Figure 1
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Figure 1 shows a powder dispensing drum and coated film web ready for die cutting into individual doses. Each 2cm diameter area shown
contains approximately 4.7 mg of API. The substrate is approximately 30 μm thick, giving a total coated thickness of approximately
100 μm, which allows the films to be easily rolled or folded for encapsulation or further processing. The technology also
enables packaging processes to be fully merged and automated into a complete, continuous commercial production line.
Figure 2
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Figure 2 shows a 3D computer-aided design model of a test rig unit delivering one dose per second. Further optimization, however,
could improve this rate; for example, a multiple lane production machine with 16 lines in parallel would deliver approximately
60000 doses per hour.
Web films, adhesives and dissolution
Aside from the powderdispensing module, the other two main system components are the web or film carrier and the printable
adhesive.
Edible or inert films have been widely used within the food processing industry for years because they are safe to ingest,
while also being robust and flexible enough for standard web handling. Growing interest in thin-film drug delivery and controlledrelease
encapsulation technologies has also generated unusual new films and materials that can be exploited within the sticky web
process.
As part of the development programme, 42T investigated existing edible pressure-sensitive adhesives (PSA) and developed a
range of new substances, which offer instant tack in the dry state and gently adhere to the steel powderdispensing drum, but
also peel without leaving any residue. In addition, these new adhesives offer good powder adhesion and dissolve readily in
water.
Figure 3
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Figure 3 shows a 20× magnification of a typical powdered area generated with one of these new adhesives; the edges are clean, and
there is even powder distribution and adherence of large and small particles within the sample.
Future developments
The bulk of development activity so far has been angled towards the pharmaceutical sector using edible flat carriers, but
the adhesive could just as easily be printed onto other surfaces, including bubbles or tablets, which are then subsequently
dosed with powders. Two or more substances could even be combined in the same delivery package.
The technology is also viable for virtually any industry requiring accurate, high-volume dosing of powders to improve existing
manufacturing processes or generate innovative new products or processes.
"Sticky Web offers considerable promise for high-speed production environments where online inspection systems could be used
to validate every powdered area and to improve process feedback, increase efficiency and reduce costs," said Smith.
One of the most interesting features of Sticky Web is the potential for improved release of active powders that have a tendency
to agglomerate during dissolution when delivered via powder-coated films compared with capsules. Some initial development
work has suggested a marked improvement, but further validation studies would be required for specific adhesive and powder
combinations.
Howard Biddle is Managing Director of 42 Technology (UK). howard.biddle@42technology.com
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