Page 233 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

232 CHAPTER 9 Application of microfluidics in cancer treatment

input voltage, beads washing with a high recovery rate (>98%) and high washing
efficiency (>97%) have been done. Preparation of WBCs from whole blood through
RBC lysis is widely employed in immunology and clinical diagnosis [46,47] and
purification of white blood cells (WBCs) from lysed blood samples is investigated.
By connecting polydimethylsiloxane (PDMS) microchannel to a piezoelectric
substrate, SSAW-based cell/bead washing device is made. A pair of IDTs is placed
on both sides of the microchannel. SAWs are generated from both IDTs when a radio
frequency (RF) signal is applied to IDTs. The SAWs diffuse in opposite directions
on the substrate surface and leak into microchannel containing liquid. A SSAW field
is organized due to the interference between them that causes pressure fluctuations
in the liquid. As a result, a periodic distribution of pressure nodes and pressure anti-
nodes is formed inside the microchannel. The ARF and Stokes drag force are exerted
to particles flowing into the SSAW field.
Due to the competition of the acoustic radiation and Stokes drag forces, the cells
or beads flowing into the SSAW field will deviate from their original medium stream.
Thus, cells/beads can be washed out from the original medium and collected through
the outlet. The different microfluidics based single-cell analysis including cellular
analysis, single-cell manipulation, genetic analysis, protein analysis, and single-cell
analysis using flow cytometry have been investigated [48]. All of these procedures
have some advantages and disadvantages and can be combined according to device
application in order to device performance improvement.
The use of microfluidic technology has many advantages as follow:

1. capability to analyze single molecules such as proteins, DNA, and eventually
to single cells [4].
2. capacity for high-throughput screening.
3. precise control of flow due to the presence of microfluidic channels which
allows the study of many important biomechanical processes such as shear
stress [21].
4. high efficiency.
5. potential to achieve higher sensitivities.
6. capability to process extremely low volumes of samples and reagents, which
significantly reduce the cost of assays and this is particularly important in
the case of irradiated patient samples which are precious as the collection is
usually difficult.
7. the fast analytical times.
8. portability for point-of-care applications.
9. enabling excellent spatial control of cell distribution at physiological length
scales.
10. ability to control the local cellular microenvironment precisely, without
(or with less) interference from the external environment that causes better
monitoring of cellular behavior.
11. facilitating high parallelization of experiments.
12. less contamination.