Page 82 - ASME_NEMB_2016_Program

Technical Program TRACK 6

Fabrication And Characterization Of A Sensor Integrated on Lab- droplets from a ferrofluid reservoir. Once a jet of ferrofluid is subjected to
On-A-Chip To Detect H2S In Biological Samples. a constrained flux through a membrane and an inhomogeneous magnetic
field, the jet experiences a curvature-driven instability and transforms to a
Poster Presentation. NEMB2016-6036 droplet. In this approach, a ferrofluid reservoir is covered with a membrane.
An imposed inhomogeneous localized magnetic field to the reservoir gener-
ates a continuous jet of ferrofluid. Once the jet flows through the membrane,
Ashok Baniya, Latech, Ruston, LA, United States, Leland Weiss, the jet experiences a constrained flux. The combination of constrained flux
Louisiana Tech University, Ruston, LA, United States, Prabhu Aru- and inhomogeneous magnetic force results in the thinning of the ferrofluid
mugam, latech, Ruston, LA, United States jet. As the ferrofluid jet becomes thin enough, the developed Laplace pres-
sure in the ferrofluid jet leads to capillary instability and back-flow of the
Blood gas measurement are used to evaluate a person’s lung function and ferrofluid to the reservoir. This back-flow leads to breaking of the fluid jet
acid /base balance. The proposed sensor integrated lab on the chip device into a droplet. Volumes of the dispensed droplets are tuned in the range of
was manufactured to severe the diagnostic purposes of such applications. 0.1-1000 nanoliter by the induced magnetic field and hydraulic resistance of
Currently, the novel chip was designed to detect the level of hydrogen the membrane. Furthermore, the frequency of droplet dispensing is adjusted
sulfide present in the blood. Hydrogen sulfide (H2S) has emerged as an im- with the magnetic field and type of the membrane. A mathematical model
portant signaling molecule that plays significant roles in health and disease. is developed to elucidate the dynamics of the ferrofluid jet. This mathe-
Work from many labs has revealed that H2S bioavailablilty and exogenous matical model includes two parts. In the first part, the dynamics of ferrofluid
hydrogen sulfide therapy regulate numerous disease states including inflam- jet-front between the reservoir and the magnet is modeled. In the second
mation, cancer, cardiovascular, neurological and gastrointestinal diseases. part, the dynamics of thinning of the ferrofluid jet is studied. In this mathe-
As the significance of H2S grows, the ability to foster clinical detection and matical model, we solve Darcy equation along with mass and momentum
promote treatment becomes increasingly critical. Current technology relies conservations to predict the dispended volume of the ferrofluid. Once the
on elaborate methodologies that impede real world use in a clinical setting. ferrofluid properties, characteristics of the membrane, and the spatial form
Present day small scale systems are incapable of micro-molar (µM) H2S of magnetic field are given, the model predicts the dispensed volume of the
detection. This is a critical limitation because disease detection requires this ferrofluid. There is an excellent agreement between the model’s predictions
degree of precision. This constraint further hampers the ability to expand and the measurements. The developed approach promises a simple route
detection and treatment to medical fields in third world applications or other to dispense miniature volume of ferrofluid in biotechnologies, optics, energy
environments where cost is a significant issue. systems, and even aerospace technologies with no need of complex drop-
let generation devices.
This proposed work investigates and demonstrates new H2S detection
techniques well suited to disease detection and biomedical application
through a Lab on a Chip (LOC) approach. A unique LOC device has a vari- Turning the Sensitivity of Point-of-Care Test by Gold Nanoparti-
ous parts which serves as specific purpose. The micro-fabricated layer was cle Aggregation: Effects of Nanoparticle Concentration and Size
coated with the sulfide liberation buffer. The liberated gas was then passed
via a highly selective polymer membrane and then collected at the final
chamber for its quantification. Poster Presentation. NEMB2016-6103

