Search for: All records

Functional imaging in freely moving animals with genetically encoded voltage indicators (GEVIs) will open new capabilities for neuroscientists to study the behavioral relevance of neural activity with high spatial and temporal precision. However, miniaturization of an imaging system with sufficient collection efficiency to resolve the small changes in fluorescence yield from voltage spikes, as well as the development of efficient image sensors that are sufficiently fast to capture them, has proven challenging. We present a miniaturized microscope designed for voltage imaging, with a numerical aperture of 0.6, a 250 µm field of view, and a 1.3-1.6 mm working distance that weighs 16.4 g. We show it is capable of imagingin vivovoltage spikes from Voltron2 with a spike peak-to-noise ratio >3 at a framerate of 530 Hz. 

Abstract The challenge of fabricating transparent and conductive (T/C) films and patterns for applications in flexible electronics, touch screens, solar cells, and smart windows remains largely unsolved. Traditional fabrication techniques are complex, costly, time‐consuming, and struggle to achieve the necessary precision and accuracy over electronic and optical properties. Here, hypersurface photolithography (HP), which integrates microfluidics, a digital micromirror device, and photochemical surface‐initiated polymerizations is used to create polymer brush patterns. The high‐throughput optimization enabled by HP provides conditions to fabricate patterns composed of cross‐linked polymer brushes containing Au‐binding 2‐vinylpyrrolidine (2VP) groups with precise control over the height and the composition at each pixel. Au nanoparticles (AuNPs) are incorporated into the polymer brush patterns through in situ reduction of Au ions, resulting in T/C composite AuNP/polymer brush patterns. The sheet resistance at 100 mA of a 2VP‐AuNP‐functionalized patterns on a glass substrate is 0.42 Ω sq⁻¹with 86% transmittance of visible light. Additional patterns demonstrate multiplexing by copatterning rhodamine B functionalized fluorescent polymer brushes and AuNP/polymer brush conductive domains. This work solves the challenge of creating T/C films by forming metal‐polymer composites from polymer brush patterns, offering a scalable solution for electronic and optical device development and fabrication. 

Abstract Micro light emitting diodes (MicroLEDs) provide unrivaled luminance and operating lifetime, which has led to significant activity using devices for display and non‐display applications. The small size and high power density of microLEDs, however, causes increased adverse heating effects that can limit performance. A new generation of electrically insulating high thermal conductivity materials, such as alumina, is proposed to mitigate these thermal effects when used as a substrate as an alternative to glass. This strategy can then be used as a method of passive heat sinking to improve the overall performance of the microLED. In this work, a newly available material, an 80 micron thick alumina ceramic substrate, is shown to yield a 30 % improvement on average in the maximum current drive over a glass substrate. 

Polyvinylidene difluoride trifluoroethylene (PVDF-TrFE) has received widespread application in flexible electronics and biomedical devices but is limited in its sensing modalities to piezoelectricity and pyroelectricity. The addition of optically or magnetically active nanoparticles could provide additional sensing modalities in the same element, which could drive miniaturization of such sensors. Europium barium titanate (EBTO) is one such optically active nanoparticle that could add functionality to such a nanocomposite. In this work, multifunctional nanocomposites of PVDF-TrFE and EBTO are successfully synthesized and characterized for their material and electronic properties. The nanocomposite in this work is the first known multifunctional nanocomposite with PVDF-TrFE and a fluorescent nanoparticle. 

We discuss optical sectioning structured illumination microscopy (OS-SIM) for functional GCaMP8f imaging in the CA1 hippocampal region of awake mice. We demonstrate OS-SIM implementation to reduce out-of-focus signal contamination in recordings taken at 200 Hz. 

Optical sectioning structured illumination microscopy (OS-SIM) provides optical sectioning capability in wide-field microscopy. The required illumination patterns have traditionally been generated using spatial light modulators (SLM), laser interference patterns, or digital micromirror devices (DMDs) which are too complex to implement in miniscope systems. MicroLEDs have emerged as an alternative light source for patterned illumination due to their extreme brightness capability and small emitter sizes. This paper presents a directly addressable striped microLED microdisplay with 100 rows on a flexible cable (70 cm long) for use as an OS-SIM light source in a benchtop setup. The overall design of the microdisplay is described in detail with luminance-current-voltage characterization. OS-SIM implementation with a benchtop setup shows the optical sectioning capability of the system by imaging within a 500 µm thick fixed brain slice from a transgenic mouse where oligodendrocytes are labeled with a green fluorescent protein (GFP). Results show improved contrast in reconstructed optically sectioned images of 86.92% (OS-SIM) compared with 44.31% (pseudo-widefield). MicroLED based OS-SIM therefore offers a new capability for deep tissue widefield imaging.