Magnetic trap system and method of navigating a microscopic device
Son, D., Ugurlu, M., Bluemer, P., Sitti, M.
2023, US Patent App. 17/871,598 (patent)
A Liquid Repellent Fibrillar Dry Adhesive Material and a Method of Producing the Same
2023, US Patent App. 17/785,452 (patent)