Magnetic exchange field in magnetic multilayers can potentially reach tens or even hundreds of Tesla. 6 The single-atomic-layer (2D) materials, such as graphene, mono-layer WS 2 etc., is expected to experience the strongest MEF in heterostructures with magnetic insulators due to the short-range nature of magnetic exchange coupling. 4 2D material/magnetic insulator heterostructures enable local spin modulation by magnetic gates, 4,5,7 and the realization of efficient spin generation for spintronic applications. 8,9 As a proof of concept, here we demonstrate substantial MEF and spin polarization in CVD graphene/EuS heterostructures. We have chosen EuS as a model magnetic insulator because of its wide band-gap (1.65 eV), large exchange coupling J~10 meV, and large magnetic moment per Eu ion ௭~7 , 10 yielding large estimated exchange splitting ௭ in graphene. 4,5 EuS has also been shown to spin-polarize quasiparticles in materials including superconductors and topological insulators. 6,11 The strength of the MEF depends critically on the interface and EuS quality, 12,13 which we optimize with an in-situ cleaning and synthesis process (Methods and Fig. 1a). In contrast to other means, such as defect-or adatom-induced spin polarization, 14,15 depositing insulating EuS well preserves graphene's chemical bonding, confirmed by Raman spectroscopy (Fig. 1b) (Fig. S5-1), indicative of high graphene quality and well-preserved Dirac band structure.We utilize Zeeman spin-Hall effect (ZSHE) to probe the MEF in graphene which splits the Dirac cone via Zeeman effect and generates electron-and hole-like carriers with opposite 4 spins near the Dirac point ( Fig. 2a right panel). 8,9 Under a Lorentz force, these electrons and holes propagate in opposite directions, giving rise to a pure spin current and non-local voltage ( Fig. 2a left panel). We measure the non-local resistance of ZSHE using the device configuration in Fig. 2a where ௫ is the MEF. We further define the parameter :where ௭ denotes the Zeeman energy at the reference field . Given , deriving of graphene/AlO x is straightforward because ௭ is solely determined by . The inset of Fig. 3(b) shows the calculated using T, a proper reference field as we will explain below.To derive of graphene/EuS, we note that according to the theory of ZSHE, 9,17 depends on sample mobility, while other sample-dependents terms (including spin relaxation length, density of thermally activated carriers and Fermi velocity) cancel out (see S3 in SI). The mobility difference between our graphene/EuS and graphene/AlO x samples is~25% (see S1 in SI), which would only yield a~10% correction to  (see S3 in SI). Since~10% difference is 6 small, for an order-of-magnitude estimate of the MEF, we adopt the value of graphene/AlO x for graphene/EuS as an approximation. We then evaluate E Z in graphene/EuS usingTo obtain the lower bound of , we approximate , ignoring the ௫contribution. This constrains us to use a small such that ௫ is small. Meanwhile, should be high enough to ensure that , is much large...

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. These microscale opto-electrically transduced electrodes (MOTEs) are powered by, and communicate through an optical interface, simultaneously enabling high temporal-resolution electrical measurements without a tether or a bulky RF coil. The MOTE presented here is 250 μm × 57 μm, consumes 1 of electrical power, and is capable of capturing and encoding neural signals before transmitting the encoded signals. The measured noise floor is as low as 15 μVrms at a 15 KHz bandwidth.

We present a platform for parallel production of standalone, untethered electronic sensors that are truly microscopic, i.e., smaller than the resolution of the naked eye. This platform heterogeneously integrates silicon electronics and inorganic microlight emitting diodes (LEDs) into a 100-μm-scale package that is powered by and communicates with light. The devices are fabricated, packaged, and released in parallel using photolithographic techniques, resulting in ∼10,000 individual sensors per square inch. To illustrate their use, we show proof-of-concept measurements recording voltage, temperature, pressure, and conductivity in a variety of environments.

Autonomous robots—systems where mechanical actuators are guided through a series of states by information processing units to perform a predesigned function—are expected to revolutionize everything from health care to transportation. Microscopic robots are poised for a similar revolution in fields from medicine to environmental remediation. A key hurdle to developing these microscopic robots is the integration of information systems, particularly electronics fabricated at commercial foundries, with microactuators. Here, we develop such an integration process and build microscopic robots controlled by onboard complementary metal oxide semiconductor electronics. The resulting autonomous, untethered robots are 100 to 250 micrometers in size, are powered by light, and walk at speeds greater than 10 micrometers per second. In addition, we demonstrate a microscopic robot that can respond to an optical command. This work paves the way for ubiquitous autonomous microscopic robots that perform complex functions, respond to their environments, and communicate with the outside world.

In vivo, chronic neural recording is critical to understand the nervous system, while a tetherless, miniaturized recording unit can render such recording minimally invasive. We present a tetherless, injectable micro-scale opto-electronically transduced electrode (MOTE) that is ∼60µm × 30µm × 330µm, the smallest neural recording unit to date. The MOTE consists of an AlGaAs micro-scale light emitting diode (µLED) heterogeneously integrated on top of conventional 180nm complementary metal-oxide-semiconductor (CMOS) circuit. The MOTE combines the merits of optics (AlGaAs µLED for power and data uplink), and of electronics (CMOS for signal amplification and encoding). The optical powering and communication enable the extreme scaling while the electrical circuits provide a high temporal resolution (<100µs). This paper elaborates on the heterogeneous integration in MOTEs, a topic that has been touted without much demonstration on feasibility or scalability. Based on photolithography, we demonstrate how to build heterogenous systems that are scalable as well as biologically stable-the MOTEs can function in saline water for more than six months, and in a mouse brain for two months (and counting). We also Manuscript