The field of miniature mechanical oscillators is rapidly evolving, with emerging applications including signal processing, biological detection1 and fundamental tests of quantum mechanics2. As the dimensions of a mechanical oscillator shrink to the molecular scale, such as in a carbon nanotube resonator3–7, their vibrations become increasingly coupled and strongly interacting8,9 until even weak thermal fluctuations could make the oscillator nonlinear10–13.

Recording neural activity in live animals in vivo with minimal tissue damage is one of the major barriers to understanding the nervous system. This paper presents the technology for a tetherless opto-electronic neural interface based on 180 nm CMOS circuits, heterogeneously integrated with an AlGaAs diode that functions as both a photovoltaic and light emitting diode.

Tensioned graphene membranes are of interest both for fundamental physics and for applications ranging from water filtration to nanomechanical resonators. It is generally assumed that these membranes have a stretching modulus of about 340 N/m and a negative, temperature-independent thermal expansion coefficient due to transverse phonon modes. In this paper, we study the two-dimensional Young's modulus and thermal expansion of graphene as functions of temperature by using laser interferometry to detect the static displacement of the membrane in a cryostat.

Recording neural activity in live animals in vivo poses several challenges. Electrical techniques typically require electrodes to be tethered to the outside world directly via a wire, or indirectly via an RF Coil [1], which is much larger than the electrodes themselves. Tethered implants result in residual motion between neurons and electrodes as the brain moves, and limits our ability to measure from peripheral nerves in moving animals, especially in smaller organisms such as zebra fish or fruit flies.

Origami-inspired fabrication presents an attractive platform for miniaturizing machines: thinner layers of folding material lead to smaller devices, provided that key functional aspects, such as conductivity, stiffness, and flexibility, are persevered. Here, we show origami fabrication at its ultimate limit by using 2D atomic membranes as a folding material. As a prototype, we bond graphene sheets to nanometer-thick layers of glass to make ultrathin bimorph actuators that bend to micrometer radii of curvature in response to small strain differentials.

We present a technique to precisely measure the surface energies between two-dimensional materials and substrates that is simple to implement and allows exploration of spatial and chemical control of adhesion at the nanoscale. As an example, we characterize the delamination of single-layer graphene from monolayers of pyrene tethered to glass in water and maximize the work of separation between these surfaces by varying the density of pyrene groups in the monolayer. Control of this energy scale enables high-fidelity graphene-transfer protocols that can resist failure under sonication.

Excitons, the bound states of an electron and a hole in a solid material, play a key role in the optical properties of insulators and semiconductors. Here, we report the observation of excitons in bilayer graphene (BLG) using photocurrent spectroscopy of high-quality BLG encapsulated in hexagonal boron nitride. We observed two prominent excitonic resonances with narrow line widths that are tunable from the mid-infrared to the terahertz range.

A major achievement of the past decade has been the realization of macroscopic quantum systems by exploiting the interactions between optical cavities and mechanical resonators. In these systems, phonons are coherently annihilated or created in exchange for photons. Similar phenomena have recently been observed through phonon-cavity coupling - energy exchange between the modes of a single system mediated by intrinsic material nonlinearity.

To determine the thermal noise limit of graphene biotransistors, we have measured the complex impedance between the basal plane of single-layer graphene and an aqueous electrolyte. The impedance is dominated by an imaginary component but has a finite real component. Invoking the fluctuation-dissipation theorem, we determine the power spectral density of thermally driven voltage fluctuations at the graphene/electrolyte interface. The fluctuations have 1/fp dependence, with p = 0.75-0.85, and the magnitude of fluctuations scales inversely with area.

We couple magnetic tweezer techniques with standard lithography methods to make magnetically actuated single-walled carbon nanotube (SWNT) devices. Parallel arrays of 4-10 m-long SWNT cantilevers are patterned with one end anchored to the substrate and the other end attached to a micron-scale iron magnetic tag that is free to move in solution. Thermal fluctuations of this tag provide a direct measurement of the spring constant of the SWNT cantilevers, yielding values of 10-7-10-8 N/m.