Chip measurement system

Challenges remain in the development of lab-on-a-chip sensing systems. The overall lifetime of a sensor chip is always determined by the sensor with the shortest lifetime, which in most cases is the depletion of reference electrolytes. Measures to minimize cross-talking among sensors, especially when biosensors are integrated in the system, also should be implemented [122], The development of compatible deposition methods of various polymeric membranes on the same chip is another key step in the realization of multisensing devices. 

Until now, all in the literature proposed LAPS devices are complete autarkic measurement systems. Further applications can be found by the integration of LAPS devices into existing analytic fields. This requires the development of inexpensive integrated electronic units to operate the LAPS and to provide a standardised communication with higher process levels. The LAPS devices need to be easy in use to allow the operation in commercial environments. Due to the simple structure of the LAPS, the integration into micro-electro-mechanical systems (MEMS), lab-on-chip and micro-total analysis systems (p-TAS) might be of special interest in the near future. 

Significant advances have occurred during the past decade to miniaturize the size of the measurement system in order to make online analysis economically feasible and to reduce the time delays that often are present in analyzers. Recently, chemical sensors have been placed on microchips, even those requiring multiple physical, chemical, and biochemical steps (such as electrophoresis) in the analysis. This device has been called lab-on-a-chip. The measurements of chemical composition can be direct or indirect, the latter case referring to applications where some property of the process stream is measured (such as refractive index) and then related to composition of a particular component. 

An optical absorbance measurement system is also integrated to form a lab-on-a-chip. 

Conventional chromatographic or capillary electrophoretic devices are based on analyte detection by absorbance, for example, of ultraviolet (UV) light. However, in chip-based systems absorbance measurements are the exception as detection cells have to be developed leading to an extension of the path-length of the transmitted fight. 

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