  We demonstrate a facile technique to scratch, manipulate, and solder
exfoliated flakes of layered 2D materials using a microneedle probe attached to
the precision xyz manipulators under an optical microscope. We show that the
probe can be used to scratch the flakes into a designated shape with a
precision at micrometer scales, move, rotate, roll-up, and exfoliate the flakes
to help building various types of heterostructures, and form electric contacts
by directly drawing/placing thin metal wires over the flake. All these can be
done without lithography and etching steps that often take long processing time
and involve harmful chemicals. Moreover, the setup can be easily integrated
into any van der Waals assembly systems such as those in a glove box for
handling air/chemical-sensitive materials. The microneedle technique
demonstrated in this study therefore enables quick fabrications of devices from
diverse 2D materials for testing their properties at an early stage of research
before conducting more advanced studies and helps to build different types of
van der Waals heterostructures.
