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Publication Open Access 3D microprinting of iron platinum nanoparticle-based magnetic mobile microrobots(Wiley, 2021) Giltinan, Joshua; Sridhar, Varun; Bozüyük, Uğur; Sheehan, Devin; Department of Mechanical Engineering; Sitti, Metin; Faculty Member; Department of Mechanical Engineering; School of Medicine; College of Engineering; 297104Wireless magnetic microrobots are envisioned to revolutionize minimally invasive medicine. While many promising medical magnetic microrobots are proposed, the ones using hard magnetic materials are not mostly biocompatible, and the ones using biocompatible soft magnetic nanoparticles are magnetically very weak and, therefore, difficult to actuate. Thus, biocompatible hard magnetic micro/nanomaterials are essential toward easy-to-actuate and clinically viable 3D medical microrobots. To fill such crucial gap, this study proposes ferromagnetic and biocompatible iron platinum (FePt) nanoparticle-based 3D microprinting of microrobots using the two-photon polymerization technique. A modified one-pot synthesis method is presented for producing FePt nanoparticles in large volumes and 3D printing of helical microswimmers made from biocompatible trimethylolpropane ethoxylate triacrylate (PETA) polymer with embedded FePt nanoparticles. The 30 mu m long helical magnetic microswimmers are able to swim at speeds of over five body lengths per second at 200Hz, making them the fastest helical swimmer in the tens of micrometer length scale at the corresponding low-magnitude actuation fields of 5-10mT. It is also experimentally in vitro verified that the synthesized FePt nanoparticles are biocompatible. Thus, such 3D-printed microrobots are biocompatible and easy to actuate toward creating clinically viable future medical microrobots.
Publication Metadata only BirdBot achieves energy-efficient gait with minimal control using avian-inspired leg clutching(American Association for the Advancement of Science (AAAS), 2022) Badri-Sprowitz, Alexander; Sarvestani, Alborz Aghamaleki; Daley, Monica A.; N/A; Department of Mechanical Engineering; Sitti, Metin; Faculty Member; Department of Mechanical Engineering; School of Medicine; College of Engineering; 297104Designers of legged robots are challenged with creating mechanisms that allow energy-efficient locomotion with robust and minimalistic control. Sources of high energy costs in legged robots include the rapid loading and high forces required to support the robot's mass during stance and the rapid cycling of the leg's state between stance and swing phases. Here, we demonstrate an avian-inspired robot leg design, BirdBot, that challenges the reliance on rapid feedback control for joint coordination and replaces active control with intrinsic, mechanical coupling, reminiscent of a self-engaging and disengaging clutch. A spring tendon network rapidly switches the leg's slack segments into a loadable state at touchdown, distributes load among joints, enables rapid disengagement at toe-off through elastically stored energy, and coordinates swing leg flexion. A bistable joint mediates the spring tendon network's disengagement at the end of stance, powered by stance phase leg angle progression. We show reduced knee-flexing torque to a 10th of what is required for a nonclutching, parallel-elastic leg design with the same kinematics, whereas spring-based compliance extends the leg in stance phase. These mechanisms enable bipedal locomotion with four robot actuators under feedforward control, with high energy efficiency. The robot offers a physical model demonstration of an avian-inspired, multiarticular elastic coupling mechanism that can achieve self-stable, robust, and economic legged locomotion with simple control and no sensory feedback. The proposed design is scalable, allowing the design of large legged robots. BirdBot demonstrates a mechanism for self-engaging and disengaging parallel elastic legs that are contact-triggered by the foot's own lever-arm action.Publication Open Access Children's reliance on the non-verbal cues of a robot versus a human(Public Library of Science, 2019) Verhagen J.; Van Den Berghe R.; Oudgenoeg-Paz O.; Leseman P.; Department of Psychology; Küntay, Aylin C.; Faculty Member; Department of Psychology; College of Social Sciences and Humanities; 178879Robots are used for language tutoring increasingly often, and commonly programmed to display non-verbal communicative cues such as eye gaze and pointing during robot-child interactions. With a human speaker, children rely more strongly on non-verbal cues (pointing) than