Microfluidic sensor array

In addition, an array of nested wells with microfluidic cormection has been developed for protein expression. The array device consists of reaction chambers nested in corresponding feeding chambers. A dialysis membrane and a microfluidic channel are used to connect reaction and feeding chambers. We demonstrate higher expression yield of GFP, CAT, and luciferase in the device than in a conventional microcentrifuge tube. The microfluidic sensor array is also demonstrated for detecting ricin from 0.035 to 0.69 nM.with a detection limit at 10 pM. 

Recent developments in sensor technology allow to create different integrated and miniaturized sensor arrays. Using microsystemtechnology fluidics can be added creating whole micro-analytical devices on chip. However, there are drawbacks involving inappropriate sensor function in media and production. Using sophisticated sensor construction and microfluidics such drawbacks can be overcome. In this chapter different sensor systems and whole micro-analytical devices are presented with emphasis on their applications. 

Keywords Integrated miniaturized sensor arrays, microfluidics, biosensors, microelectronic, microsystemtechnology. 

A good example for a microanalytical device is the gas sensor array. The conductometric approach for gas sensing was favored during the last years using metal oxides or conductive polymers. Unfortunately such sensors are quite unspecific and therefore sensor arrays with modified sensing layers have to be used. The selectivity derives from a sophisticated data processing using neural networks. Complete gas analysis systems with microfluidic and data acquisition are now under development. 

In conclusion, the advantages of microfluidic devices, parallel synthesis, and combinatorial approaches can be merged to integrate a fluorescent chemical sensor array in a microfluidic chip. Fluorescent microchannel array can be produced by parallel synthesis of fluorescent monolayers covalent attached to the walls of glass microchannels. 

Basabe-Desmonts, L. Benito-Lopez, F. Gardeniers, H. J. G. E. Duwel, R. van den Berg, A. Reinhoudt, D. N. Crego-Calama, M. Fluorescent Sensor Array in a Microfluidic Chip. Anal. Bioanal. Chem. 2008, 390, 307-315... 

Crego-Calama et al. reported on the construction of a new type of sensor array based on a microfluidic chip (Fig. 12) [57]. This technique has recently been developed and exploited in broad analytical applications [58] and clinical diagnostics [59], as it provides convenient small platforms, and usually requires small sample volumes, in a continuous flow, for real-time measurements. In particular the authors developed a microfluidic chip, with the microchannel walls combinatorial-based functionalised by SAMs of five fluorescence-responsive receptors, as sche-... 

Basabe-Desmonts L, Benito-Lopez F, Gardeniers HJGE, Duwel R, van den Berg A, Reinhoudt DN, Crego-Calama M (2008) Fluorescent sensor array in microfluidic chip. Anal Bioanal Chem 390 307-315... 

Fig. 21.7 Device pictures (a) the entire chip including the sensor array and the microfluidic channels, (b) the magnified picture of the 3-electrode sensor, and (c) the customized detection circuits along with the chip. From (113) reproduced by permission of Elsevier...

Holden, M.A., Kumar, S., Castellana, E.T., Beskok, A., Cremer, P.S., Generating fixed concentration arrays in a microfluidic device. Sensors Actuators B 2003, 92, 199-207. 

Adams, M.L., Enzelberger, M., Quake, S., Scherer, A., Microfluidic integration on detector arrays for absorption and fluorescence micro-spectrometers Sensors... 

Fig. 12 Lab-on-chip integration and application of arrays of nanohole arrays (a) Schematic of device at range of relevant lengthscales (b) Schematic of optical and fluidic setup with an image of the device (c) Image showing six cross-stream nanohole sensors across a cross-stream microfluidic concentration gradient and (d) Results of on-chip biosensing test. Reprinted with permission from the American Chemical Society [67]...

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