Laser Controlled 65 Micrometer Long Microrobot Made of Ni‐Ti Shape Memory Alloy

Abstract

Existing proofs-of-concept have shown that microrobots can perform cell manipulation and enucleation, [4] selective gene transmission, [5] in vivo biopsy, [6] and cellular stimulation. [7] As the robots are too tiny to carry motors, control devices, and energy storages, they are commonly propelled using a magnetic gradient imparting a direct pull [8] or using a homogenous rotating field that in turn makes the microrobots rotate. [9] Developments in manufacturing technology made major contributions to the abovementioned achievements. Manufacturing processes can be categorized as top-down or bottom-up. The bottomup methods, such as precision additive manufacturing are widely applied. [10,11] Even, it tries to utilize smart material for developing 4D printing. [12] Two-photon lithography is a representative, additive microscale manufacturing process that uses laser scanning to polymerize photosensitive materials. Although this method can create a complete 3D structure, limitations exist on material selection, mostly polymers.On the other hand, top-down processes including focused ion beam (FIB) milling can be used to fabricate robots from a range of materials, including biocompatible or biodegradable materials. Furthermore, smart materials, such as shape memory alloys (SMAs), shape memory polymers (SMPs), and piezoelectric materials, can be used as actuators of the microrobot.The creation of movement in liquid is the first challenge when miniaturizing robots to microscales. As the size shrinks, the low Reynolds number due to more viscous effect and Brownian motion become major challenges. An efficient microscale robot thus requires a swimming strategy operative at low Reynolds numbers, and a navigation strategy that overcomes Brownian motion. As a traditional powering method to robot cannot be fitted at such small-scales, innovative design and actuation methods are required to satisfy the challenges of power and actuation. Various microrobots highlighting specific navigation principles have been developed over the past decade. [2] There are three categories of navigation strategies in microrobots: self-propulsion, external propulsion, and a hybrid strategy. [13] Self-propulsion is generated by result of local, smallscale chemical reactions on the robot surface; chemical energy is converted into kinetic energy. Generating local concentration Microrobotics has many potential applications, such as environmental remediation, in the biomedical arena. However, existing microrobots exhibit practical limitations including inadequate biocompatibility and imprecise control. Here, a microrobot made of shape memory alloy (SMA) actuator which can be driven by laser scanning to perform microscale motions is introduced. The 65 µm long microrobot having crawling-like motion can demonstrate the movement with 10.0 µm s −1 of the maximum speed. The microrobot is controlled by a laser affording wireless, spatiotemporally selective capabilities. During actuation, the robot exhibits crawling-like motions including trigger via the SMA as ...

Light‐Powered Microrobots: Challenges and Opportunities for Hard and Soft Responsive Microswimmers

“…A nature‐inspired biomedical microrobot fabricated in a Ni–Ti shape memory alloy is shown in Figure 7F. [ 158 ] The metallic structure was fabricated by focused ion beam milling and mimics shrimp locomotion upon laser actuation. Its propulsion is driven by optothermal trapping forces induced by the thermophoretic response of the Ni–Ti shape memory alloy.…”

“…A nice proof‐of‐concept example is the microrobot reported by Kim et al for eye surgery. [ 158 ] At this stage, we do not foresee the use of light‐powered microrobots deep inside the human body due to the very limited tissue penetration of light. However, microrobots with hybrid magnetic and optical actuation could be suitable for performing tasks inside the human body.…”

Recent Advances in Design and Actuation of Continuum Robots for Medical Applications

“…At the same time, the electrothermal effect of SMA has the defect as low drive frequency, which limits the movement of CRs. Kim et al in Reference [107] have proposed a method that relies on the optical effect of SMA, which is still based on optothermal and optical trapping effects of laser to cause temperature change, but higher sensitivity compared to the traditional thermo effects. The micro-robot is controlled by a laser that provides wireless space and time selection.…”

“…Smart materials driven [102][103][104][105][106][107][108][109] Smart materials are usually used as raw materials for robots and play a role in the movement of robots. Under external stimuli, the robot will perform expected actions due to the properties of the material.…”

Investigating the mechanical response of microscale pantographic structures fabricated by multiphoton lithography

“…The implacable progress in 3D printing technologies has enabled the fabrication of complex 2D or 3D structures, possessing unprecedented properties. Specifically, these remarkable advances in microscale printing have enabled the design of MEMS devices, microrobotic devices [1,2], scaffolds for tissue engineering and the investigation of cellular malfunction [3] and even biomimetics and bioimplants [4]. However, despite the fact that for such domains fabrication techniques such as FIB milling [1], microstereolithography [5] or direct ink writing are highly efficient, they cannot be employed for the fabrication of highly complex 3D structures that possess features with nanoscale resolution.…”