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Magnetic imaging of a single ferromagnetic nanowire using diamond atomic sensors
Lee, Myeongwon,Jang, Bumjin,Yoon, Jungbae,Mathpal, Mohan C,Lee, Yuhan,Kim, Chulki,Pane, Salvador,Nelson, Bradley J,Lee, Donghun IOP 2018 Nanotechnology Vol.29 No.40
<P>Recent advances in nanorobotic manipulation of ferromagnetic nanowires bring new avenues for applications in the biomedical area, such as targeted drug delivery, diagnostics or localized surgery. However, probing a single nanowire and monitoring its dynamics remains a challenge since it demands high precision sensing, high-resolution imaging, and stable operations in fluidic environments. Here, we report on a novel method of imaging and sensing magnetic fields from a single ferromagnetic nanowire with an atomic-scale sensor in diamond, i.e. diamond nitrogen-vacancy (NV) defect center. The distribution of static magnetic fields around a single Co nanowire is mapped out by spatially distributed NV centers and the obtained image is further compared with numerical simulation for quantitative analysis. DC field measurements such as continuous-wave ODMR and Ramsey sequence are used in the paper and sub Gauss level of field sensing is demonstrated. By imaging magnetic fields at a single nanowire level, this work represents an important step toward tracking and probing of ferromagnetic nanowires in biomedical applications.</P>
Jeon, Sungwoong,Hoshiar, Ali Kafash,Kim, Kangho,Lee, Seungmin,Kim, Eunhee,Lee, Sunkey,Kim, Jin-young,Nelson, Bradley J.,Cha, Hyo-Jeong,Yi, Byung-Ju,Choi, Hongsoo Mary Ann Liebert, Inc., publishers 2018 Soft robotics Vol.2018 No.-
<P><B>Abstract</B></P><P>Magnetically actuated soft robots may improve the treatment of disseminated intravascular coagulation. Significant progress has been made in the development of soft robotic systems that steer catheters. A more challenging task, however, is the development of systems that steer sub-millimeter-diameter guidewires during intravascular treatments; a novel microrobotic approach is required for steering. In this article, we develop a novel, magnetically actuated, soft microrobotic system, increasing the steerability of a conventional guidewire. The soft microrobot is attached to the tip of the guidewire, and it is magnetically steered by changing the direction and intensity of an external magnetic field. The microrobot is fabricated via replica molding and features a soft body made of polydimethylsiloxane, two permanent magnets, and a microspring. We developed a mathematical model mapping deformation of the soft microrobot using a feed-forward approach toward steering. Then, we used the model to steer a guidewire. The angulation of the microrobot can be controlled from 21.1° to 132.7° by using a magnetic field of an intensity of 15 mT. Steerability was confirmed by two-dimensional <I>in vitro</I> tracking. Finally, a guidewire with the soft microrobot was tested by using a three-dimensional (3D) phantom of the coronary artery to verify steerability in 3D space.</P>