on verbal cues (labeling) if these cues are in conflict. However, we do not know how children weigh the non-verbal cues of a robot. Here, we assessed whether four- to six-year-old children (i) differed in their weighing of non-verbal cues (pointing, eye gaze) and verbal cues provided by a robot versus a human; (ii) weighed non-verbal cues differently depending on whether these contrasted with a novel or familiar label; and (iii) relied differently on a robot's non-verbal cues depending on the degree to which they attributed human-like properties to the robot. The results showed that children generally followed pointing over labeling, in line with earlier research. Children did not rely more strongly on the non-verbal cues of a robot versus those of a human. Regarding pointing, children who perceived the robot as more human-like relied on pointing more strongly when it contrasted with a novel label versus a familiar label, but children who perceived the robot as less human-like did not show this difference. Regarding eye gaze, children relied more strongly on the gaze cue when it contrasted with a novel versus a familiar label, and no effect of anthropomorphism was found. Taken together, these results show no difference in the degree to which children rely on non-verbal cues of a robot versus those of a human and provide preliminary evidence that differences in anthropomorphism may interact with children's reliance on a robot's non-verbal behaviors.Publication Metadata only Effect of Al2O3 and ZrO2 filler material on the microstructural, thermal and dielectric properties of borosilicate glass-ceramics(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Karaahmet, Oğuz; Çiçek, Buğra; N/A; Department of Chemistry; Arıbuğa, Dilara; Balcı, Özge; PhD Student; Researcher; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 295531Various glass-ceramics are widely used or considered for use as components of microelectronic materials due to their promising properties. In this study, borosilicate glass was prepared using the powder metallurgical route and then mixed with different amounts of Al2O3 and ZrO2 filler materials. Glass-ceramics are produced by high-energy ball milling and conventional sintering process under Ar or air. In this study, the effects of different filler materials and different atmospheres on the microstructural, thermal and dielectric properties were investigated. The data showed that ZrO2 filler material led to better results than Al2O3 under identical working conditions and similar composite structures. ZrO2 filler material significantly enhanced the densification process of glass-ceramics (100% relative density) and led to a thermal conductivity of 2.904 W/K.m, a dielectric constant of 3.97 (at 5 MHz) and a dielectric loss of 0.0340 (at 5 MHz) for the glass with 30 wt.% ZrO2 sample. This paper suggests that prepared borosilicate glass-ceramics have strong sinterability, high thermal conductivity, and low dielectric constants, making them promising candidates for microelectronic devices.Publication Metadata only Elucidating the interaction dynamics between microswimmer body and immune system for medical microrobots(Amer Assoc Advancement Science, 2020) Yasa, Immihan Ceren; Ceylan, Hakan; Bozuyuk, Ugur; Wild, Anna-Maria; N/A; Department of Mechanical Engineering; Sitti, Metin; Faculty Member; Department of Mechanical Engineering; School of Medicine; College of Engineering; 297104The structural design parameters of a medical microrobot, such as the morphology and surface chemistry, should aim to minimize any physical interactions with the cells of the immune system. However, the same surface-borne design parameters are also critical for the locomotion performance of the microrobots. Understanding the interplay of such parameters targeting high locomotion performance and low immunogenicity at the same time is of paramount importance yet has so far been overlooked. Here, we investigated the interactions of magnetically steerable double-helical microswimmers with mouse macrophage cell lines and splenocytes, freshly harvested from mouse spleens, by systematically changing their helical morphology. We found that the macrophages and splenocytes can recognize and differentially elicit an immune response to helix turn numbers of the microswimmers that otherwise have the same size, bulk physical properties, and surface chemistries. Our findings suggest that the structural optimization of medical microrobots for the locomotion performance and interactions with the immune cells should be considered simultaneously because they are highly entangled