Seongjun Park

To understand the underlying mechanisms of progressive neurophysiological phenomena, neural interfaces should interact bi-directionally with brain circuits over extended periods of time. However, such interfaces remain limited by the foreign body response that stems from the chemo-mechanical mismatch between the probes and the neural tissues. To address this challenge, we developed a multifunctional sensing and actuation platform consisting of multimaterial fibers intimately integrated within a

Lamellae-forming polystyrene-block-poly(methyl methacrylate) films were directed to assemble with perpendicularly oriented domains and long-range order in confining grooves (see figure), with preferential and neutral wetting in sidewalls and bottoms, respectively. The assembled films were highly amenable for pattern transfer by reactive-ion etching.

We have developed a model to predict the chemical reactivity of carbon nanotubes (CNTs) quantitatively from their initial structures. The parameters, universal for each reaction, of the model can be obtained from a graphene sheet analysis. The chemical reactivity of hydrogenation, hydroxylation, and fluorination were predicted within 0.1−0.3 eV errors, compared with first principle simulation results. The model also predicted the enhanced chemical reactivity of mechanically bent CNTs. The predic

2D semiconductors, especially transition metal dichalcogenide (TMD) monolayers, are extensively studied for electronic and optoelectronic applications. Beyond intensive studies on single transistors and photodetectors, the recent advent of large-area synthesis of these atomically thin layers has paved the way for 2D integrated circuits, such as digital logic circuits and image sensors, achieving an integration level of ≈100 devices thus far. Here, a decisive advance in 2D integrated circuits is

Neurological and psychiatric conditions pose an increasing socioeconomic burden on our aging society. Our ability to understand and treat these conditions relies on the development of reliable tools to study the dynamics of the underlying neural circuits. Despite significant progress in approaches and devices to sense and modulate neural activity, further refinement is required on the spatiotemporal resolution, cell-type selectivity, and long-term stability of neural interfaces. Guided by the pr

Due to the limited regenerative ability of neural tissue, a diverse set of biochemical and biophysical cues for increasing nerve growth has been investigated, including neurotrophic factors, topography, and electrical stimulation. In this report, we explore optogenetic control of neurite growth as a cell-specific alternative to electrical stimulation. By investigating a broad range of optical stimulation parameters on dorsal root ganglia (DRGs) expressing channelrhodopsin 2 (ChR2), we identified

Neural interfaces have enabled significant advancements in neuroscience and paved the way for clinical applications in the diagnosis, treatment, and prevention of neurological disorders. A variety of device modalities, such as electrical, chemical and optical neural interfacing, are required for the comprehensive monitoring and modulation of neural activity. The development of recent devices with multimodal functionalities has been driven by innovations in materials engineering, especially the u

The work function of metal multilayers and monolayers on bulk metals was studied using the first principle pseudopotential method within the local density approximation in order to find a way to modulate the work function of metal gate electrodes. Various multilayer stacks and bilayer stacks of two systems, Al–Pt and Al–Ni, were examined. It was found that two or three layers of the metal are enough to shift the work function to that of the surface metal. Also, it was found that even a submonola