Circulating Tumor Cells Analysis

Isolation of circulating tumor cells (CTCs) hold great significance in clinical prognosis and biomedical research. DEP-activated cell sorting especially those device exploiting the 3D electrode has drawn extensive attention without extinct labeling. Here we overcome challenges posed by the 3D electrode in prior art and leverages DEP through a uniquely elegant 3D design with a simple fabrication process. Highly effective isolation of human colorectal cancer cells from lymphocytes with high loading density and low activation voltages have been achieved.

References

  1. Xiaoxing Xing, Randy Y. C. Poon, Cesar S. C. Wong, and Levent Yobas, “Label-free enumeration of colorectal cancer cells from lymphocytes performed at a high cell loading density by using interdigitated ring array microelectrodes”, Biosensors and Bioelectronics, vol.61, pp.434-442, 2014.
  2. Xiaoxing Xing, Mengying Zhang, and Levent Yobas, “Interdigitated 3-D Silicon Ring Microelectrodes for DEP-Based Particle Manipulation”, JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, vol.22, pp.363-371, 2013.

Highly scalable nanofluidic electronic devices for biomolecule detection and analysis

Nanofluidic electronics is likely to deliver a new class of devices, which could offer new capabilities besides the increased speed, resolution, and sensitivity in the analysis of biomolecules. We have developed advanced nanofluidic platforms including integrated nanocapillaries, glass nanopipettes, and integrated asymmetric nanoslits. We have also developed new biosensing techniques and novel integrated ionic current diode devices, which enable various biomolecular applications such as DNA stretching, DNA quantification, and femtomolar biomarker protein detection.

References

  1. Yifan Liu and Levent Yobas, “Label-free specific detection of femtomolar cardiac troponin using an integrated nanoslit array fluidic diode,” Nano Letters, vol. 14, no. 12, pp. 6983-6990, 2014.
  2. Yifan Liu and Levent Yobas, “Self-sealed cylindrical nanocapillaries fabricated with coarse (>1 μm) lithography,” Biomicrofluidics, vol. 6, no. 4, 2012.
  3. Yifan Liu and Levent Yobas, “Label-free electrical quantification of amplified nucleic acids through nanofluidic diodes,” Biosensors and Bioelectronics, vol. 50, pp. 78-83, 2013.

Nanofluidics for Biomoleucle Separation

Gel electrophoresis has long been used in biomolecule separation. However, conventional sieving matrix encounter many drawbacks. Stimulated by this, we develop a novel sieving matrix, so called capillary-well motif, based on a semiconductor fabrication process that does not require advanced to precisely define the confining spaces. We study biomolecule separation and DNA behavior in this capillaries. Another molecular separation technique is liquid chromatography. We are capable of performing open tubular chromatography (OTC) with integrated nanocapillaries and successfully separated several types of biomolecules.

References

  1. Lian Duan, Zhen Cao and Levent Yobas, “Pressure Driven Liquid Chromatography in Self-enclosed Glass Microcapillaries Integrated on Silicon ”, MEMS, pp. 780 - 783, 2016.
  2. Zhen Cao and Levent Yobas, “Gel-Free Electrophoresis of DNA and Proteins on Chips Featuring a 70 nm Capillary–Well Motif”, ACS Nano, vol.86, DOI: 10.1021/nn505605e, 2014.
  3. Zhen Cao and Levent Yobas, “Fast DNA Sieving through Submicrometer Cylindrical Glass Capillary Matrix”, Analytical Chemistry, vol.86, pp.737-743, 2014.

Ag Nanorods for SERS in Microfludics

We modified OAD process such that it can be implemented in a standard tool with the substrate on a leveled stage. Morphology of the Ag nanorods and their SERS spectroscopy are studied.

References

  1. Mengying Zhang, Zhen Cao and Levent Yobas, “Microchannel plate (MCP) functionalized with Ag nanorods as a high-porosity stable SERS active membrane,” Sensors and Actuators B, vol. 184, no. 31, pp. 235-242, 2013.
  2. Junxue Fu, Zhen Cao, and Levent Yobas, “Localized oblique-angle deposition: Ag nanorods on microstructured surfaces and their SERS characteristics”, Nanotechnology, vol. 50, no. 22, 505302, 2011.

Silicon/PDMS microcapillary platforms for cell/particle manipulation and analysis

We developed silicon/PDMS based microcapillary platforms for cell/particle manipulation, analysis and treatment. Implementation of efficient particle capturing, cellular impedance spectrum and electroporation has been successfully accomplished, demonstrating the versatile functionalities of our platforms

References

  1. Y. Luo, and L. Yobas, “Forces acting on a particle in a concentration gradient under an externally applied AC electric field”, accepted, Applied Physics Letters.
  2. Y. Luo, and L. Yobas, “Flow-through electroporation of mammalian cells in decoupled flow streams using microcapillaries”, Biomicrofluidics, vol. 8, p. 052101, 2014.
  3. F. Zeng*, Y. Luo*, L. Yobas, and M. Wong, “Self-formed cylindrical microcapillaries through surface migration of silicon and their application to single-cell analysis,” Journal of Micromechanics and Microengineering, vol. 23, p. 055001, 2013. (* equal contribution)
  4. Y. Luo, X. Cao, P. Huang, and L. Yobas, “Microcapillary-assisted dielectrophoresis for single-particle positioning,” Lab on a Chip, vol. 12, pp. 4085-4092, 2012.