and can demand a substantial design compromise from one another. Furthermore, we show that morphology-dependent interactions between macrophages and microswimmers can further present engineering opportunities for biohybrid microrobot designs. We demonstrate immunobots that can combine the steerable mobility of synthetic microswimmers and the immunoregulatory capability of macrophages for potential targeted immunotherapeutic applications.Publication Open Access Envisioning social drones in education(Frontiers, 2022) Johal, W.; Obaid, M.; Department of Media and Visual Arts; N/A; Yantaç, Asım Evren; Gatos, Doğa Çorlu; Faculty Member; Department of Media and Visual Arts; College of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; 52621; N/AEducation is one of the major application fields in social Human-Robot Interaction. Several forms of social robots have been explored to engage and assist students in the classroom environment, from full-bodied humanoid robots to tabletop robot companions, but flying robots have been left unexplored in this context. In this paper, we present seven online remote workshops conducted with 20 participants to investigate the application area of Education in the Human-Drone Interaction domain; particularly focusing on what roles a social drone could fulfill in a classroom, how it would interact with students, teachers and its environment, what it could look like, and what would specifically differ from other types of social robots used in education. In the workshops we used online collaboration tools, supported by a sketch artist, to help envision a social drone in a classroom. The results revealed several design implications for the roles and capabilities of a social drone, in addition to promising research directions for the development and design in the novel area of drones in education.Publication Metadata only Guidelines for designing social robots as second language tutors(Springer, 2018) Belpaeme, Tony; Vogt, Paul; van den Berghe, Rianne; Bergmann, Kirsten; de Haas, Mirjam; Kennedy, James; Oudgenoeg-Paz, Ora; Papadopoulos, Fotios; Schodde, Thorsten; Verhagen, Josje; Wallbridge, Christopher D.; Willemsen, Bram; de Wit, Jan; Hoffmann, Laura; Kopp, Stefan; Krahmer, Emiel; Montanier, Jean-Marc; Pandey, Amit Kumar; Department of Psychology; Department of Psychology; Department of Psychology; Department of Psychology; Department of Psychology; Department of Psychology; Göksun, Tilbe; Kanero, Junko; Küntay, Aylin C.; Geçkin, Vasfiye; Mamuş, Ayşe Ezgi; Oranç, Cansu; Faculty Member; Researcher; Faculty Member; Researcher; Researcher; Researcher; Department of Psychology; College of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; 47278; N/A; 178879; N/A; N/A; N/AIn recent years, it has been suggested that social robots have potential as tutors and educators for both children and adults. While robots have been shown to be effective in teaching knowledge and skill-based topics, we wish to explore how social robots can be used to tutor a second language to young children. As language learning relies on situated, grounded and social learning, in which interaction and repeated practice are central, social robots hold promise as educational tools for supporting second language learning. This paper surveys the developmental psychology of second language learning and suggests an agenda to study how core concepts of second language learning can be taught by a social robot. It suggests guidelines for designing robot tutors based on observations of second language learning in human-human scenarios, various technical aspects and early studies regarding the effectiveness of social robots as second language tutors.Publication Metadata only Light-driven carbon nitride microswimmers with propulsion in biological and ionic media and responsive on-demand drug delivery(American Association for the Advancement of Science (AAAS), 2022) Sridhar, Varun; Podjaski, Filip; Alapan, Yunus; Kroeger, Julia; Grunenberg, Lars; Kishore, Vimal; Lotsch, Bettina, V; N/A; Department of Mechanical Engineering; Sitti, Metin; Faculty Member; Department of Mechanical Engineering; School of Medicine; College of Engineering; 297104We propose two-dimensional poly(heptazine imide) (PHI) carbon nitride microparticles as light-driven microswimmers in various ionic and biological media. Their high-speed (15 to 23 micrometer per second; 9.5 +/- 5.4 body lengths per second) swimming in multicomponent ionic solutions with concentrations up to 5 M and without dedicated fuels is demonstrated, overcoming one of the bottlenecks of previous light-driven microswimmers. Such