NON-INVASIVE TRACKING OF MICRO-SCALE MICROROBOT USING PHOTOACOUSTIC IMAGING

This paper presents the innovative integration of both frontier submillimeter magnetic microrobot and integrated ultrasound and photoacoustic (USPA) imaging. The integrative technique will allow for potential real non-invasive microrobot operation in deep biological tissue for biomedical applications. In this study, the magnetic microrobot prototypes are fabricated in series of different sizes through patterning SU-8 photoresist mixed with nickel particles. In order for proof-of-concept, the magnetic microrobot is actuated by a static magnetic field, which is produced by a multiple magnet cone array. As mimicking the opaque biological environment, the magnetic microrobot is placed in a fluid environment bounded by a non-transparent phantom. The USPA imaging system consists of a laser system to illuminate working space and an ultrasound system to receive the acoustic signal generated by imaging object due to photonic signal absorption. The experimental tests prove that the USPA imaging protocol can detect single microrobot smaller than 100 mu m through the 15 mm thick opaque phantom. The imaging test has been accomplished both statically and in a motion of approximately 2.0 mm/s. Further investigation of this concept will focus on the collaboration of photoacoustic imaging and magnetic manipulation of microrobot under real biological fluid media.