sequestration. [5][6][7] There are three categories of techniques that have been used to manufacture TMPs; the first (canonical) category relies on photo-or electron-beam (e-beam) lithography and etching. These methods permit unparalleled flexibility in user determination of feature size and spatial positioning, but they are expensive, require a cleanroom (and are not accessible to all users), and have some limitations on throughput (particularly for e-beam lithography). In recognition of these limitations, a second category of "dry" cleanroom-free methods has been developed, including 3D printing, [8][9][10] laser machining, [11] and "pick-and-place" technologies. [12,13] These techniques are useful, but they also rely on expensive and specialized tools and well-trained personnel, and can have limited throughput.A third category of "wet" cleanroom-free techniques has recently been proposed for forming topographical micropatterns, relying on dielectrophoresis tweezers (DEPT), [14][15][16] acoustic tweezers (AT), [17][18][19] magnetic tweezers (MT), [20,21] and optical tweezers (OT). [22][23][24][25] These techniques, in which patterns of 3D particles are assembled in a fluidic environment and are later dried for use in TMP applications, are creative and interesting, and preserve many of the advantages of the canonical methods while allowing for accessible, cleanroom-free operation. But each of the individual techniques has disadvantages; for example, DEPT and AT require the manufacture of micropatterned electrodes (typically using canonical cleanroom methods) and lack the flexibility to pattern large numbers of features. Likewise, MT-based methods can only assemble micro-objects that respond to magnetic fields, and OT-based techniques have sub-nanoNewton (
The microtubes made through rolling-up of strain-engineered nanomembranes have received growing research attention after their first invention due to the technology's high flexibility, integrability, and versatility. These rolled-up microtubes have been used for a variety of device applications including sensors, batteries and transistors, among others. This paper reports the development of highly sensitive whispering-gallery mode (WGM) chemical sensors based on rolled-up microtube optical microcavities (RUM-OCs). For the first time, such microcavities were batch fabricated through rolling-up of plasma-enhanced chemical vapor deposition (PECVD)-synthesized SiO /SiN bilayer nanomembranes, which have better optical properties than the conventional electron-beam-deposited SiO/SiO bilayers. Benefiting from the high refractive index (RI) of PECVD-deposited SiN , our RUM-OC shows an enhanced quality factor of 880 that is much higher than that (50) of a SiO/SiO RUM-OC with the same dimensions. The developed RUM-OC is used for sensitive WGM solvent sensing, and demonstrate a limit of detection of 10 refractive index unit (RIU), which is 10 times lower than that (10 RIU) of a SiO/SiO RUM-OC.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.