To the uninitiated, the phrase “optical microelectromechanical systems”or optical MEMS must appear to refer to a field of incredible specialization. Ironically, the number of disciplines involved, optics, mechanics, and electronics, make the field most accessible to scientists of great technical breadth. This is especially true when optical MEMS is used in chemical and biological applications - the theme of this text. Underlying all of them is the technology of microfabrication. One chapter could not possibly cover all of the techniques developed over the decades for very-large-scale integration (VLSI) and general MEMS systems. Indeed there are entire textbooks devoted specifically to both types. In this chapter then, we present the characteristics of fabrication and design that are specific to bring optics into the system. In particular, there are a number of materials and fabrication techniques that are specific to optical MEMS systems. When dealing with light, one may have to handle visible, ultraviolet, or infrared portions of the spectrum, each of which has its own special set of optimal substances. Since one often has to emit light or detect it in special wavelength regions, semiconductors other than silicon often must be incorporated, each with their own set of wet and dry chemical etching techniques and their own set of mechanical properties. Standard mechanical characteristics that play no role in “normal”MEMS systems may prove problematic in optical MEMS. For example small size may lead to diffraction, typical surface roughness may limit optical cavity resolution, and mechanical or motion may deform mirrors to limit the number of resolvable spots. Even thermal noise may place limits on optical design. Each of these topics is covered in the pages that follow. For the reader who is interested in further exploring many of these areas, we recommend the text by Solgaard.

This Chapter discussed the following: brief history of electrowetting; surface tension; contact angle; liquid lens focal length; tunable liquid microlens; electrowetting-based microlens on a flexible curvilinear surface; arrayed electrowetting prism and switchable microlens; electrowetting-controlled liquid mirror; electrowetting-driven optical switch and aperture; electrowetting display.

Mining smartness from vision organs found in nature becomes of much interest in optical applications such as imaging, display, or lighting. Unlike conventional bulk optics, miscellaneous hierarchical structures at micro- or nanoscale deliver highly efficient light management with a small form factor. For example, natural species have evolved their eyes to obtain all necessary visual information from surrounding environment. Natural imaging schemes can be chiefly classified by three different types of pinholes, camera, and compound eyes. Pinhole eyes found in clam are sensitive enough to allow the animals to protect themselves from dangerous environment but not so sensitive to collect all visual inputs. Unlike other types, the pinhole eye as one of natural eyes with the simplest and thinnest optical configurations is well known for infinite depth-of-field, i.e., no blurred imaging depending on object distance and thus these unique features have been implemented on early-stage simple camera imaging systems. Besides, advanced pinhole eyes are also found in viper snakes of Crotalinae and some python of Boidae, which combine both pinhole eye and ordinary camera eye in order to confer infrared (IR) as well as visible imaging for warm-blooded preys. Compound eyes found in arthropods exhibit many intriguing features for wide field-of-view (FOV), fast motion detection, polarization sensing, color imaging, or high-resolution imaging with compact optical configuration unlike other types. They comprise arrays of integrated optical units called ommatidia. The individual component consists of a facet lens, a crystalline cone, a light-guiding rhabdom, and photoreceptor cells. Furthermore, nature exhibits ten different optical schemes of compound eyes, which have some attractive figures-of-merits for sustainable life style in visual acuity, photon collection efficiency, and polarization or spectral sensitivity. Such biological inspiration recently and actively provides new opportunities for improving optical capability of conventional imaging systems by incorporating nano- and microfabrication methods and furthermore it delivers technical solutions for miniaturized optical systems in medical, industrial, and military fields. In this chapter, we will review engineering approach inspired from diverse biological organs, which can be utilized for miniaturized optical systems in diverse optical applications.

The use of QDs allows for hyperspectral imaging of biosamples with a simple microscope configuration. In addition, proper choice of different gold nanoparticles, such as nanorods and nanospheres, enables absorption-based analysis of multiple biomarkers. Combination of QDs and gold nanoparticles provides a potential on-chip hyperspectral imaging tool for multi-biomarkers recognition at cellular level. In addition to microscopy, QD light sources can be used for several types of absorption spectroscopy techniques, such as pulse oximetry [90] or tissue spectroscopy [91], where the absorption spectra are correlated with physical characteristics. A possible application area beyond biomedical applications is the use as an illumination source alternative to conventional RGB-LEDs. Conventional RGB color spaces, such as sRGB or Adobe RGB, cover only a portion of visible colors [92], while our light source can simulate any spectrum expressed as linear combinations of multiple QD emission peaks. The QD light source can be a strong illumination tool for medical and industrial imaging.

This chapter will first cover the use of optical gradient forces for the trapping of cells and other biological objects. This method is also widely known as optical tweezers (OT). Other types of direct optical manipulation will be discussed, such as optical cell sorters and optically driven fluids, droplets, and bubbles. Indirect optical manipulation via optically induced electrokinetic forces will be reviewed, in particular, optically induced dielectrophoresis (ODEP). The chapter will also discuss the use of optical manipulation for cell poration, lysis, and surgery. The chapter will finish with a brief discussion of future directions in this field.

In this chapter, the fabrication, characterization, and applications of the NAO, one of the most widely used nanostructures, the NAO thin film and the NAO micropatterns on glass substrates have been covered. Specifically, the fabrication processes of the NAO thin film at a wafer scale and the NAO micropatterns on the glass substrate have been described in detail. The optical properties such as the optical interference and optical emission of the NAO thin film and micropatterns have also been evaluated, which offers essentially the same quality of those from the NAO fabricated directly from an Al plate or foil. In addition, the fluorescence enhancement capability of the NAO and the possible physical mechanisms behind the enhancement capability have been discussed in detail. The optical blue emission of the NAO micropatterns can facilitate the determination of the level of the anodization of the Al micropatterns, while the optical interference signal from and fluorescence enhancement of the NAO micropatterns can be exploited for a variety of biosensing applications.