Swift vaccination is necessary as a response to disease outbreaks and pandemics; otherwise, the species under attack is at risk of a high fatality rate or even mass extinction. Statistics suggest that at least 16 billion injections are administered worldwide every year. Such a high rate of needle/syringe injection administration worldwide is alarming due to the risk of needle-stick injuries, disease spread due to cross-contamination and the reuse of needles, and the misuse of needles. In addition, there are production, handling, and disposal costs. Needle phobia is an additional issue faced by many recipients of injections with needles. In addition to a detailed literature review highlighting the need for needle-free injection systems, a compressed air-driven needle-free jet injection system with a hydro-pneumatic mechanism was designed and developed by employing an axiomatic design approach. The proposed injection system has higher flexibility, uninterrupted force generation, and provides the possibility of delivering repeated injections at different tissue depths from the dermis to the muscle (depending on the drug delivery requirements) by controlling the inlet compressed air pressure. The designed needle-free jet injector consists of two primary circuits: the pneumatic and the hydraulic circuit. The pneumatic circuit is responsible for driving, pressurizing, and repeatability. The hydraulic circuit precisely injects and contains the liquid jet, allowing us to control the volume of the liquid jet at elevated pressure by offering flexibility in the dose volume per injection. Finally, in this paper we report on the successful design and working model of an air-driven needle-free jet injector for 0.2–0.5 mL drug delivery by ex vivo experimental validation.

Owing to the quick response, compact structure, high precision, huge blocking force generation, and ease of operation, piezoelectric actuators are urgently being adopted in the field of advanced dispensing for jetting performance improvement and fulfillment of precision requirements in microelectronics packaging, adhesive bonding, and miniaturization industry. This research focuses on the fundamental design and development of a piezo-electrically driven compact fluid dispenser using the principle of a class-one lever for amplification of needle displacement, and enhancement of application areas of the developed jet dispenser. Using fundamental lever principle, geometry-based modelling is carried out to fabricate a working prototype of a normally closed hinge-lever type dispenser. Preliminary experiments are carried out to witness the workability of the fabricated dispenser to deliver 100 dots of working fluid per second that will provide a novel device for dispensing of various fluids, and the proposed amplification mechanism suits various other piezoelectric applications as well.

This study has been based on the examination of the characterization of ring-type lead zirconate titanate (PZT) ceramics for high-intensity focused ultrasonic dispersion system. The ring-type PZT ceramics were fabricated by the powder molding method. The mechanical properties, dielectric constant, and microstructure of the ceramics were investigated. Consequently, the density of the ceramics was increased with increasing forming pressure while the density of ceramics that were sintered at 1350 °C was decreased due to over-sintering. Furthermore, the mechanical properties were excellent at the higher forming pressure. The dielectric property of the ring-type PZT ceramics was not clearly influenced by the manufacturing and sintering conditions. The abnormal grain growth of the ceramics, however, could be prevented by a lower heating rate in addition to reducing the porosity.

Various research on a dispenser head applied with the technology of piezoelectric ceramics which has high response, force generation and resolution have been actively conducted. A piezoelectric dispenser head for functional high viscous liquid generates micro droplets utilizing a different mechanism with conventional valves. This mechanism makes it difficult to calculate the pressure build-up and flow quantity. Because of this difficulty, proper displacement of a tappet cannot be selected and the displacement of the piezoelectric ceramic is being used with excessive amplification. To address these issues, a piezo dispenser head has been modeled to numerically analyze this mechanism. The mechanism has been simulated to calculate the pressure build-up and flow quantity. In addition, the load on the tappet was calculated, and the appropriate displacement of the tappet was confirmed. In this study, we have succeeded in numerically analyzing the mechanism of the piezoelectric dispenser head and we confirmed that the displacement of the appropriate tappet is about 200 μm; at this time the load on the tappet is about 3.7 N and the droplet volume is about 19.89 nL.

The piezoelectric actuators as smart material actuator have been applied to fields which need high precision, fast response and high force. Jet dispensing heads which are generally driven by pneumatics require above mentioned characteristics. To make jet dispensing head being driven by piezoelectric actuators, it is essential to use piezoelectric actuators must be used with displacement amplification mechanism due to low displacement generated by the piezoelectric actuators only. Hence we fabricated displacement amplification mechanism by using three piezoelectric actuators. Experiments were carried out to investigate the amplified displacements, amplification ratio and the effects produced by increasing input frequency. In this study, we observed the characteristics of displacement amplifier experimentally and it is confirmed and concluded from results that if the input frequency increases, the effect of phase lag becomes conspicuous.