Dispersion characterization of magnetic actuated needleless injections with particle image velocimetry

  • Mavis Qin Ying Yee
  • Bok Seng Yeow
  • Hongliang RenEmail author
Original Article


Conventional needle-based approaches in intravitreal drug delivery carry needle-stick-injury risk and could scare patients (belonephobia). Alternatively, our group has explored the application of an electromagnetic needleless injector in this paper. This work aims to improve intravitreal drug delivery, which in the future could assist physicians with automation and benefit patients by providing a needleless approach. Electromagnetic needleless intravitreal injections lack quantification studies. We investigate the delivery properties of the needleless injector where the characterization can be used to refine the design parameters of the prototype in subsequent iterations. Experiments were performed to characterize the injectant delivered from the electromagnetic needleless injector. Penetration tests were conducted to observe the influences of various injection barriers and tissues. Ultrasonic imaging modality was explored for future applications of the prototype. The dispersion of the injectant was controllable where injection depth and distribution is dependent on the input voltage. The synthetic barriers highlighted significant energy losses for penetration (maximum velocity falls from 4.46 to 1.57 mm/s with a 0.1-mm barrier). The biological barriers were difficult to penetrate with the current prototype. Our results indicate that the current electromagnetic injector offers controllable dispersion (depth and distribution) correlated with input voltages, which should have increased injection power for use with biological tissue. Ultrasonic imaging modality produced velocity profiles comparable to the optical approach which is promising for future in vivo studies. The influences of injection barriers should be further investigated in in vivo experiments with ultrasonic imaging modalities.

Graphical abstract



Needleless injection Vitreous humor Optical Ultrasound Halbach Array Particle image velocimetry Retinal Penetration Velocity Power 


Funding information

The Singapore Academic Research Fund provided financial support under Grant R-397-000-173-133 (Magnetically Actuated Micro-robotics) and National Natural Science Foundation of China NSFC grant 51405322, awarded to Dr. Hongliang Ren.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Research involving human participants and/or animals

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of retrospective study, formal consent is not required. This article does not contain any studies with animals performed by any of the authors.

Informed consent

Informed consent was obtained from all individual participants included in the study. Any participation in the study is voluntary and identities of participants are kept anonymous.

Supplementary material

11517_2019_2035_MOESM1_ESM.docx (311 kb)
ESM 1 (DOCX 311 kb)


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Copyright information

© International Federation for Medical and Biological Engineering 2019

Authors and Affiliations

  1. 1.Department of BioMedical EngineeringNational University of SingaporeSingaporeSingapore
  2. 2.Bachelor of Engineering from the National University of SingaporeSingaporeSingapore
  3. 3.Chinese University of Hong KongSha TinHong Kong

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