Sub-pixel shifting technologies are attractive for enhancing the resolution of cameras and projectors. Conventional techniques, such as wobulation and pixel shift, rely on mechanical moving parts or cumbersome optical systems. As a solution, we demonstrate "electrowetting wobulation," in which a tunable electrowetting prism is used to laterally shift a projected image. This technique overcomes challenges of other pixel shifting techniques, as the electrowetting prism is transmissive, can achieve high framerates, and has no mechanical moving parts. We apply electrowetting wobulation to an optical sectioning structured illumination microscope and demonstrate lateral shifting of a structured pattern while maintaining optical sectioning, which requires high quality images. We characterize the optical sectioning strength across multiple spatial frequencies, as well as demonstrate enhanced sectioning in an autofluorescent pollen grain, and find electrowetting wobulation is a promising technology to improve the resolution of conventional imaging systems.

This work demonstrates a microLED light source for optical sectioning structured illumination microscopy (OS-SIM). A bottom-emitting design is employed to improve the uniformity and intensity of emission by removing the anode contact from the optical path. This design facilitates the addition of a potential equalizing and light-reflecting layer to the top surface of the light source. The irradiance, uniformity of light emission, and contrast ratio are characterized.

We demonstrate a microLED light source for optical sectioning structured illumination microscopy (OS-SIM). A bottom-emitting design is employed to improve the uniformity and intensity of emission by removing the anode contact from the optical path. This design facilitates the addition of a potential equalizing and light-reflecting layer to the top surface of the light source. The irradiance, uniformity of light emission, and contrast ratio of the light source are characterized. A system demonstration is performed with the light source integrated into a fluorescence microscope and used for OS-SIM imaging.

Commercial optical technologies have an increasing need for an accurate, in-situ beam locator to ensure laser alignment during operation. In this work, gallium nitride LEDs with indium gallium nitride quantum wells are leveraged to create a fully transparent two-dimensional position sensitive detector (PSD). Two different architectures are developed and characterized. Fabricated devices are shown to successfully and repeatably locate 405 nm laser light in two dimensions in the PSD area with a limit of detection of 8.4 μm while maintaining approximately 3% linearity.

We demonstrate a new implementation of structured illumination microscopy, in which a tunable electrowetting prism is incorporated in the microscope to “wobulate” the structured illumination on the sample. Optical sectioning is demonstrated with fluorescent beads.

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.

After some two decades of advances in manufacturing processes, microLEDs have the quality and capabilities necessary for many display applications.

This work discusses microLED arrays as light sources for implementing optical sectioning structured illumination microscopy (OS‐SIM) and targeted illumination (TI) for neural imaging applications. We demonstrated a microstripe array to generate patterned light for OS‐SIM and an individually addressable 20 × 20 microLED array as a light source for implementing TI in a widefield imaging setup.

We present a method of monolithically integrating GaN microLEDs with an IGZO TFT backplane to produce an activematrix microdisplay. After discussion of the fabrication process, individual LEDs, TFTs, and the integrated system are characterized. Results demonstrate a 32x32 pixel, 78.4 PPI microdisplay with luminance exceeding 1500 nits. This type of monolithic microdisplay forges the path forward for future high luminance integrated displays to enable augmented and mixed reality applications.

This paper presents a method of monolithically integrating gallium nitride micrometer-scale light-emitting diodes (microLEDs) with an indium gallium zinc oxide (IGZO) thin-film transistor (TFT) backplane to produce an active-matrix microdisplay. After discussion of the fabrication process, individual LEDs, TFTs, and the integrated system are characterized. Results demonstrate a 32 x 32 pixel, 78.4 PPI microdisplay with luminance exceeding 1500 nits. The dynamic set and hold behaviors of the active-matrix pixel circuit are analyzed to verify the applicability of this technology for use in high and low refresh rate displays. This paper presents a method of monolithically integrating GaN microLEDs with an IGZO TFT backplane to produce an active-matrix microdisplay. After reviewing the fabrication process, individual LEDs, TFTs, and the integrated system are characterized. Results demonstrate a 32 x 32 pixel, 78.4 PPI microdisplay with luminance exceeding 1500 nits and a retention time characterized by a 0.93 s time constant. image

In this paper, an implantable planar inverted-F antenna (PIFA) operating in the industrial, scientific, and medical (ISM) band (915 MHz) is proposed. It was designed and fabricated on a flex printed circuit board (PCB) platform and is capable of full integration with driving circuitry for biopotential measurements. The antenna's dimensions (26mm x 54mm x 0.2mm) were optimized for implantation and use in Norway rats to facilitate wireless biomedical testing. In a live rodent model, the antenna showed a peak S11 of -17.94 dB at its resonance frequency with a peak gain of -3.94 dBi, an efficiency of 14.86%, and a -10 dB bandwidth of 42.21 MHz. To the best of our knowledge, this paper marks the first time a 915 MHz antenna was specifically built for implantation using a flex PCB substrate and a parylene-C insulating coating.

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.

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.

MicroLEDs offer an extraordinary combination of high luminance, high energy efficiency, low cost, and long lifetime. These characteristics are highly desirable in various applications, but their usage has, to date, been primarily focused toward next-generation display technologies. Applications of microLEDs in other technologies, such as projector systems, computational imaging, communication systems, or neural stimulation, have been limited. In non-display applications which use microLEDs as light sources, modifications in key electrical and optical characteristics such as external efficiency, output beam shape, modulation bandwidth, light output power, and emission wavelengths are often needed for optimum performance. A number of advanced fabrication and processing techniques have been used to achieve these electro-optical characteristics in microLEDs. In this article, we review the non-display application areas of the microLEDs, the distinct opto-electrical characteristics required for these applications, and techniques that integrate the optical and electrical components on the microLEDs to improve system-level efficacy and performance.

Studies of electrosensory systems have led to insights into a number of general issues in biology. However, investigations of these systems have been limited by the inability to precisely control spatial patterns of electrosensory input. In this paper, an electrode array and a system to selectively stimulate spatially restricted regions of an electroreceptor array are presented. The array has 96 channels consisting of chrome/gold electrodes patterned on a flexible parylene‐C substrate and encapsulated with another parylene‐C layer. The conformability of the electrode array allows for optimal current driving and surface interface conditions. Recordings of neural activity at the first central processing stage in weakly electric mormyrid fish support the potential of this system for high spatial resolution stimulation and mapping of electrosensory systems.

Conducting remote laboratory‐based courses in electronics is a major challenge primarily because of the hardware requirements. This paper describes a laboratory course on information display technologies specially designed and implemented for remote learning. The course was successfully offered during the COVID‐19 lockdown and has an online instruction component to introduce the concepts, as well as a laboratory part involving hands‐on work. The course covers experiments on fundamental concepts related to perception and color, liquid crystal displays (LCD), light‐emitting diodes (LEDs), and a final project where a mechanical display is designed and built. Course assessment based on an anonymous survey shows the hands‐on work enhanced the student learning and improved course understanding from an average of 2.5/5 measured at the start of the course to 4/5 at the end.