Poster Y13 - Magnetoacoustic micromotors for cell manipulation

Saturday, October 26, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Co-Author(s)

FK

Fatma Ceren Kirmizitas

Graduate Student
University of Delaware, United States
Max Sokolich, BS

Graduate Student
University of Delaware, United States

Presenting Author(s)

SAMBEETA sambeeta, PhD

Assistant Professor
University of Delaware
Newark, Delaware, United States

Introduction: Currently, the field of robotics research is teeming with new advances that are pushing the capabilities of large-scale machines into the regime where fundamental tasks such as running, lifting, and fine motor skills are becoming easier feats to overcome. However, despite their many imaginable applications in industrial and biomedical applications, there is a lack of practical robots on the nano- and microscale, that could carry out operations currently limited to expensive and difficult-to-use systems such as optical, magnetic, and acoustic tweezers. Thereby, we reported the design and implementation of a technique for manipulating microscale objects via an acoustically powered, bubble-actuated, magnetically steerable microrobot. we build upon our previous work on acoustic microrobots and demonstrate their applications to mammalian cellular manipulation and targeted payload delivery. In the presence of an acoustic field and magnetic field, the bullet-shaped microrobots could be navigated. To demonstrate cell targeting, manipulation, and cargo delivery, we use the Human Embryonic Kidney (HEK) cell line. Additionally, we successfully demonstrate the cargo release to the target HEK site by pulling polystyrene particles as cargo.

Materials and

Methods: A 1.8 MHz transducer (STEMinc) was fixed to the bottom of a glass microscope slide or silicon wafer and two Kapton polyimide circles were added to the other side, just next to the transducer to allow for use in an inverted microscope. These circles can be used to create a chamber, and scratching the surface of the wafer used to fabricate the microrobots with a pipette tip filled with 7 μL of water and transferring that to the chamber gives independent, operational robots that typically operate between 1.0 and 1.6 MHz at 1 Vpp or less (normally 200mVpp), although higher operating voltages are certainly possible.

Results, Conclusions, and Discussions: The combination of efficient, precisely directional, and independent propulsion makes the bubble-based microswimmers an ideal tool for selective manipulation of objects. Moreover, their biocompatibility means that they can be easily integrated into cellular environments, especially mammalian cells. For demonstrating the steering of microrobots to mammalian cells 2% w/v solution of the acoustic microrobots was prepared in DMEM. 5 μL of the microrobot solution along with 5 μL of the HEK cellular solution in DMEM was added to the chamber. Once the desired cell was located, a microrobot was identified and it was tilted using the permanent magnet. Then the magnet was used to steer the microrobot to the identified cell. The microrobots can also be used for targeted delivery of payloads to the cells. For a demonstration of cargo pickup and delivery, we combined 2.5 μL of microrobots in water with 2.5 μL of cargo particle (3 μm polystyrene particle) solution. This solution was added to the chamber along with 5 μL of HEK cellular solution. The microrobot was able to pick up the cargo due to the ’pulling’ mode. Again, this mode operates at slightly larger acoustic pressure, at which the microrobots exhibit non-negligible attractive forces on the particles around them.
In this situation, the robot can load and transport the cargo particles by moving toward their centers of mass and trapping them via the secondary Bjerknes force. A microrobot propelled by a 1 kPa acoustic pressure field and steered to grab only the target particle. The microrobot attracts the particle and then steers it across almost the entire diameter of the fluid chamber, which is about 5 mm. The cargo particle is then steered by the microrobot and delivered to a targeted HEK cell. Lastly, the cargo can also be easily released by directing the microrobot away from it.

Here, we demonstrate the utility of using a bubble-powered microswimmer as a microscopic robot for simple, high-speed, bio-compatible cellular manipulation and cargo delivery. We have shown superior control over these microrobots using only a strong handheld magnet and a ceramic transducer driven at biologically relevant ultrasound voltages and frequencies.

Acknowledgements (Optional):