{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,21]],"date-time":"2026-02-21T18:53:33Z","timestamp":1771700013456,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2020,5,15]],"date-time":"2020-05-15T00:00:00Z","timestamp":1589500800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The next generation of intelligent robotic systems has been envisioned as micro-scale mobile and externally controllable robots. Visualization of such small size microrobots to track their motion in nontransparent medium such as human tissue remains a major challenge, limiting translation into clinical applications. Herein, we present a novel, non-invasive, real-time imaging method by integrating ultrasound (US) and photoacoustic (PA) imaging modalities for tracking and detecting the motion of a single microrobot in deep biological tissue. We developed and evaluated a prototyped PA-guided magnetic microrobot tracking system. The microrobots are fabricated using photoresist mixed with nickel (Ni) particles. The microrobot motion was controlled using an externally applied magnetic field. Our experimental results evaluated the capabilities of PA imaging in visualizing and tracking microrobots in opaque tissue and tissue-mimicking phantoms. The results also demonstrate the ability of PA imaging in detecting a microrobot with the sizes less than the minimum detectable size by US imaging (down to 50 \u00b5m). The spectroscopic PA imaging studies determined an optimal wavelength (700 nm) for imaging microrobots with embedded Ni particles in oxygenated (fresh) human blood. In addition, we examined the ability of PA imaging to detect the microrobots through a nontransparent tissue mimic and at a depth of 25 mm, where conventional optical methods are unable to be used in tracking the objects. These initial results demonstrate the feasibility of an integrated US and PA imaging method to push the boundaries of microrobot applications into translational applications.<\/jats:p>","DOI":"10.3390\/s20102816","type":"journal-article","created":{"date-parts":[[2020,5,15]],"date-time":"2020-05-15T10:53:59Z","timestamp":1589540039000},"page":"2816","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Photoacoustic Imaging to Track Magnetic-manipulated Micro-Robots in Deep Tissue"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8137-2372","authenticated-orcid":false,"given":"Yan","family":"Yan","sequence":"first","affiliation":[{"name":"Department of Biomedical Engineering, Wayne State University, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wuming","family":"Jing","sequence":"additional","affiliation":[{"name":"A. Linton Department of Mechanical Engineering, Lawrence Technological University, Southfield, MI 48075, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mohammad","family":"Mehrmohammadi","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Wayne State University, Detroit, MI 48201, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,5,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1038\/s41578-018-0016-9","article-title":"Bioinspired microrobots","volume":"3","author":"Palagi","year":"2018","journal-title":"Nat. Rev. Mater."},{"key":"ref_2","first-page":"405","article-title":"Magnetically powered microrobots: A medical revolution underway?","volume":"51","author":"Chautems","year":"2017","journal-title":"Eur. J. Cardio-Thorac. Surg."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1109\/JPROC.2014.2385105","article-title":"Biomedical Applications of Untethered Mobile Milli\/Microrobots","volume":"103","author":"Sitti","year":"2015","journal-title":"Proc. IEEE"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Wang, Q., Yang, L., Yu, J., Vong, C.-I., Chiu, P.W.Y., and Zhang, L. (2018, January 1\u20135). Magnetic Navigation of a Rotating Colloidal Swarm Using Ultrasound Images. Proceedings of the 2018 IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS), Madrid, Spain.","DOI":"10.1109\/IROS.2018.8593898"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"150","DOI":"10.5772\/58985","article-title":"Towards mobile microrobot swarms for additive micromanufacturing","volume":"11","author":"Cappelleri","year":"2014","journal-title":"Int. J. Adv. Robot. Syst."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"eaav4494","DOI":"10.1126\/scirobotics.aav4494","article-title":"Millimeter-scale flexible robots with programmable three-dimensional magnetization and motions","volume":"4","author":"Xu","year":"2019","journal-title":"Sci. Robot."},{"key":"ref_7","unstructured":"Szabo, T.L. (2004). Diagnostic Ultrasound Imaging: Inside Out, Academic Press."},{"key":"ref_8","unstructured":"Edelman, S.K. (2003). Understanding Ultrasound Physics, Baker & Taylor."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"S\u00e1nchez, A., Magdanz, V., Schmidt, O.G., and Misra, S. (2014, January 12\u201315). Magnetic control of self-propelled microjets under ultrasound image guidance. Proceedings of the 5th IEEE RAS\/EMBS International Conference on Biomedical Robotics and Biomechatronics, Sao Paulo, Brazil.","DOI":"10.1109\/BIOROB.2014.6913771"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1458","DOI":"10.1126\/science.1216210","article-title":"Photoacoustic tomography: In vivo imaging from organelles to organs","volume":"335","author":"Wang","year":"2012","journal-title":"Science"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"041101","DOI":"10.1063\/1.2195024","article-title":"Photoacoustic imaging in biomedicine","volume":"77","author":"Xu","year":"2006","journal-title":"Rev. Sci. Instrum."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"89","DOI":"10.2174\/2211555211302010010","article-title":"Photoacoustic imaging for cancer detection and staging","volume":"2","author":"Mehrmohammadi","year":"2013","journal-title":"Curr. Mol. Imaging"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"4643","DOI":"10.1364\/BOE.10.004643","article-title":"Photoacoustic imaging of the uterine cervix to assess collagen and water content changes in murine pregnancy","volume":"10","author":"Yan","year":"2019","journal-title":"Biomed. Opt. Express"},{"key":"ref_14","first-page":"046004","article-title":"All-reflective ring illumination system for photoacoustic tomography","volume":"24","author":"Alshahrani","year":"2019","journal-title":"J. Biomed. Opt."