Hypothesis: Needle-free injections using microfluidic jets could be optimized by reducing splashing and controlling injection depth. However, this is impeded by an incomplete understanding on how jet characteristics influence impact outcome. We hypothesise that exploring the relation between microfluidic jet characteristics and substrate shear modulus on impact behavior will assist in predicting and giving insights on the impact outcome on skin and injection endpoints.
Experiments: To do so, a setup using microfluidic chips, at varying laser powers and stand-off distances, was used to create thermocavitation generated microfluidic jets with ranging characteristics (velocity: 7-77 m/s, diameter: 35-120 μm, Weber-number: 40-4000), which were impacted on substrates with different shear modulus.
Findings: Seven impact regimes were found, depending on jet Weber-number and substrate shear modulus, and we identified three thresholds: i) spreading/splashing threshold, ii) dimple formation threshold, and iii) plastic/elastic deformation threshold. The regimes show similarity to skin impact, although the opacity of skin complicated determining the threshold values. Additionally, we found that jet velocity has a higher predictive value for injection depth compared to the Weber-number, and consequently, the jet-diameter. Our findings provide fundamental knowledge on the interaction between microfluidic jets and substrates, and are relevant for optimizing needle-free injections.
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http://dx.doi.org/10.1016/j.jcis.2023.01.024 | DOI Listing |
Soft Matter
October 2024
Department of Mechanical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
Small
October 2024
State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.
Nanoparticle surfactants have been widely used to construct structured liquids in oil-water systems. Less attention, though, has been given in non-aqueous systems, for example, oil-oil systems, mainly due to the lack of suitable surfactants. Here, by using newly developed molecular brush surfactants (MBSs) that form at the DMSO-silicone oil interface, the construction of all-oil microfluidic devices is reported with advanced functions.
View Article and Find Full Text PDFBiosens Bioelectron
October 2024
College of Engineering and Applied Sciences, Nanjing University, Nanjing, 210093, PR China; Key Laboratory of Intelligent Optical Sensing and Integration of the Ministry of Education, Nanjing University, Nanjing, 210009, PR China; Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, PR China. Electronic address:
Surface enhanced Raman spectroscopy (SERS) utilizes the fingerprint features of molecular vibrations to identify and detect substances. However, in traditional single focus excitation scenarios, its signal collection efficiency of the objective is restricted. Furthermore, the uneven distribution of samples on the SERS substrate would result in poor signal stability, while the excitation power is limited to avoid sample damage.
View Article and Find Full Text PDFJ Fluid Mech
May 2024
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Cd. Universitaria, 04510 Mexico City, Mexico.
Studying liquid jet impacts on a liquid pool is crucial for various engineering and environmental applications. During jet impact, the free surface of the pool deforms and a cavity is generated. Simultaneously, the free surface of the cavity extends radially outward and forms a rim.
View Article and Find Full Text PDFAdv Mater
February 2024
Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui, 230026, China.
Microfluidics, with its remarkable capacity to manipulate fluids and droplets at the microscale, has emerged as a powerful platform in numerous fields. In contrast to conventional closed microchannel microfluidic systems, free-boundary microfluidic manufacturing (FBMM) processes continuous precursor fluids into jets or droplets in a relatively spacious environment. FBMM is highly regarded for its superior flexibility, stability, economy, usability, and versatility in the manufacturing of advanced materials and architectures.
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