title: Development of high-throughput glass inkjet devices for pharmaceutical applications.
abstract: The application of the inkjet method to pharmaceutical products is promising. To make this realistic, not only does the throughput of this method need to be increased, but also the components should be inert to pharmaceutical preparations. We present designs of glass-based inkjet devices that are capable of producing droplets at high rates. To achieve this, inkjet devices from glass capillary tubes were manufactured with orifice diameters of 5, 10 and 20 μm and were actuated with diaphragm piezoelectric disks. Also, a pressure capsule was formed by creating a manifold at a distance from the orifice tip. Placing the piezoelectric disk at 0.5 mm distance from the tip allowed the formation of a jet at 3.2 MHz in certain designs, but for a short period of time because of overheating. The length of the pressure capsule, its inlet diameter, and the nozzle tip geometry were crucial to lower the required power. Actuating an inkjet device with 10 μm orifice diameter comfortably at 900 kHz and drying the droplets from 1% salbutamol sulphate solution allowed the formation of particles with diameters of 1.76 ± 0.15 μm and the geometric standard deviation of 1.08. In conclusion, optimising internal design of glass inkjet devices allowed the production of high-throughput droplet ejectors.
authors.affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK. Electronic address: t.ehtezazi@ljmu.ac.uk.
authors.forename: Touraj
authors.initials: T
authors.lastname: Ehtezazi
authors.affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Dempster
authors.affiliation: Inkjet Research Centre, IfM, Department of Engineering, University of Cambridge, Cambridge CB3 0FS, UK.
authors.forename: Graham D
authors.initials: GD
authors.lastname: Martin
authors.affiliation: Inkjet Research Centre, IfM, Department of Engineering, University of Cambridge, Cambridge CB3 0FS, UK.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Hoath
authors.affiliation: Inkjet Research Centre, IfM, Department of Engineering, University of Cambridge, Cambridge CB3 0FS, UK.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Hutchings
mesh_terms: D000420:Albuterol / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D003460:Crystallization; D018360:Crystallography, X-Ray; D004867:Equipment Design; D005898:Glass; D057166:High-Throughput Screening Assays / Q000295:instrumentation*; D010316:Particle Size; D033362:Powder Diffraction; D011312:Pressure; D011327:Printing / Q000295:instrumentation*; D013678:Technology, Pharmaceutical / Q000295:instrumentation*; D013818:Thermogravimetry
chemical_list: D000420:Albuterol
keywords: crystallography; high throughput; inkjet devices; pharmaceutical inhalers; powder technology; pulmonary; solid state; spray drying; uniform particles