A sensor integrated LOC device to detect all forms of H2S in biological sam- Peiyuan Kang, The University of Texas at Dallas, Richardson, TX,
ples has been fabricated and characterized. The carbon nanotube modified United States, Naga Aravind Revuru, Zhenpeng Qin, University of
boron doped-UNCD electrode was designed to detect the H2S in micromo- Texas at Dallas, Richardson, TX, United States
lar to submicromolar range in biological sample. Both direct and indirect de-
tection have been investigated and compared. Detection of sulfide via the Point-of-Care (POC) diagnosis of infectious diseases continues to be in ur-
catalytic electrochemical oxidation of ferrocyanide was much promising and gent need and can lead to early diagnosis and treatment. POC diagnosis re-
low power consumption. This research highlights the modification of sensor quires a fast assay time, minimal infrastructure, and sufficient sensitivity and
integrated lab on the chip device to detect sulfide in biological range in a specificity. Among the various infectious disease biomarkers, the amplifica-
water based sample. The optimized sensor have a linear detection which tion and detection of pathogen’s nucleic acid sequence has been shown to
makes the sensor possible for calibration. The limit of detection was 0.1 µM. be highly sensitive and specific. To detect the target nucleic acid sequence,
The detection of the gas was less labor intensive, fast and low cost com- a gold nanoparticle (GNP)-based aggregation assay has shown great prom-
pared to the any other techniques due to its possibility of the miniaturization ise to meet the POC requirements. For this assay, GNPs were conjugated
and batch fabrication. with two different DNA sequences that are complementary to target nucleic
acid sequence to create “probes”. The probes hybridize with the target
nucleic acid to form GNP aggregates which induce a color change due to
Nano Droplets of Ferrofluids the altered plasmon resonance. Previous work has reported the optimized
reaction conditions and detection methods. The goal of this work is to inves-
Poster Presentation. NEMB2016-6100 tigate the effects of GNP probe concentration and size on the assay perfor-
mance. Malaria parasite genus Plasmodium was chosen as a clinically rele-
Peyman Irajizad, Nazanin Farokhnia, Hadi Ghasemi, University of vant target. A poly A-tail was included in the probes to increase flexibility of
the sequence. The HPLC-purified probes were synthesized and purchased
Houston, Houston, TX, United States from Bio Basic Canada Inc. GNPs were prepared by reducing gold chloride
by sodium citrate. To conjugate DNA probes to GNPs, we followed a pH-as-
Ferrofluids are fluids with properties tailored on the nanometer scale. They sisted and surfactant-free method reported earlier. The complementary tar-
consist of single domain magnetic nano-particles dispersed in a liquid car- get was then hybridized with GNP probes for 30 min at room temperature in
rier. As their properties are remotely tunable by a magnetic field, ferrofluids the presence of a hybridization buffer which consisted of 20 % Formamide,
are exploited in a broad range of disciplines including magnetic drug target- 16% dextran sulfate and 0.6 M NaCl. The optical spectrum was measured
ing, cancer treatment by magnetic hyperthermia, contrast agent in magnetic using a Beckman Coulter UV-Vis spectrophotometer (model DU800). The
resonance imaging (MRI), magnetic-capillary self-assembly, optics, sensors, probe nucleic acid conjugation on GNP leads to plasmon resonance peak
and mechanical sealing and acoustic. In these implementations, dispensing shift from 518 to 524 nm and hydrodynamic diameter increase by 9 nm for
a small volume of fluid is in demand. Current systems for dispensing ferroflu- 15nm GNP. Within the concentration range studied here, increasing the GNP
id droplets at small volumes are mostly based on microfluidics flow-focusing probe concentration shifts the dynamic range of the assay to higher target
82 approaches, induced acoustic actuation, or conventional injection systems, sequence concentrations and thus compromises the limit of detection.
requiring complicated dispensing systems. Here, we present a facile ap- For instance, a low probe concentration (0.4nM) can detect down to 0.1nM
proach to continuously/intermittently dispense nano/pico liter ferrofluid while a higher probe concentration (10nM) can only detect down to ~10nM.