Review on Fabrication and Manipulation of Scaffold and Ciliary Microrobots

A microrobot is a tiny structure that can be remotely controlled to perform a mission which is a definition of a robot. In general, the size of a microrobot is from few micrometers to few millimeters. Microrobots for biomedical applications should be able to swim in a fluidic environment of the body including circulatory, the urinary, and nerve system by external magnetic fields and field gradient [1-4]. These microrobots are expected to perform various biomedical applications including targeted cell transportation, precise drug delivery, opening blocked blood vessels, micro-surgery, sensing, and scaffolding [1-6]. Among these applications, targeted drug delivery and cell transportation can be implemented by fabrication of biocompatible and magnetically controllable microrobots [2, 3, 6]. The structures of the microrobots can be fabricated by various materials such as SU-8, IP-Dip, IP-L, silicon, etc. [7-11] Especially, SU-8, IP-Dip, and IP-L are being used to fabricate precise three-dimensional (3D) microrobots using a 3D laser lithography system [2, 4, 8, 9, 11-14]. The polymer structures of the microrobots should be coated with nickel and titanium layers after fabrication for magnetic wireless control and biocompatibility of the microrobots [2, 9, 11]. The microrobots with a magnetic layer can be precisely controlled by external magnetic fields generated by a magnetic coil system. Relevant magnetic fields or field gradient should be used to control a microrobot based on the driving mechanism of each microrobot [15-18]. Many research works have been focused on only implementation of locomotion with a simple structure or a magnet because of the difficulty of fabrication and assembly of small structures. In this review, 3D laser lithography will be briefly introduced to explain the fabrication method for some of the biomedical microrobots. The driving mechanism for each microrobot will also be introduced with two magnetic Corresponding Author: Hongsoo Choi, Ph. D. Daegu Gyeongbuk Institute of Science and Technology (DGIST) 50-1 Sang-Ri, Hyeonpung-Myeon, Dalseong-Gun Daegu, 711-873, KOREA Tel: +82-53-785-6212 Fax: +82-53-785-6209 E-mail: mems@dgist.ac.kr