Penetrating microjets in soft substrates: towards controlled needle-free injections
The needle-free delivery of liquid jets into soft and heterogeneous substrates, e.g. human tissue, has been hindered by (1) the need to reach specific penetration depths with energy efficient means, (2) the break-up of jets that impedes control over the dose delivery, and (3) liquid splash-back after impacting the substrate that cause cross-contamination between injections. BuBble Gun is aimed at overcoming these challenges. My team and I have recently uncovered new operational regimes of cavitation with continuous-wave lasers. My next goal is to study the energy partition between the creation of bubbles, the formation of liquid jets, and the penetration of these jets into soft substrates. Fundamental insights on energy partitioning will then be applied to achieve major breakthroughs in jet injection, by (1) controlling cavitation within microfluidic confinement, (2) tuning the rheology of jets emerging from confined cavitation, and (3) deriving the relationships between fluid dynamics and material properties governing jet injection into soft substrates. I expect to advance the knowledge at the intersection of microfluidics, physics, and bioengineering, to enable unprecedented control over cavitation, jetting, and injection phenomena. We will develop a portable energy- efficient injection platform by using ultra-high-speed imaging, and quantifying injections with experimental resolutions below the microsecond and micrometer scales. The rheological properties of the jets will be tuned with biocompatible additives to ensure cohesion, before injecting them into in-vitro targets and ex-vivo skin. Numerical models will assist untangling the influence of microfluidic configuration and material properties on the injection outcomes. The ultimate result will be the predictable, reproducible, and efficient injection of liquids that will enable a wide-range of technologies, such as additive manufacturing, coating modifications, the delivery of drugs and vaccinations.