Membrane-based Separations

Due to its inherent stochasticity, brittle fracture is seldom used as a nanofabrication
method. However, the imposition or templating of a specific strain field can guide fracture along
a pre-set design. Herein, we show that this autoperforation provides a means of spontaneous
assembly for 2D surfaces. Chemical vapor deposited mono- and bi-layer graphene, molybdenum
disulfide (MoS2), or hexagonal boron nitride (hBN) autoperforate into circular envelopes when
sandwiching a microprinted polymer spot, allowing lift-off and assembly into solution. The
resulting composite microparticles have two independently addressable, external Janus faces
that we show can function as an intraparticle array of parallel, two terminal electronic devices. As
an example, we print a 0.9 wt% black phosphorous (BP) nanoflake in polystyrene (PS) latex ink
into mono-layer graphene sandwich particles, resulting in micro-particles possessing non-volatile,
15 bit memory storage via a spatially addressable memresistor array throughout the particle
interior. Such particles form the basis of free floating devices capable of collecting and storing
digital information in their environment. The 2D envelopes demonstrate remarkable chemical and
mechanical stability during 4 months of preservation in aqueous media. They also survive a highly
acidic gastrointestinal environment, as well as aerosolization over 0.3 meters and re-collection.
Autoperforation of 2D materials into such envelope structures open the door to precise
compositing of particulate devices, extending nanoelectronics into previously inaccessible
environments.