Patents - Costs and accumulated amortization of patents (Details) - USD ($)	12 Months Ended
Jul. 31, 2014	Jul. 31, 2013	Apr. 30, 2015	Apr. 30, 2014
Accounting Policies [Abstract]
Patents	$ 5,725,908	$ 5,657,455
Less: Accumulated Amortization	3,679,547	3,338,039
Patents, Net	$ 2,046,361	$ 2,319,416	$ 1,835,267	$ 2,046,361
Weighted Average Life	7 years 9 months 18 days	8 years 7 months 6 days

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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