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Self-cleaning currency? Could be.

April 23, 2014 by Brendan Burge

We have all had the experience of receiving a poor quality, dirty banknote as change in a purchase. It might even have been issued by a bank teller, or worse, an ATM.

There are many reasons that dirty money is circulated. Most often, it is due to a lack of "fit" banknotes required to fill an order from the vault for a branch, ATM or commercial customer.

Another contributing factor is the growing central bank practice of allowing commercial banks to hold "custodial inventories." This practice results in a reduced flow of banknotes back to the central bank and therefore a reduced rate of destruction for mutilated banknotes.

Given the growing number of dirty banknotes in circulation, we can imagine the benefits of self-cleaning currency, if that were even a possibility. Apparently self-cleaning currency could very well become a reality. During our periodic research into currency related topics, we happened upon a recently published patent for self-cleaning currency.

The application summarizes the necessary technology and processes to make self-cleaning currency a reality. It will be up to the substrate manufacturers to determine how best to incorporate this technology with their existing paper, linen, cotton and polymer-based products.

The complete patent application is available from the U.S. Patent and Trademark Office website. Following is the Brief Summary of the Invention from the application:

Use of photo catalytic material for self-cleaning banknotes
Patent Application No.: 20140083473
Applicant: Nabil Lawandy, Saunderstown, R.I., U.S.
Assignee: Spectra Systems Corp., Providence, R.I., U.S.
[0011] [T]he present invention provides for substrate materials that include a self-cleaning and directed cleaning capability. More specifically, the present invention provides a substrate that includes a photo-catalytic material therein that, upon exposure to a source of illumination, reacts in a manner that causes the substrate and printing inks materials, to shed accumulated contaminants and dirt and a system for sorting, cleaning and analyzing banknotes formed using such a substrate material.
[0012] In general the present invention employs coatings, inks and additives which are photo-active and catalytic to reactions which are effective in breaking up organic contaminants or dirt. In some cases, photo-excitation of these materials also leads to interfaces which are super-hydrophilic allowing for more water to be split, producing more reactive OH radicals by the photo-catalytic materials and in turn breaking more organic contaminant bonds for eventual removal of the adhered materials (oxidized sebum and other contaminants). Such an effect desirably occurs through exposure to ambient light. The self-cleaning materials incorporated in banknotes can be additionally utilized beyond ambient light exposure using equipment with optical/UV excitation and flowing air, water flow, and mechanical brushes, thus removing soiling and increasing the usable life of banknotes.
[0013] The invention is usable with all substrates and particularly polymeric substrates such as biaxially-oriented polypropylene (BOPP). The invention further discloses a system which allows a certain class of fitness parameters to cause these banknotes to be redirected to a cleaning module, be reevaluated, and then either returned to circulation or destroyed. In addition, inks which are photo-catalytic can be used for extending the life of the banknotes in printed regions.
[0014] It is therefore an object of the present invention to provide a substrate material that provides high security against fraud while exhibiting increased durability and self-cleaning characteristics. It is a further object of the present invention to provide a substrate that through the use of coatings, inks and additives that are photo-active and catalytic to reactions which are effective in breaking up organic contaminants or dirt can be altered by light to allow for the self-cleaning of banknotes by ambient light exposure as well as the cleaning of processed banknotes using equipment with optical excitation, thus increasing their usable life. It is still a further object of the present invention to provide a system that using a certain class of fitness parameters causes identified banknotes to be redirected to a cleaning module prior to reevaluation and then a determination that they are either returned to circulation or destroyed.
[0015] These together with other objects of the invention, along with various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed hereto and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment of the invention.