Fitting Components onto a Chip

Due to the compactness of LOC systems, extensive integration of functionality and the small volumes involved, many parts must now be made available in a miniaturised form. Hence there are many components and tools to aid the fitting together of all the components onto such a small platform. These include  

Optical fibres with selective reagents immobilised onto the tips can also be used as optical probes (optodes) that are physically dipped into a liquid sample or brought into 

Superluminescent LEDs (SLEDs) are LEDs pumped at high current so that stimulated emission occurs. These miniature light sources are approximately 1000 times brighter than a tungsten-halogen light bulb. 

Developments in the field of LEDs are occurring all the time. There are new white organic LEDs, new green polymer LEDs and new blue polymer LEDs. Ashwell et al. are developing molecular diodes from a bilayer of electron-rich and electron-poor molecules.  

Photodiodes are similar to LEDs but with reversed bias. They are semiconductor devices that, instead of emitting radiation, absorb UV, visible or IR light and register this as a change in electrical signal. These tiny detectors fit easily into an electrical circuit. An avalanche photodiode allows the normally small signal to be multiplied enabling better detection limits. 

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Section IV then tackles the most recent trend in analytical instrumentation, which is miniaturisation and the drive to create lab-on-a-chip devices. In this section, 1 discuss the development of chip-based technologies and the challenges associated with this such as pumping fluids on the microscale, fitting components onto a chip, detection strategies and how processes such as mixing are so different in the microworld when compared to the macroworld. 

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