## 6 Conclusion  
Figure 2: Instrument 1: Label-free Biomolecular Interaction Detection (BIND) Scanner utilizing a PC surface biosensor. (**A**) Schematic of excitation/detection instrument where an imaging spectrometer gathers hundreds of reflected spectra simultaneously from one line across the sensor surface; (**B**) PWS images of Protein A (bright regions represent regions of greater PWS) gathered on a 6-mm diameter region of a PC biosensor, which is imaged at approximately 20 μm pixel resolution after writing the letters ‘NSG’ (Nano Sensors Group) with a microarray spotting tool (PerkinElmer, Inc. PiezoarrayTM) (Reprinted in part with permission from [50], © 2006 Future Drugs Ltd.); (**C**) PWS images with shift scale bars (\(\Delta\)PWV) indicating the magnitude of wavelength shifts in nanometers. Pixels with higher PWS displayed in brighter colors indicate locations where Panc-1 cell attachment has occurred. The three columns of image sets represent the following: (a) untreated control, (b) extract that induced 100% cell death Petunia punctata Paxton (_P. punctate_), (c) extract that enhanced proliferation Anisoptera glabra Kurz (_A. glabra_). The top row of images was taken before exposure and the bottom row of images was taken after the 24 h exposure period with a plant extract at 100 μm/mL. Scale bar (white) = 300 μm (Reprinted in part with permission from [41], © 2010 BioMed Central Ltd.). ## 6 Conclusion  
Figure 3: Instrument 2: Transmission acquisition mode of photonic crystal biosensor integrated with an upright imaging microscope and using laser as light source. **(A)** Schematic of combined label-free and enhanced-fluorescence imaging instrument; **(B)** Enhanced (a) fluorescence and (b) label-free images of 50 mg/mL SA-Cy5 spots on a PC biosensor. Inverted transmission _versus_ angle response for a pixel inside and outside the SA-Cy5 spot in (c), and cross-section of the label-free image through two SA-Cy5 spots in (d). Rather than measuring the PWS, the label-free imaging system measures the angle of minimum transmission (AMT) by illuminating the PC sensor at a fixed wavelength while scanning the angle of illumination through computer-controlled rotation of the mirror (reprinted in part with permission from [76], © 2009 American Optical Society); **(C)** Label-free image of a DNA microarray measured with a PC biosensor. The white dashed box denotes the location of a set of 20 intentional blank spots. A line profile running through a row containing 4 blank spots followed by 12 probe spots is shown in **(D)** (Reprinted in part with permission from [37], © 2010 American Chemical Society). The advantages of PCEM are inherent from the optical properties of slab-based PC surfaces, since they can be designed as a wavelength-selective optical resonator and functionalized as a sensitive optical transducer. For instance, high spatial resolution (in-plane) can be achieved in bioimaging due to the restricted lateral propagation of electromagnetic waves on surface of the PC slab. Enhanced electromagnetic fields (in the form of an evanescent field) near the PC surface (penetration depth of ~200 nm) only illuminate surface-adsorbed biomaterials, such as the extracellular matrix (ECM), membrane components of surface-adsorbed cells, or cellular surface-attached nanoparticle tags. This near-field high-intensity illumination regime promises a high axial resolution (out-of-plane) of ~200 nm, which is beyond the diffraction limit in the spectrum-range of the visible light (400-700 nm) during bioimaging. Compared to the broadband resonances and lossy modes (due to absorption) on metal surfaces, narrow line width (e.g., a few nm) resonant spectra and high reflection efficiency (e.g.,  
Figure 4: Instrument 3: Reflection acquisition mode of photonic crystal biosensor integrated with an inverted microscope and using LED as light source.