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1. Transient modeling of impact driven needle-free injectors

   Rane, Y.S.; Marston, J.O. (June 2021, Computers in biology and medicine)

   Needle-free jet injectors (NFJIs) are one of the alternatives to hypodermic needles for transdermal drug delivery. These devices use a high-velocity jet stream to puncture the skin and deposit drugs in subcutaneous tissue. NFJIs typically exhibit two phases of jet injection – namely – an initial peak-pressure phase (< 5 ms), followed by a constant jet speed injection phase (≳ 5 ms). In NFJIs, jet velocity and jet diameter are tailored to achieve the required penetration depth for a particular target tissue (e.g., intradermal, intramuscular, etc.). Jet diameter and jet velocity, together with the injectant volume, guide the design of the NFJI cartridge and thus the required driving pressure. For device manufacturers, it is important to rapidly and accurately estimate the cartridge pressure and jet velocities to ensure devices can achieve the correct operational conditions and reach the target tissue. And thus, we seek to understand how cartridge design and fluid properties affect the jet velocity and pressure profiles in this process. Starting with experimental plunger displacement data, transient numerical simulations were performed to study the jet velocity profile and stagnation pressure profile. We observe that fluid viscosity and cartridge-plunger friction are the two most important considerations in tailoring the cartridge geometry to achieve a given jet velocity. Using empirical correlations for the pressure loss for a given cartridge geometry, we extend the applicability of an existing mathematical approach to accurately predict the jet hydrodynamics. By studying a range of cartridge geometries such as asymmetric sigmoid contractions, we see that the power of actuation sources and nozzle geometry can be tailored to deliver drugs with different fluid viscosities to the intradermal region. 

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2. Volumetric Flow Field inside a Gas Stirred Cylindrical Water Tank

   https://doi.org/10.3390/fluids9010011  

   Jojo-Cunningham, Yasmeen; Guo, Xipeng; Zhou, Chenn; Liu, Yun (January 2024, Fluids)

   Ladle metallurgy serves as a crucial component of the steelmaking industry, where it plays a pivotal role in manipulating the molten steel to exercise precise control over its composition and properties. Turbulence in ladle metallurgy influences various important aspects of the steelmaking process, including mixing and distribution of additives, alongside the transport and removal of inclusions within the ladle. Consequently, gaining a clear understanding of the stirred flow field holds the potential of optimizing ladle design, improving control strategies, and enhancing the overall efficiency and steel quality. In this project, an advanced Particle-Tracking-Velocimetry system known as “Shake-the-Box” is implemented on a cylindrical water ladle model while compressed air injections through two circular plugs positioned at the bottom of the model are employed to actively stir the flow. To mitigate the particle images distortion caused by the cylindrical plexi-glass walls, the method of refractive matching is utilized with an outer polygon tank filled with a sodium iodide solution. The volumetric flow measurement is achieved on a 6 × 6 × 2 cm domain between the two plugs inside the cylindrical container while the flow rate of gas injection is set from 0.1 to 0.4 L per minute. The volumetric flow field result suggests double gas injection at low flow rate (0.1 L per minute) produce the least disturbed flow while highly disturbed and turbulent flow can be created at higher flow rate of gas injection. 

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3. Effect of air pockets in drug delivery via jet injections

   https://doi.org/10.1016/j.ijpharm.2021.120547  

   Rohilla, P.; Khusnatdinov, E.; Marston, J.O. (April 2021, International journal of pharmaceutics)

   Needle-free jet injections are actuated by a pressure impulse that can be delivered by different mechanisms to generate high-speed jets (Vj ∼ 102 m/s). During filling and transportation of disposable cartridges and ampoules, bubbles can form, which can be problematic especially for viscous fluids. Here, we report on the effect of location and size of entrapped air pockets in cartridges used in spring-powered jet injections. As air bubbles pass through the orifice, they undergo depressurization, which results in intermittent atomization and spray formation, temporarily increasing the jet dispersion. Atomization and dispersion of the jet can lead to product loss during an injection. We find that the effect of bubble location on the jet exit speed, delivery efficiency, and the projected area of the blebs formed after the injection was statistically significant (p < 0.05). The findings of this study have implications for the development of pre-filled cartridges for jet injection applications. 

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4. Pressure monitoring of disposable reservoirs in North-Central Oklahoma: implications for geoseismicity and geostorage

   Allen, B; Murray, K; Ogwari, P; Suriamin, F; Walter, JI; Hayman, NW (November 2024, Journal of geological research)

   Disposal of industrial wastewater and activities such as CO2 depend on pressure conditions within deep geologic reservoirs. Injection and storage are also associated with induced seismicity, suggested to result from reservoir compartmentalization and leakage into faults. To understand subsurface pressure conditions within a major regional disposal reservoir, the carbonate Arbuckle Group of Oklahoma, we monitored the water levels in 15 inactive injection wells. The wells were monitored at 30-second intervals, with eight wells monitored since September 2016, and an additional seven from July 2017. All of the wells were monitored until early March 2020. Since 2016, well levels decreased in 3 of the 15 wells (a.k.a. hydraulic head), proportional to near-borehole fluid pressure even considering decreasing regional injection volumes during this period. The well pressures respond to three types of perturbations: (i) gravitational fkuctuations (a.k.a. solid-earth tides) (ii) distal and proximal earthquakes, and (iii) injections into nearby wells. Parameterization of tidal responses illustrates that the near wellbore environments have negative fluid flux (i.e. are leaking). Earthquakes cause differing pressure responses from well to well, with some highly sensitive to proximal events, some to distal events, and some apparently insensitive. Injections have variable impacts in some cases masking tidal and earthquake pressure signals. Collectively, there appears to be a threshold injection rate above which well pressure becomes less sensitive to the volume of injections within 15 km. Multi-scale geological structure and temporal permeability changes are likely controlling the pressure field, indicating leakage of fluids across the system. 

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5. Design and Experimental Evaluation of Mosquito-Inspired Needle Structure in Soft Materials

   https://doi.org/10.1115/IMECE2020-24320  

   Gidde, Sai Teja; Hutapea, Parsaoran (November 2020, Proceedings of the ASME 2020 International Mechanical Engineering Congress and Exposition)

   null (Ed.)

   Insects steer their stingers effortlessly to a specific target and release their venom in a certain path through the skin with minimal pain. These unique traits inspire the idea to develop bioinspired needles to reduce the insertion forces and to decrease the needle path deviation (deflection) for improved targeting accuracy. Our approach in this work focus on the design of mosquito-inspired needle and evaluation of the needle performance using vibration during tissue insertion. The mosquito-inspired needle design specifically consists of maxilla-shaped and labrum-tip design. The insertion force was measured using a force sensor, which was fixed at the needle end to measure the uniaxial force of needles. The applied vibration on the needle was measured along linear axis using piezoelectric actuator with a frequency of 150 Hz and an amplitude of 5μm. The needle was inserted at a constant speed by attaching the needle to a motorized linear stage. It was observed that the insertion forces of the proposed needle design with vibration showed a reduction by 27% compared to that of a conventional needle. This reduction in insertion force means that there is decrease in tissue gel phantom damage and it was also observed that needle bending has reduced due to reduction in bending stiffness of the tissue phantom. Furthermore, the needle insertion tests in real tissues (bovine kidney) considering the proposed needle geometry and vibration will be studied in future work to understand the bioinspired needle-tissue interactions. 

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