Note 11 - Warrant Transactions (Tables)

12 Months Ended

Dec. 31, 2013

Warrants [Abstract]

Schedule of Warrant Summary [Table Text Block]

					Weighted-average			Balance sheet
	Warrants as of				exercise			classification
	December 31,		December 31,		price			December 31,
	2013		2012		per share		Expiration	2013	2012
Venture Lending & Leasing VI, Inc.		255,102		-	$	1.96	2/28/2024	Liability	N/A
Venture Lending & Leasing VII, Inc.		255,102		-		1.96	2/28/2024	Liability	N/A
Scott, Richard L. Series #2		-		500,000		2.75	3/21/2016	N/A	Equity
Scott, Richard L. Series #3		-		500,000		2.75	3/21/2016	N/A	Equity
Allen, F. Stephen Series #2		500,000		500,000		3.55	3/21/2016	Equity	Equity
Allen, F. Stephen Series #3		500,000		500,000		3.55	3/21/2016	Equity	Equity
Stearns, Robert		200,000		200,000		3.55	3/21/2016	Equity	Equity
MATT Series #1		401,486		1,000,000		2.75	9/19/2016	Equity	Equity
MATT Series #2		1,000,000		1,000,000		2.75	9/19/2016	Equity	Equity
All warrants		3,111,690		4,200,000

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

Risk-free interest rate:	3.04	%
Expected term (years):	10.17
Expected dividend yield:	—
Expected volatility:	93.15	%

Risk-free interest rate:	2.81	%
Expected term (years):	8.15
Expected dividend yield:	-
Expected volatility:	100.75	%

Risk-free interest rate:	3.24	%
Expected term (years):	6.08
Expected dividend yield:	—
Expected volatility:	94.07	%

Risk-free interest rate:	2.81	%
Expected term (years):	8.73
Expected dividend yield:	-
Expected volatility:	100.75	%

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

Warrants	Number of Warrants			Weighted- Average Exercise Price
Outstanding at December 31, 2012		4,200,000		$	2.98
Granted		510,204		$	1.96
Exercised		(1,002,147	)	$	2.75
Forfeited or expired		(596,367	)	$	2.75
Outstanding at December 31, 2013		3,111,690		$	2.61
Exercisable at December 31, 2013		3,111,690		$	2.61