Microfluidic diagnostics for the developing world.

Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA.
Lab on a Chip (Impact Factor: 5.7). 03/2012; 12(8):1412-6. DOI: 10.1039/c2lc90022j
Source: PubMed

ABSTRACT For more than a decade, it has been expected that microfluidic technology would revolutionize the healthcare industry with simple, inexpensive, effective, and ubiquitous miniature diagnostic devices. To date, however, microfluidics has not yet been able to live up to these expectations. This fact has led to the recent development of new philosophies and methodologies for microfluidic diagnostics. In this Focus article, we will discuss some of the latest breakthroughs that could significantly impact medical diagnostics in the developing world.

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work, we develop an in situ method to grow highly controllable, sensitive, three-dimensional (3D) surface-enhanced Raman scattering (SERS) substrates via an optothermal effect within microfluidic devices. Implementing this approach, we fabricate SERS substrates composed of Ag@ZnO structures at prescribed locations inside microfluidic channels, sites within which current fabrication of SERS structures has been arduous. Conveniently, properties of the 3D Ag@ZnO nanostructures such as length, packing density, and coverage can also be adjusted by tuning laser irradiation parameters. After exploring the fabrication of the 3D nanostructures, we demonstrate a SERS enhancement factor of up to ∼2 × 10(6) and investigate the optical properties of the 3D Ag@ZnO structures through finite-difference time-domain simulations. To illustrate the potential value of our technique, low concentrations of biomolecules in the liquid state are detected. Moreover, an integrated cell-trapping function of the 3D Ag@ZnO structures records the surface chemical fingerprint of a living cell. Overall, our optothermal-effect-based fabrication technique offers an effective combination of microfluidics with SERS, resolving problems associated with the fabrication of SERS substrates in microfluidic channels. With its advantages in functionality, simplicity, and sensitivity, the microfluidic-SERS platform presented should be valuable in many biological, biochemical, and biomedical applications.
    ACS Nano 11/2014; · 12.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Preconcentration of pathogens from patient samples represents a great challenge in point-of-care (POC) diagnostics. Here, a low-cost, rapid, and portable agarose-based microfluidic device was developed to concentrate biological fluid from micro- to pico-liter volume. The microfluidic concentrator consisted of a glass slide simply covered by an agarose layer with a binary tree-shaped microchannel, in which pathogens could be concentrated at the end of the microchannel due to the capillary effect and the strong water permeability of the agarose gel. The fluorescent Escherichia coli strain OP50 was used to demonstrate the capacity of the agarose-based device. Results showed that 90% recovery efficiency could be achieved with a million-fold volume reduction from 400 µL to 400 pL. For concentration of 1×10(3) cells mL(-1) bacteria, approximately ten million-fold enrichment in cell density was realized with volume reduction from 100 µL to 1.6 pL. Urine and blood plasma samples were further tested to validate the developed method. In conjugation with fluorescence immunoassay, we successfully applied the method to the concentration and detection of infectious Staphylococcus aureus in clinics. The agarose-based microfluidic concentrator provided an efficient approach for POC detection of pathogens.
    Analytical Chemistry 09/2014; · 5.83 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study focuses on the fabrication of a novel, flexible and disposable textile based biosensing platform by the use of an absorbent microfibrous nonwoven substrate as the base material. This platform was fabricated via photolithography technique. Physical barriers were designed using a hydrophobic photo-resist polymer which defined the liquid penetration pathways on the fabric surface. A good hydrophilic/hydrophobic contrast of the fabricated patterns on the fabric and a well-controlled liquid capillary penetration was achieved in the patterns. The potential of the system was tested by constructing an enzyme biosensor based on colorimetric detection of hydrogen peroxide. To obtain a more enhanced and reproducible signal, the reservoirs were modified with gelatin and a linear working range of 0.1–0.6 μM H2O2 was obtained. The system could work on temperatures as high as 50 °C without any loss in the signal and in a pH range of 3.0–7.0. This bio-sensing platform may later be combined by H2O2 producing oxidases such as glucose oxidase, lactate oxidase, etc. and used for the rapid detection of various kinds of important analytes.
    Sensors and Actuators B Chemical 03/2015; 208:475-484. · 3.84 Impact Factor