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Spectrometers are key instruments in diverse fields, notably in medical and biosensing applications. Recent advancements in nanophotonics and computational techniques have contributed to new spectrometer designs characterized by miniaturization and enhanced performance. This paper presents a comprehensive review of miniaturized computational spectrometers (MCS). We examine major MCS designs based on waveguides, random structures, nanowires, photonic crystals, and more. Additionally, we delve into computational methodologies that facilitate their operation, including compressive sensing and deep learning. We also compare various structural models and highlight their unique features. This review also emphasizes the growing applications of MCS in biosensing and consumer electronics and provides a thoughtful perspective on their future potential. Lastly, we discuss potential avenues for future research and applications.

Complex environments, such as those found in surgical and search‐and‐rescue applications, require soft devices to adapt to minimal space conditions without sacrificing the ability to complete dexterous tasks. Stacked balloon actuators (SBAs) are capable of large deformations despite folding nearly flat when deflated, making them ideal candidates for such applications. This paper presents the design, fabrication, modeling, and characterization of monolithic, inflatable, soft SBAs. Modeling is presented using analytical principles based on geometry and then using conventional and real‐time finite‐element methods. Both one and three degree‐of‐freedom (DoF) SBAs are fully characterized with regard to stroke, force, and workspace. Finally, three representative demonstrations show the SBA's small‐aperture navigation, bracing, and workspace‐enhancing capabilities.

Grating plays an essential role in various optical systems owing to its unique dispersion properties. In recent years, there is increasing demand to miniaturize optical systems for a wide range of field applications. Therefore, the integration of diffraction grating with MEMS technology provides an efficient way to build truly miniaturized optical systems. Till now, MEMS diffraction gratings have mainly been explored in two directions, namely MEMS scanning gratings and MEMS tunable gratings. MEMS scanning gratings are constructed with a variety of MEMS actuators to drive a grating platform to scan across the target, and they play a significant role in various scanning systems. Meanwhile, the dispersive properties of grating scanners make them attractive in wavelength sensing applications, including spectrometers and hyperspectral imaging systems. Tunable gratings typically employ MEMS actuators to dynamically change the diffraction properties, thus tuning its wavelength sensitivity for a specific application. Thus, this review will introduce these two types of MEMS gratings in detail and evaluate their efficiency and advantages in various fields.

Single-pixel imaging technology is an attractive technology considering the increasing demand of imagers that can operate in wavelengths where traditional cameras have limited efficiency. Meanwhile, the miniaturization of imaging systems is also desired to build affordable and portable devices for field applications. Therefore, single-pixel imaging systems based on microelectromechanical systems (MEMS) is an effective solution to develop truly miniaturized imagers, owing to their ability to integrate multiple functionalities within a small device. MEMS-based single-pixel imaging systems have mainly been explored in two research directions, namely the encoding-based approach and the scanning-based approach. The scanning method utilizes a variety of MEMS scanners to scan the target scenery and has potential applications in the biological imaging field. The encoding-based system typically employs MEMS modulators and a single-pixel detector to encode the light intensities of the scenery, and the images are constructed by harvesting the power of computational technology. This has the capability to capture non-visible images and 3D images. Thus, this review discusses the two approaches in detail, and their applications are also reviewed to evaluate the efficiency and advantages in various fields.