Note 11 - Capital Stock - Summary of Share Transactions (Details) - USD ($)	3 Months Ended				6 Months Ended
	Jan. 31, 2019		Oct. 31, 2018		Jan. 31, 2019		Jan. 31, 2018
Balance (in shares)	176,123,390		161,175,764		161,175,764
Stock Issued During Period, Value, New Issues					$ 15,990,962
Consulting Services, Issuance Value					178,454
Warrants Exercised, Issuance Value					$ 2,496,617
Options Exercised, Issued (in shares)	25,000		183,500		117,386
Options Exercised, Issuance Value					$ 72,363
Shares Issued Under Stock Incentive Plan, Issued (in shares)					364,702		451,101
Shares Issued Under Stock Incentive Plan, Issuance Value					$ 529,492		$ 616,468
Credit Facility, Issuance Value					$ 1,400,000
Balance (in shares)	177,642,699		176,123,390		177,642,699
October 2018 Warrants [Member]
Warrants Exercised, Issued (in shares)			2,061,764
Warrants Exercised, Issuance Value			$ 2,496,617
Stock Issued for Consulting Services [Member]
Consulting Services, Issued (in shares)	98,861		30,845
Consulting Services, Issuance Value	$ 127,741		$ 50,713
Employee Stock Option [Member]
Options Exercised, Issued (in shares)	16,964	[1]	100,422	[2]
Options Exercised, Issuance Value	$ 7,634	[1]	$ 113,539	[2]
Shares Issued Under Stock Incentive Plan [Member]
Shares Issued Under Stock Incentive Plan, Issued (in shares)	223,156		141,546
Shares Issued Under Stock Incentive Plan, Issuance Value	$ 290,237		$ 239,255
Minimum [Member] | October 2018 Warrants [Member]
Equity Financing, Value per Share (in dollars per share)			$ 1.20
Consulting Services, Value per Share (in dollars per share)			1.20
Minimum [Member] | Stock Issued for Consulting Services [Member]
Equity Financing, Value per Share (in dollars per share)	$ 1.26		1.61		$ 1.26
Consulting Services, Value per Share (in dollars per share)	1.26		1.61		1.26
Minimum [Member] | Employee Stock Option [Member]
Equity Financing, Value per Share (in dollars per share)	0.45	[1]	0.93	[2]	0.45	[1]
Consulting Services, Value per Share (in dollars per share)	0.45	[1]	0.93	[2]	0.45	[1]
Minimum [Member] | Shares Issued Under Stock Incentive Plan [Member]
Equity Financing, Value per Share (in dollars per share)	1.25		1.65		1.25
Consulting Services, Value per Share (in dollars per share)	1.25		1.65		1.25
Maximum [Member] | October 2018 Warrants [Member]
Equity Financing, Value per Share (in dollars per share)			1.35
Consulting Services, Value per Share (in dollars per share)			1.35
Maximum [Member] | Stock Issued for Consulting Services [Member]
Equity Financing, Value per Share (in dollars per share)	1.42		1.77		1.42
Consulting Services, Value per Share (in dollars per share)	1.42		1.77		1.42
Maximum [Member] | Employee Stock Option [Member]
Equity Financing, Value per Share (in dollars per share)	0.45	[1]	1.32	[2]	0.45	[1]
Consulting Services, Value per Share (in dollars per share)	0.45	[1]	1.32	[2]	0.45	[1]
Maximum [Member] | Shares Issued Under Stock Incentive Plan [Member]
Equity Financing, Value per Share (in dollars per share)	1.33		1.72		1.33
Consulting Services, Value per Share (in dollars per share)	$ 1.33		$ 1.72		1.33
The 2018 October Offering [Member]
Stock Issued During Period, Shares, New Issues			12,613,049
Stock Issued During Period, Value, New Issues			$ 20,180,878
The 2018 October Offering [Member] | Minimum [Member]
Equity Financing, Value per Share (in dollars per share)			$ 1.60
Consulting Services, Value per Share (in dollars per share)			1.60
The 2018 October Offering [Member] | Maximum [Member]
Equity Financing, Value per Share (in dollars per share)			1.60
Consulting Services, Value per Share (in dollars per share)			$ 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]
Equity Financing, Value per Share (in dollars per share)	$ 1.19				1.19
Consulting Services, Value per Share (in dollars per share)	1.19				1.19
Shares Issued for Credit Facility [Member] | Maximum [Member]
Equity Financing, Value per Share (in dollars per share)	1.19				1.19
Consulting Services, Value per Share (in dollars per share)	$ 1.19				$ 1.19

[1] 25,000 stock options were exercised on a forfeiture basis, resulting in 16,964 net shares being issued.

[2] 117,250 stock options were exercised on a forfeiture basis, resulting in 34,172 net shares being issued.