Note 9 - Options and Warrants to Purchase Common Stock (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2018

Dec. 31, 2017

Notes Tables

Schedule of Warrants or Rights [Table Text Block]

	Shares Issuable upon exercise of
	upon Exercise of			Weighted Average
	Outstanding Warrants			Exercise Price
Outstanding at January 1, 2018		18,813,373		$	0.14
Issued		8,000,000		$	0.15
Exercised		(2,000,000	)	$	0.04
Forfeited		--			--
Outstanding at June 30, 2018		24,813,373		$	0.15

	December 31, 2017					December 31, 2016
	Shares issuable upon exercise of			Weighted Average		Shares issuable upon exercise of		Weighted Average
	Outstanding Warrants			Exercise Price		Outstanding Warrants		Exercise Price
Outstanding at beginning of year		3,744,623		$	0.36		461,340	$	1.15
Issued		18,193,750			0.07		3,283,283		0.25
Exercised		(3,125,000	)		0.04		--		--
Forfeited		--					--		--
Outstanding at end of year		18,813,373			0.14		3,744,623		0.36

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

		Warrants Outstanding and Exercisable
		Shares Issuable		Weighted Average
		upon Exercise of		Remaining		Weighted Average
Exercise Price		Outstanding Warrants		Contractual Life (years)		Exercise Price
$	1.15		461,340		2.8	$	1.15
$	0.25		3,283,283		3.0	$	0.25
$	0.04		2,068,750		4.3	$	0.04
$	0.10		11,000,000		4.5	$	0.10
$	0.15		8,000,000		3.0	$	0.15
			24,813,373		5.2	$	0.15

		Warrants Outstanding and Exercisable
Exercise Price		Shares issuable upon exercise of Outstanding Warrants		Weighted Average Remaining Contractual Life (years)		Weighted Average Exercise Price
$	1.15		461,340		3.3	$	1.15
$	0.25		3,283,283		3.5	$	0.25
$	0.04		4,068,750		4.7	$	0.04
$	0.10		11,000,000		5.0	$	0.10
			18,813,373		4.6	$	0.14

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

Dividend Yield		0%
Expected Life (in years)	2.48	–	2.96
Expected Volatility	163.73%	–	177.59%
Risk Free Interest Rate	2.54%	–	2.62%

	2017			2016
Dividend Yield		0%			0%
Expected Life (in years)	2.50	–	6.27	2.00	–	9.02
Expected Volatility	114.98	–	167.28%	65.49	–	65.49%
Risk Free Interest Rate	1.38	–	2.26%	0.76	–	1.78%

Share-based Compensation, Stock Options, Activity [Table Text Block]

	Shares Issuable			Weighted
	Upon Exercise of			Average
	Options			Exercise Price
Outstanding at December 31, 2017		57,057,768		$	0.36
Granted		4,224,999		$	0.11
Exercised		--			--
Forfeited		(232,645	)		1.36
Outstanding at June 30, 2018		61,050,122		$	0.34

	December 31, 2017					December 31, 2016
				Weighted					Weighted
				Average					Average
	Shares			Exercise Price		Shares			Exercise Price
Outstanding at beginning of year		21,277,479		$	0.87		17,806,472		$	1.00
Granted		35,810,289		$	0.06		3,771,488			0.24
Exercised		--			--		--			--
Forfeited		(30,000	)				(300,481	)		0.83
Outstanding at end of year		57,057,768		$	0.36		21,277,479		$	0.87

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

Options Outstanding					Options Exercisable
Number Outstanding	Weighted Average Remaining Contractual Life (years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
35,322,222		9.34	$	0.06		26,697,225	$	0.06
545,289		9.48	$	0.075		408,968	$	0.075
377,777		4.93	$	0.11		69,444	$	0.11
3,000,000		4.61	$	0.12		1,000,000	$	0.12
500,000		3.13	$	0.16		500,000	$	0.16
81,395		5.64	$	0.21		81,395	$	0.21
100,000		2.22	$	0.22		100,000	$	0.22
1,066,155		2.87	$	0.24		1,066,155	$	0.24
2,087,500		4.29	$	0.25		2,087,500	$	0.25
35,595		4.79	$	0.27		35,595	$	0.27
474,815		5.86	$	0.28		474,815	$	0.28
234,506		4.64	$	0.285		234,506	$	0.285
81,522		2.56	$	0.30		81,522	$	0.30
200,000		6.63	$	0.66		200,000	$	0.66
150,000		6.61	$	0.68		150,000	$	0.68
7,233,277		0.50	$	0.70		7,233,277	$	0.70
488,356		6.89	$	0.73		488,356	$	0.73
3,104,653		3.65	$	0.83		3,104,653	$	0.83
975,000		5.95	$	0.84		975,000	$	0.84
300,000		5.14	$	1.10		300,000	$	1.10
300,000		4.99	$	1.15		300,000	$	1.15
115,000		2.74	$	1.35		115,000	$	1.35
300,000		3.90	$	1.55		300,000	$	1.55
3,077,060		4.39	$	1.66		3,077,060	$	1.66
900,000		3.14	$	1.90		900,000	$	1.90
61,050,122		6.82	$	0.34		49,980,471	$	0.40

Options Outstanding					Options Exercisable
	Weighted
	Average		Weighted				Weighted
	Remaining		Average				Average
Number	Contractual		Exercise		Number		Exercise
Outstanding	Life (years)		Price		Exercisable		Price
34,475,000		9.95	$	0.06		15,568,718	$	0.06
545,289		9.98	$	0.075		45,289	$	0.075
500,000		3.62	$	0.16		500,000	$	0.16
81,395		6.14	$	0.21		40,698	$	0.21
100,000		2.71	$	0.22		100,000	$	0.22
1,066,155		3.36	$	0.24		1,066,155	$	0.24
2,087,500		4.79	$	0.25		2,087,500	$	0.25
35,595		5.29	$	0.27		17,798	$	0.27
474,815		6.36	$	0.28		362,408	$	0.28
234,506		5.13	$	0.285		234,506	$	0.285
81,522		3.05	$	0.30		40,716	$	0.30
200,000		7.12	$	0.66		200,000	$	0.66
150,000		7.10	$	0.68		99,990	$	0.68
7,233,277		0.99	$	0.70		7,233,277	$	0.70
488,356		7.38	$	0.73		371,666	$	0.73
3,104,653		4.15	$	0.83		3,104,653	$	0.83
975,000		6.45	$	0.84		975,000	$	0.84
300,000		5.64	$	1.10		300,000	$	1.10
300,000		5.48	$	1.15		300,000	$	1.15
100,000		0.08	$	1.24		100,000	$	1.24
115,000		3.24	$	1.35		115,000	$	1.35
125,000		0.08	$	1.45		125,000	$	1.45
300,000		4.40	$	1.55		300,000	$	1.55
7,645		0.09	$	1.58		7,645	$	1.58
3,077,060		4.89	$	1.66		3,077,060	$	1.66
900,000		3.63	$	1.90		900,000	$	1.90
57,057,768		7.45	$	0.36		37,273,079	$	0.52