HALDIA INSTITUTE OF TECHNOLOGY

Lab on a Chip technology

Submitted by:-

SANJIB PASHI

APPLIED ELECTRONICS AND INSTRUMENTATION ENGG.

Acknowledgement

I am sincerely thankful to Mr.Monodipan Shaoo& Mr.Soumya Roy- Faculty of AEIE Dept. for this report. I thank them for their total support & UNENDING help to me during the entire report. I am also thankful to our friends who have helped me very much during the report for any kind of information, data, format, etc. Last but not the least; i am thankful to our college & its library for providing me the needful and supporting material for my report.

CONTENTS:

Introduction What is LOC? Chip materials & fabrication technology Electronic circuitry on lab-on-chips Role of Nanotechnology Advantages Disadvantages Application Conclusion

INTRODUCTION

• Lab-on-a-chip refers to technologies which allow operations which normally require a laboratory synthesis and analysis of chemicals on a very miniaturized scale, within a portable or handheld device.

• A typical lab-on-chip device contains micro channels, which allow liquid samples to flow inside the chip, but also integrates measuring, sensing and actuating components.

What is LOC? A lab-on-a-chip (LOC) is a device that integrates one

or several laboratory functions on a single chip of only millimeters to a few square centimeters in size. LOCs deal with the handling of extremely small fluid volumes down to less than pico liters. Lab-on-a-chip devices are a subset of MEMS devices and often indicated by "Micro Total Analysis Systems" (µTAS) as well. LOC is closely related to, and overlaps with, microfluidics which describes primarily the physics, the manipulation and study of minute amounts of fluids. However, strictly regarded "Lab-on-a-Chip" indicates generally the scaling of single or multiple lab processes down to chip-format, whereas "µTAS" is dedicated to the integration of the total sequence of lab processes to perform chemical analysis. The term "Lab-on-a-Chip" was introduced later on when it turned out that µTAS technologies were more widely applicable than only for analysis purposes.

Chip materials & fabrication technology: The basis for most LOC fabrication processes

is photolithography. Initially most processes were in silicon, as these well-developed technologies were directly derived fromsemiconductor fabrication. Because of demands for e.g. specific optical characteristics, bio- or chemical compatibility, lower production costs and faster prototyping, new processes have been developed such as glass, ceramics and metal etching, deposition and bonding, polydimethylsiloxane (PDMS) processing (e.g., soft lithography), thick-film- and stereolithography as well as fast replication methods via electroplating, injection molding and embossing. Furthermore the LOC field more and more exceeds the borders between lithography-based microsystem technology, nanotechnology and precision engineering.

FABRICATION PROCESS: Lab-on-chip fabrication techniques are

analogous to those of microelectronics, since closely related micro fabrication and integration methodologies are shared by both.

There are 3 way of fabrication process:- Deposition method Etching process Bonding

DEPOSITION METHOD: Here we can use any vapour deposition process that

produces thin metal, ceramic, or compound films, through thermal oxidation in a gas chamber at an elevated temperature. (a)Metallization of the substrate by sputtering a metal film of Au, Pt, or ITO.(b) Spin coating of photosensitive resist film onto the metal film.

Etching process: In lab-on-chip fabrication technology,

patterning is the transfer of outlines of features (which define micro channels, microelectrodes, or other components) on the top of a substrate by means of ultraviolet illumination via a photo mask.(c) exposure of the photosensitive film via a photo mask that results in the transfer of the desired electrode patterns onto the photosensitive film.(d) after photo-development, chemical etching removes the bare metalized areas, which results in the formation of the electrodes.

Bonding : After patterning all features on

substrates (micro channels, elements, inlets, etc), the base plate and the cover plate must be bonded in order to seal the chip. It is possible to bond silicon, glass, or rigid polymer plates, by bonding

Bond the PDMS channel to a glass substrate

Electronic circuitry on lab-on-chips :

The sensor is followed by an analogue front-end, which conditions the measuring signal, analogue-to digital converters (ADC), and a digital signal processor that analyses the signal.

