Note 11 - Capital Stock - Summary of Share Transactions (Details) - USD ($)		3 Months Ended	9 Months Ended
		Apr. 30, 2019	Apr. 30, 2019	Apr. 30, 2018
Balance (in shares)			161,175,764
Shares Issued, Price Per Share (in dollars per share)		$ 1.33	$ 1.33
Equity Financing, Issuance Value			$ 15,990,962
Credit Facility, Issuance Value			$ 1,400,000	$ 900,000
Exchange of Warrants (in shares)		750,000	750,000
Exchange of Warrants			$ 977,563
Consulting Services, Issuance Value			226,539	322,865
Warrants Exercised, Issuance Value			$ 4,822,357
Options Exercised, Issued (in shares)			217,750
Options Exercised, Issuance Value			$ 72,363	328,300
Shares Issued Under Stock Incentive Plan, Issuance Value			$ 785,117	$ 729,644
Stock Issued for Consulting Services [Member]
Consulting Services, Issued (in shares)			165,404
Consulting Services, Issuance Value			$ 226,539
Share-based Payment Arrangement, Option [Member]
Options Exercised, Issued (in shares)	[1]		118,985
Options Exercised, Issuance Value	[1]		$ 123,221
Shares Issued Under Stock Incentive Plan [Member]
Shares Issued Under Stock Incentive Plan, Issued (in shares)			558,875
Shares Issued Under Stock Incentive Plan, Issuance Value			$ 785,117
Warrants Exchanged for Common Shares [Member]
Exchange of Warrants (in shares)			750,000
Exchange of Warrants			$ 997,500
October 2018 Warrants [Member]
Warrants Exercised, Issued (in shares)			3,999,881
Warrants Exercised, Issuance Value			$ 4,822,357
Minimum [Member] | Stock Issued for Consulting Services [Member]
Shares Issued, Price Per Share (in dollars per share)		$ 1.23	$ 1.23
Minimum [Member] | Share-based Payment Arrangement, Option [Member]
Shares Issued, Price Per Share (in dollars per share)	[1]	0.45	0.45
Minimum [Member] | Shares Issued Under Stock Incentive Plan [Member]
Shares Issued, Price Per Share (in dollars per share)		1.25	1.25
Minimum [Member] | Warrants Exchanged for Common Shares [Member]
Shares Issued, Price Per Share (in dollars per share)		1.33	1.33
Minimum [Member] | October 2018 Warrants [Member]
Shares Issued, Price Per Share (in dollars per share)		1.20	1.20
Maximum [Member] | Stock Issued for Consulting Services [Member]
Shares Issued, Price Per Share (in dollars per share)		1.77	1.77
Maximum [Member] | Share-based Payment Arrangement, Option [Member]
Shares Issued, Price Per Share (in dollars per share)	[1]	1.32	1.32
Maximum [Member] | Shares Issued Under Stock Incentive Plan [Member]
Shares Issued, Price Per Share (in dollars per share)		1.72	1.72
Maximum [Member] | Warrants Exchanged for Common Shares [Member]
Shares Issued, Price Per Share (in dollars per share)		1.33	1.33
Maximum [Member] | October 2018 Warrants [Member]
Shares Issued, Price Per Share (in dollars per share)		1.35	$ 1.35
The 2018 October Offering [Member]
Equity Financing, Issued (in shares)			12,613,049
Equity Financing, Issuance Value			$ 20,180,878
The 2018 October Offering [Member] | Minimum [Member]
Shares Issued, Price Per Share (in dollars per share)		1.60	$ 1.60
The 2018 October Offering [Member] | Maximum [Member]
Shares Issued, Price Per Share (in dollars per share)		1.60	$ 1.60
Shares Issued for Credit Facility [Member]
Credit Facility, Issued (in shares)			1,180,328
Credit Facility, Issuance Value			$ 1,400,000
Shares Issued for Credit Facility [Member] | Minimum [Member]
Shares Issued, Price Per Share (in dollars per share)		1.19	$ 1.19
Shares Issued for Credit Facility [Member] | Maximum [Member]
Shares Issued, Price Per Share (in dollars per share)		$ 1.19	$ 1.19

[1] 151,500 stock options were exercised on a forfeiture basis, resulting in 52,735 net shares being issued.