Friday, September 25, 2009

Better imaging with Optofluidics

What is Optofluidics ?

Optofluidics refers to manipulation of light using fluids, or vice-verse, on the micro to nano meter scale. Optical devices which incorporate liquids as a fundamental part of the structure can be traced at least as far back as the eighteenth century when rotating pools of mercury were proposed as a simple technique to create smooth mirrors for use in reflecting telescopes. The field of optofluidics is a “marriage” of nano-photonics and micro-fluidics! The introduction of liquids in the optical structure enables flexible fine-tuning and even reconfiguration of circuits such that they may perform tasks optimally in a changing environment.This allows for enhanced optical detection in lab-on-a-chip systems with a potentially strong impact on bio-technology, life-sciences, and bio-medical/health-care industries.It is used in a broad spectrum of military and civilian applications for imaging, spectroscopy, communications,  sensing, and displays.

The technology has now allowed the introduction of an inexpensive and high-resolution microscope that has been engineered to fit onto a single chip (See Optofluidic microscope shrinks to fit on a chip.) The performance of the device is comparable to a 20x microscope, but in terms of size, cost and ability to mass produce, the device has significant advantages.

  • The lack of optical elements in the arrangement implies that there are no aberrations to worry about. 

  • This is an intrinsically space-conserving method. 
  • The entire chip is illuminated from above; no light source needed sunlight is sufficient.

This portable and cheap device is particularly appealing for third-world applications where it could be used in the field to analyse blood samples for malaria or check water supplies for pathogens. In the future, the microscope chips could be incorporated into devices that are implanted into the human body. Pretty good.

An on-chip implementation of the optofluidic microscope.

In the set-up, a voltage of 25 V is applied across the inlet and outlet of a microfluidic channel that is 2.4 mm long, 40 µm wide and 13 µm high. The electric field draws the specimen across the aperture array in a steady stream. The array consists of 120 holes with a diameter of 0.5 µm and separation of 10.4 µm, fabricated on a 2D CMOS imaging sensor. The sensor comprises a grid lattice of 1280 x 1024 square pixels with a pixel size of 5.2 µm.

Also see - Developing optofluidic technology through the fusion of microfluidics and optics

Being a very exciting field with a plethora of potential applications, its no wonder that hundreds of high-tech companies are working to optimize the technology. Heres a list of microfluidics research groups

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