Bioprinting technology has been rapidly increasing in popularity in the field of tissue engineering. Potential applications include tissue or organ regeneration, creation of biometric multi-layered skin tissue, and burn wound treatment [1]. Recent work has shown that living cells can be successfully applied using inkjet heads without damaging the cells [2]. Electrostatically driven inkjet systems have the benefit of not generating significant heat and therefore do not damage the cell structure. Inkjets have the additional benefit of depositing small droplets with micrometer resolution and therefore can be used to build up tissue like structures. Previous attempts at tracking and drawing on a hand include either direct contact with the hand [3] or tracking the hand only in two degrees of freedom [4]. In this work we present an approach to track a hand with three degrees of freedom and accurately apply a substance contact free to the hand in a desired pattern using a bioprinting compatible inkjet. The third degree of freedom, in this case depth from the hand surface, provides improved control over the distance between the inkjet head and object, thus increasing deposition accuracy.

In this study, the hydrodynamic and structural aspects of the NPC are explored with respect to droplet generation and selective sorting through a design concept and several simulations were carried out to investigate the feasibility.

Monodisperse micron-sized aerosol is ideal for pulmonary drug delivery. This paper reports delivery of monodisperse aerosol of medicinal droplets generated by MHz ultrasonic nozzles using an anatomically realistic upper airway model. The MHz ultrasonic nozzle is fabricated using MEMS technology, and comprised of a piezoelectric drive section and a silicon resonator of multiple Fourier horns (see Fig. 1) [1]. The dissolved medication is pumped into a central channel (200×200 μm 2 ) inside the nozzle and exits at the nozzle tip that vibrates longitudinally at the nozzle resonant frequency. The novel design of multiple horns facilitates generation of a column of monodisperse droplets at electric drive power as low as 15mW [1]. Monodisperse ethanol droplets 2.4 μm and water droplets 4.5 μm in diameter have been produced, respectively, using 1.5 MHz and 1.0 MHz nozzles. We used an aqueous solution of 25mg/ml (2.5wt%) β 2 -agonist (isoproterenol) for generation of monodisperse droplets using the 1.0 MHz ultrasonic nozzles. A yield of >54% (to the lower airways on total amount of inhaled isoproterenol basis), significantly higher than the reported highest lower airways deposition (32%) using metered-dose-inhalers (MDIs) [2], has been accomplished.

This paper reports production of 4.5 μm-diameter monodisperse water droplets using silicon-based one MHz ultrasonic nozzles of a novel design. The novel design of multiple Fourier horns in resonance facilitates pure capillary wave mechanism atomization. The measured drop diameters are in very good agreement with those predicted by the capillary wave atomization mechanism. Due to the resonance effect, the power and voltage requirements for atomization were as low as 15 mW and 6.5 V at atomization rate as high as 300 μl/min. The droplet diameter was reduced to 4.1 μm when the surface tension of the liquid was reduced from 70 dyne/cm (water) to 50 dyne/cm (0.25% Triton X-100 surfactant solution). Such small diameter drops with GSD (geometrical standard deviation) as small as 1.1 was achieved in ultrasonic atomization for the first time. Note that the fraction of all particles smaller than 5.8 μm in diameter represents the inhaleable fine particle fraction and GSD of 1.3 or smaller is commonly accepted as the standard for monodispersity. Therefore, the MEMS-based MHz ultrasonic nozzle should have very significant impacts on targeted delivery of reproducible doses of medicine to the respiratory system.

Microfluidic droplet systems have shown great promise and numerous advantages in the recent development of high throughput chemical and biochemical assays. With precise metering and manipulation of reagents at small scale, various applications such as protein crystallization [1], nanoparticle synthesis [2], physiological fluids diagnostics [3] and etc. have employed such systems and achieved success.

This paper reports the design and simulation of Si-based ultrasonic nozzles (or atomizers) that consist of multiple Fourier horns at ultrasonic frequency ranging from 0.57 to 2.75 MHz. Such high frequency ultrasonic nozzles should produce monodispersed droplets (or drops) 2 to 6 μm in diameter, which are ideal to efficiently target medications to different locations within the respiratory system depending on the site of disease. 3-D simulations on vibration mode shape and impedance of the nozzles using a commercial finite element method (FEM) program, ANSYS, yield resonant frequencies of pure longitudinal vibration in good agreement with the measured values. The mode shape simulation also shows that at the resonant frequency the longitudinal vibration amplitude gain at the nozzle tip for 3-horn nozzle is 8, four times that for a single-horn nozzle.