Programmable assembly of heterogeneous microparts by an untethered mobile capillary microgripper

Abstract

At the sub-millimeter scale, capillary forces enable robust and reversible adhesion between biological organisms and varied substrates. Current human-engineered mobile untethered micromanipulation systems rely on forces which scale poorly or utilize gripper-part designs that promote manipulation. Capillary forces, alternatively, are dependent upon the surface chemistry (which is scale independent) and contact perimeter, which conforms to the part surface. We report a mobile capillary microgripper that is able to pick and place parts of various materials and geometries, and is thus ideal for microassembly tasks that cannot be accomplished by large tethered manipulators. We achieve the programmable assembly of sub-millimeter parts in an enclosed three-dimensional aqueous environment by creating a capillary bridge between the targeted part and a synthetic, untethered, mobile body. The parts include both hydrophilic and hydrophobic components: hydrogel, kapton, human hair, and biological tissue. The 200 μm untethered system can be controlled with five-degrees-of-freedom and advances progress towards autonomous desktop manufacturing for tissue engineering, complex micromachines, microfluidic devices, and meta-materials.

A Monolithic Force‐Sensitive 3D Microgripper Fabricated on the Tip of an Optical Fiber Using 2‐Photon Polymerization

“…[13] A number of reports have been published demonstrating the use of this technique to fabricate a wide range of different microrobots, the most popular of which are magnetically steered flagella-like robots. [14][15][16] Further noteworthy advances in the area include steering of microrobots via optical trapping, [17,18] assembly using capillary forces, [19] and catalytic bubble generation for self-propulsion. [20] Different target applications require appropriate methods for actuation (i.e., movement) and these can typically be categorized as either global or local actuation.…”

“…A number of reports have been published demonstrating the use of this technique to fabricate a wide range of different microrobots, the most popular of which are magnetically steered flagella‐like robots . Further noteworthy advances in the area include steering of microrobots via optical trapping, assembly using capillary forces, and catalytic bubble generation for self‐propulsion …”

Pros and Cons: Magnetic versus Optical Microrobots

“…Magnetic microrobots are typically fabricated by molding22,43–46 magnetic micro/nanoparticle–polymer composites into 2D or 3D templates that are fabricated by optical lithography and two‐photon polymerization techniques, laser micromachining‐based cutting of magnetic sheets,47–50 and two‐photon polymerization‐based direct 3D printing (additive micromanufacturing) in the case of SPION‐based photocurable polymer composite materials 26,27,29,51. In the direct 3D‐printing method, there is a maximum nanoparticle density limit to not interfere with the two‐photon polymerization process,29 which limits the maximum volume of the magnetic material of such magnetic robots.…”

An Evaporative Initiated Chemical Vapor Deposition Coater for Nanoglue Bonding

“…These bonding techniques are general and may be useful in future MEMS and microfluidic device fabrication. For example, with the advancements in 3D printing and robotic assembly, future devices may be 3D printed in a standard acrylic with microstructures of other potentially non‐planar or thin materials precisely positioned and “nanoglued” in place …”