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Two-dimensional plasmonic biosensing platform: Cellular activity detection under laser stimulation
摘要： Combining biosensors with nanoscience provides great advantages such as being label-free and real time, highly sensitive, and small in size, as well as providing a low limit of detection and integration to other systems. That is why plasmonics finds various applications in drug detection, food safety, agriculture, photothermal therapy, etc. In this paper, we have fabricated a two-dimensional plasmonic grating biosensor using a soft lithography technique, which has eliminated some disadvantages of conventional plasmonic structures like expensive fabrication cost, inflexibility, and lack of mass production. On the other hand, we benefited from infrared neural stimulation for regulating membrane depolarization, which was based on photothermal mechanism and provided a contact-free and high spatial/temporal resolution. Eventually, the membrane depolarization of two different cell types of Hep G2 and mesenchymal stem cells cultured on two-dimensional plasmonic structure has been investigated under infrared neural stimulation. After preparing the soft plasmonic crystal, its reflection spectra and respective ellipsometry parameters were analyzed before and after cell culture with/without stimulation (near-infrared immune region ～1450 nm). By comparing the obtained ellipsometry results for HEP G2 and mesenchymal stem cells, it is observed that the behavior of two cell types with respect to IR stimulation was the same as well as providing us the possibility of distinguishing the level of membrane depolarization under various stimulating frequencies. The strength of this integrated system for membrane depolarization detection has been shown experimentally, which can open new avenues toward neuroplasmonic application in the future.
关键词： infrared neural stimulation,membrane depolarization,ellipsometry,soft lithography,plasmonic biosensor
更新于2025-09-11 14:15:04
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Nano- and Microfabrication for Industrial and Biomedical Applications || Basic technologies for microsystems
摘要： This chapter introduces the reader the processes used to manufacture microelectronics. A silicon wafer is coated with a resist, most usually by wet deposition. Vapor deposition is also used, but high vacuum conditions are needed. The resist is a photosensitive polymer, which either cross-links or is destroyed under ultra violet (UV) light. Photolithography illuminates this resist through a pattern. The pattern is designed by computer-aided design (CAD), and copied onto a mask of borosilicate. Silicon is machined by wet chemical etching (which has precision limitations, but relatively low cost), or dry etching processes, in which its surface is bombarded with ions. Alternatively, the Bosch process uses gasses heated under low pressure to a plasma state to etch the surface. A great deal of research is under way to investigate other techniques and materials for use in microsystems. Examples include the use of powder blasting and laser ablation as etching techniques, and single-crystal (SC) quartz, amorphous glass, and thermoplastic polymers as alternatives to silicon. Thick resist lithography and locally controlled photopolymerization are techniques that could be used to create microscale features in these polymers. Since recent developments in industrial, biological, and biomedical applications particularly embrace replication technology as a means to pattern multiple parts from a master pattern or even use it for stamping biomolecular features onto a surface for the design and development of novel biological assays, it is time to introduce soft-lithography among the basic microsystems technologies together with a set of nanolithographies presented in Chapter 4.
关键词： soft-lithography,silicon micromachining,thin films,microsystems,nanolithography,photolithography
更新于2025-09-09 09:28:46
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Reference Module in Materials Science and Materials Engineering || Sub-Micrometer Patterning Using Soft Lithography
摘要： The development of lithographic techniques that allow for controlling material properties at sub-micrometer length scales has become central to progress in many scientific and technological areas. In microelectronics, for example, optical lithography has enabled high-volume manufacturing of integrated circuits at ever-increasing density, complexity, and performance. This evolution has become possible in part through incremental changes toward shorter radiation wavelengths, high-index lens materials, advanced projection systems, and optimized resist formulations, pushing back the limits in resolution set by optical diffraction. By using current state-of-the-art step-and-repeat exposure tools it is possible, for example, to achieve a minimum transistor gate length of 20 nm and a dynamic random access memory periodicity (half-pitch) of 50 nm. Scanning beams of high-energy particles comprising atoms, ions, and electrons have also evolved into robust and mature technologies, which are being used for micro- and nanofabrication purposes. Each of these techniques can create arbitrary features at very high resolution (eg, 5 nm and below), but their serial nature limits the scope of applications to selected, low-volume fabrication tasks. Many of these techniques relies on complex and expensive equipment, making them unpractical for research in common laboratory environments. Moreover, they are not well suited for applications in a number of emerging fields, such as biotechnology or plastic electronics, where sensitive materials being incompatible with resist and development procedures, curved or uneven substrates, and large-areas are of primary concern.
关键词： replica molding,Soft lithography,sub-micrometer patterning,microcontact printing,edge-spreading lithography
更新于2025-09-04 15:30:14