10 June 2019:
A team of CNBP researchers have published a new paper discussing the design and application of a micro fabricated needle-like probe to measure hydrogen peroxide. This new microfluidic tool has applications for monitoring dynamic chemical reactions in analytical chemistry and biological systems.
Journal: RSC Advances
Publication Title: Microfabricated needle for hydrogen peroxide detection
Authors: Shilun Feng, Sandhya Clement, Yonggang Zhu, Ewa M. Goldys and David W. Inglis
Abstract: A microfabricated needle-like probe has been designed and applied for hydrogen peroxide (H2O2) sampling and detection using a commercial, single-step fluorescent H2O2 assay. In this work, droplets of the assay reagent are generated and sent to the needle tip using a mineral-oil carrier fluid. At the needle tip, the sample is drawn into the device through 100 mm long hydrophilic capillaries by negative pressure. The sampled fluid is immediately merged with the assay droplet and carried away to mix and react, producing a sequence of droplets representing the H2O2 concentration as a function of time. We have characterized the assay fluorescence for small variations in the sample volume. With the calibration, we can calculate the concentration of H2O2 in the sampled liquid from the size and intensity of each merged droplet. This is a microfluidic data-logger system for on-site continuous sampling, controlled reaction, signal storage and on-line quantitative detection. It is a useful tool for monitoring dynamic chemical reactions in analytical chemistry and biological applications.
Key words: Microfluidics, probe, H2O2, analytics chemistry
16 November 2017:
CNBP and Macquarie University PhD candidate Shilun Feng is first author on a new paper exploring a ‘membrane-on-a-chip’ device. The technology has the potential to form an integral part of a new type of microneedle that would be able to transport tiny and precise amounts of fluid/medication within the body.
Publication title: Microfluidic Droplet Extraction by Hydrophilic Membrane.
Authors: Shilun Feng, Micheal N. Nguyen, and David W. Inglis.
Abstract: Droplet-based microfluidics are capable of transporting very small amounts of fluid over long distances. This characteristic may be applied to conventional fluid delivery using needles if droplets can be reliably expelled from a microfluidic channel. In this paper, we demonstrate a system for the extraction of water droplets from an oil-phase in a polymer microfluidic device. A hydrophilic membrane with a strong preference for water over oil is integrated into a droplet microfluidic system and observed to allow the passage of the transported aqueous phase droplets while blocking the continuous phase. The oil breakthrough pressure of the membrane was observed to be 250 ± 20 kPa, a much greater pressure than anywhere within the microfluidic channel, thereby eliminating the possibility that oil will leak from the microchannel, a critical parameter if droplet transport is to be used in needle-based drug delivery.
A new paper from CNBP researchers (lead author Shilun Feng pictured) reports on the development of a microfluidic needle-like device that can extract and deliver nanoliter samples.
The paper, published in ‘Applied Physics Letters’ is accessible online.
Journal: Applied Physics Letters.
Publication title: A microfluidic needle for sampling and delivery of chemical signals by segmented flows.
Authors: Shilun Feng, Guozhen Liu, Lianmei Jiang, Yonggang Zhu, Ewa M. Goldys, and David W. Inglis.
Abstract: We have developed a microfluidic needle-like device that can extract and deliver nanoliter samples. The device consists of a T-junction to form segmented flows, parallel channels to and from the needle tip, and seven hydrophilic capillaries at the tip that form a phase-extraction region. The main microchannel is hydrophobic and carries segmented flows of water-in-oil. The hydrophilic capillaries transport the aqueous phase with a nearly zero pressure gradient but require a pressure gradient of 19 kPa for mineral oil to invade and flow through. Using this device, we demonstrate the delivery of nanoliter droplets and demonstrate sampling through the formation of droplets at the tip of our device. During sampling, we recorded the fluorescence intensities of the droplets formed at the tip while varying the concentration of dye outside the tip. We measured a chemical signal response time of approximately 3 s. The linear relationship between the recorded fluorescence intensity of samples and the external dye concentration (10–40 μg/ml) indicates that this device is capable of performing quantitative, real-time measurements of rapidly varying chemical signals.