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"100139","DOI":"10.1016\/j.pacs.2019.100139","article-title":"Miniaturized phased-array ultrasound and photoacoustic endoscopic imaging system","volume":"15","author":"Basij","year":"2019","journal-title":"Photoacoustics"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1002\/uog.20649","article-title":"OP01. 03: Development of an endocavity ultrasound and photoacoustic imaging device for non-invasive assessment of blood oxygenation and perfusion in fetuses and neonates","volume":"54","author":"Mehrmohammadi","year":"2019","journal-title":"Ultrasound Obstet. Gynecol."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Alijabbari, N., Alshahrani, S.S., Pattyn, A., and Mehrmohammadi, M. (2019). Photoacoustic Tomography with a Ring Ultrasound Transducer: A Comparison of Different Illumination Strategies. Appl. Sci., 9.","DOI":"10.3390\/app9153094"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Yan, Y., Basij, M., Wang, Z., Siddiqui, A., Dong, J., Alijabbari, N., Hernandez-Andrade, E., Gomez-Lopez, N., Hassan, S., and Mehrmohammadi, M. (2018, January 22\u201325). Multi-parametric acoustic imaging of cervix for more accurate detection of patients at risk of preterm birth. Proceedings of the 2018 IEEE International Ultrasonics Symposium (IUS), Kobe, Japan.","DOI":"10.1109\/ULTSYM.2018.8580030"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Basij, M., Yan, Y., Alshahrani, S., Winer, I., Burmeister, J., Dominello, M., and Mehrmohammadi, M. (2018, January 22\u201325). Development of an Ultrasound and Photoacoustic Endoscopy System for Imaging of Gynecological Disorders. Proceedings of the 2018 IEEE International Ultrasonics Symposium (IUS), Kobe, Japan.","DOI":"10.1109\/ULTSYM.2018.8579788"},{"key":"ref_20","unstructured":"Mehrmohammadi, M., Hernandez-Andrade, E., Gelovani, J.G., Hassan, S.S., and Yan, Y. (2018). Ultrasound and Photoacoustic Systems and Methods for Fetal Brain Assessment During Delivery. (US 2018 \/ 0214119 A1), Google Patents."},{"key":"ref_21","unstructured":"Basij, M., Yan, Y., Alshahrani, S.S., Sau, S., Iyer, A., Seward, S.S., Burmeister, J.W., Dominello, M., and Mehrmohammadi, M. (2018, January 13\u201315). Combined phased-array ultrasound and photoacoustic endoscope for gynecologic cancer imaging applications. Proceedings of the Medical Imaging 2018: Ultrasonic Imaging and Tomography, Houston, TX, USA."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1063\/1.3141939","article-title":"Photoacoustics for molecular imaging and therapy","volume":"62","author":"Emelianov","year":"2009","journal-title":"Phys. Today"},{"key":"ref_23","first-page":"404","article-title":"Upon the production and reproduction of sound by light","volume":"9","author":"Bell","year":"1880","journal-title":"J. Soc. Telegr. Eng."},{"key":"ref_24","first-page":"1","article-title":"Photoacoustic-based visual servoing of a needle tip","volume":"8","author":"Bell","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2243","DOI":"10.1364\/BOE.2.002243","article-title":"Photoacoustic imaging of prostate brachytherapy seeds","volume":"2","author":"Su","year":"2011","journal-title":"Biomed. Opt. Express"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"eaax0613","DOI":"10.1126\/scirobotics.aax0613","article-title":"A microrobotic system guided by photoacoustic computed tomography for targeted navigation in intestines in vivo","volume":"4","author":"Wu","year":"2019","journal-title":"Sci. Robot."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Kim, S., Chen, Y.-S., Luke, G.P., Mehrmohammadi, M., Cook, J.R., and Emelianov, S.Y. (2010, January 11\u201314). Ultrasound and photoacoustic image-guided photothermal therapy using silica-coated gold nanorods: In-vivo study. Proceedings of the 2010 IEEE International Ultrasonics Symposium, San Diego, CA, USA.","DOI":"10.1109\/ULTSYM.2010.5935601"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1021\/nl1042006","article-title":"Silica-coated gold nanorods as photoacoustic signal nanoamplifiers","volume":"11","author":"Chen","year":"2011","journal-title":"Nano Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"312","DOI":"10.1364\/BOE.7.000312","article-title":"High frame rate photoacoustic imaging at 7000 frames per second using clinical ultrasound system","volume":"7","author":"Sivasubramanian","year":"2016","journal-title":"Biomed. Opt. Express"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"John, S., Yan, Y., Forta, S.Y., Kabbani, L., and Mehrmohammadi, M. (2019, January 6\u20139). Integrated Ultrasound and Photoacoustic Imaging for Effective Endovenous Laser Ablation: A Characterization Study. Proceedings of the 2019 IEEE International Ultrasonics Symposium (IUS), Glasgow, UK.","DOI":"10.1109\/ULTSYM.2019.8925790"},{"key":"ref_31","unstructured":"Prahl, S. (2020, April 28). Optical Absorption of Hemoglobin. Available online: http:\/\/omlc. ogi. edu\/spectra\/hemoglobin."},{"key":"ref_32","first-page":"3","article-title":"Simultaneous determination of iron, copper, chrome, nickel by multi-wavelength spectrophotometry","volume":"6","author":"Xiong","year":"2013","journal-title":"Nonferrous Met. Sci. Eng."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/10\/2816\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T09:29:08Z","timestamp":1760174948000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/10\/2816"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,5,15]]},"references-count":32,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2020,5]]}},"alternative-id":["s20102816"],"URL":"https:\/\/doi.org\/10.3390\/s20102816","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,5,15]]}}}