high ion tolerance is attributed to a favorable interplay between the particle's textural and structural nano porosity and optoionic properties, facilitating ionic interactions in solutions with high salinity. Biocompatibility of these microswimmers is validated by cell viability tests with three different cell lines and primary cells. The nanopores of the swimmers are loaded with a model cancer drug, doxorubicin (DOX), resulting in a high (185%) loading efficiency without passive release. Controlled drug release is reported under different pH conditions and can be triggered on-demand by illumination. Light-triggered, boosted release of DOX and its active degradation products are demonstrated under oxygen-poor conditions using the intrinsic, environmentally sensitive and light-induced charge storage properties of PHI, which could enable future theranostic applications in oxygen deprived tumor regions. These organic PHI microswimmers simultaneously address the current light-driven microswimmer challenges of high ion tolerance, fuel-free high-speed propulsion in biological media, biocompatibility, and controlled on-demand cargo release toward their biomedical, environmental, and other potential applications.Publication Metadata only Magnetically actuated gearbox for the wireless control of millimeter-scale robots(American Association for the Advancement of Science (AAAS), 2022) Hong, Chong; Ren, Ziyu; Wang, Che; Li, Mingtong; Wu, Yingdan; Tang, Dewei; Hu, Wenqi; N/A; Department of Mechanical Engineering; Sitti, Metin; Faculty Member; Department of Mechanical Engineering; School of Medicine; College of Engineering; 297104The limited force or torque outputs of miniature magnetic actuators constrain the locomotion performances and functionalities of magnetic millimeter-scale robots. Here, we present a magnetically actuated gearbox with a maximum size of 3 millimeters for driving wireless millirobots. The gearbox is assembled using microgears that have reference diameters down to 270 micrometers and are made of aluminum-filled epoxy resins through casting. With a magnetic disk attached to the input shaft, the gearbox can be driven by a rotating external magnetic field, which is not more than 6.8 millitesla, to produce torque of up to 0.182 millinewton meters at 40 hertz. The corresponding torque and power densities are 12.15 micronewton meters per cubic millimeter and 8.93 microwatt per cubic millimeter, respectively. The transmission efficiency of the gearbox in the air is between 25.1 and 29.2% at actuation frequencies ranging from 1 to 40 hertz, and it lowers when the gearbox is actuated in viscous liquids. This miniature gearbox can be accessed wirelessly and integrated with various functional modules to repeatedly generate large actuation forces, strains, and speeds; store energy in elastic components; and lock up mechanical linkages. These characteristics enable us to achieve a peristaltic robot that can crawl on a flat substrate or inside a tube, a jumping robot with a tunable jumping height, a clamping robot that can sample solid objects by grasping, a needle-puncture robot that can take samples from the inside of the target, and a syringe robot that can collect or release liquids.Publication Metadata only Magnetically actuated soft capsule endoscope for fine-needle biopsy(Mary Ann Liebert, Inc, 2020) Son, Donghoon; Gilbert, Hunter; N/A; Department of Mechanical Engineering; Sitti, Metin; Faculty Member; Department of Mechanical Engineering; School of Medicine; College of Engineering; 297104Wireless capsule endoscopes have revolutionized diagnostic procedures in the gastrointestinal (GI) tract by minimizing discomfort and trauma. Biopsy procedures, which are often necessary for a confirmed diagnosis of an illness, have been incorporated recently into robotic capsule endoscopes to improve their diagnostic functionality beyond only imaging. However, capsule robots to date have only been able to acquire biopsy samples of superficial tissues of the GI tract, which could generate false-negative diagnostic results if the diseased tissue is under the surface of the GI tract. To improve their diagnostic accuracy for submucosal tumors/diseases, we propose a magnetically actuated soft robotic capsule robot, which takes biopsy samples in a deep tissue of a stomach using the fine-needle biopsy technique. We present the design, control, and human-machine interfacing methods for the fine-needle biopsy capsule robot. Ex vivo experiments in a porcine stomach show 85% yield for the biopsy of phantom tumors located underneath the first layers of the stomach wall.