The signals can be electrical, optical, etc.

The analyzed data further sent via a bus to external computer for post-processing, or even visualized on integrated displays or external screen.

Role of Nanotechnology: Nanosensors are also a key element of

many lab-on-a-chip systems. Sensors have been developed using nano materials like carbon nano tubes, capable of detecting very low concentrations, even down to single molecules in some cases. These are extremely useful in allowing a high degree of analytical flexibility in a lab-on-a-chip system without increasing the overall size of the device.

Advantages: LOCs may provide advantages, which are specific to

their application. Typical advantages are:

low fluid volumes consumption (less waste, lower reagents costs and less required sample volumes for diagnostics)

faster analysis and response times due to short diffusion distances, fast heating, high surface to volume ratios, small heat capacities.

better process control because of a faster response of the system (e.g. thermal control for exothermic chemical reactions)

compactness of the systems due to integration of much functionality and small volumes

massive parallelization due to compactness, which allows high-throughput analysis

lower fabrication costs, allowing cost-effective disposable chips, fabricated in mass production

part quality may be verified automatically safer platform for chemical, radioactive or biological studies because of integration of functionality, smaller fluid volumes and stored energies

Disadvantages: Some of the disadvantages of LOCs are:

novel technology and therefore not yet fully developed physical and chemical effects—like capillary forces,

surface roughness, chemical interactions of construction materials on reaction processes—become more dominant on small-scale. This can sometimes make processes in LOCs more complex than in conventional lab equipment

detection principles may not always scale down in a positive way, leading to low signal-to-noise ratios

although the absolute geometric accuracies and precision in microfabrication are high, they are often rather poor in a relative way, compared to precision engineering for instance.

APPLICATION: Personalised medicine Point-of-care diagnostics Marine sensors Monitor pollution Monitor pandemics / diseases Link to medical and patient databases Usage as terminal testers Military medicine

CONCLUSION

• Future advancements in lab-on-a-chip technology will always depend on at least two major scientific disciplines - microfluidics, and molecular biology. Nanotechnology will play a key role in tying these two fields together as the technology progresses.

• Despite the hurdles always associated with commercialization of a new technology, viable examples of these devices are beginning to appear on the market. It seems that lab-on-a-chip technology will become increasingly important in the coming years, both in the medical world and in the chemical industry.

References

1. S.C.Terry, J.H.Jerman and J.B.Angell:A Gas Chromatographic Air Analyzer Fabricated on a Silicon Wafer,IEEE Trans.Electron Devices,ED-26,12(1979)1880–1886.

2. A.Manz, N.Graber and H.M.Widmer:Miniaturized total Chemical Analysis systems:A Novel Concept for Chemical Sensing,Sensors and Actuators,B 1 (1990)244–248.

3. Venkat Chokkalingam, Jurjen Tel, Florian Wimmers, Xin Liu, Sergey Semenov, Julian Thiele, Carl G. Figdor, Wilhelm T.S. Huck, Probing cellular heterogeneity in cytokine-secreting immune cells using droplet-based microfluidics, Lab on a Chip, 13, 4740-4744, 2013, doi:10.1039/C3LC50945A http://pubs.rsc.org/en/content/articleland ing/2013/lc/c3lc50945a#!divAbstract

4. Kirby, B.J. (2010). Micro- and Nanoscale Fluid Mechanics: Transport in Microfluidic Devices. Cambridge University Press. ISBN 978-0-521-11903-0.

5. Bruus, H. (2007). Theoretical Microfluidics.6. Karniadakis, G.M., Beskok, A., Aluru, N. (2005). Microflows and

Nanoflows. Springer Verlag.7. Tabeling, P. Introduction to Microfluidic.8. Berthier, J. and Silberzan, P. Microfluidics for Biotechnology.