|
Note 2 - Summary of Significant Accounting Policies (Tables)
|
9 Months Ended |
12 Months Ended |
|
Sep. 30, 2014
|
Dec. 31, 2013
|
| Accounting Policies [Abstract] |
|
|
| Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] |
|
|
|
|
Carrying Values
|
|
|
Estimated
Fair Value
|
|
|
Related party Boston Scientific convertible notes payable
|
|
$
|
4,338,601
|
|
|
$
|
4,000,842
|
|
|
Note payable
|
|
|
3,852,183
|
|
|
|
3,852,183
|
|
|
Junior secured notes payable
|
|
|
232,405
|
|
|
|
2,095,610
|
|
|
| Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] |
|
|
|
Quoted Prices in Active Markets
(Level 1)
|
|
|
Significant
Observable
Inputs (Level 2)
|
|
|
Significant Unobservable
Inputs (Level 3)
|
|
|
Total Fair
Value
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
September 30, 2014
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Derivative liabilities - warrants
|
|
$
|
-
|
|
|
$
|
-
|
|
|
$
|
3,169,679
|
|
|
$
|
3,169,679
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
December 31, 2013
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Derivative liabilities - warrants
|
|
$
|
-
|
|
|
$
|
-
|
|
|
$
|
3,747,858
|
|
|
$
|
3,747,858
|
|
|
|
|
|
Quoted Prices in
Active Markets
(Level 1)
|
|
|
Significant
Observable
Inputs (Level 2)
|
|
|
Significant
Unobservable
Inputs (Level 3)
|
|
|
Total Fair
Value
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
At December 31, 2013:
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Derivative liability - warrants
|
|
$
|
-
|
|
|
$
|
-
|
|
|
$
|
3,747,858
|
|
|
$
|
3,747,858
|
|
|
Derivative liability - conversion option
|
|
|
-
|
|
|
|
-
|
|
|
|
-
|
|
|
|
-
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
At December 31, 2012:
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Derivative liability - warrants
|
|
$
|
-
|
|
|
$
|
-
|
|
|
$
|
2,128,302
|
|
|
$
|
2,128,302
|
|
|
Derivative liability - conversion option
|
|
|
-
|
|
|
|
-
|
|
|
|
789
|
|
|
|
789
|
|
|
| Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] |
|
|
|
As of September 30,
|
|
|
|
|
2014
|
|
|
2013
|
|
|
|
|
|
|
|
|
|
|
|
|
Stock options
|
|
|
7,554,725
|
|
|
|
6,739,877
|
|
|
Warrants
|
|
|
13,327,115
|
|
|
|
12,203,489
|
|
|
Shares under convertible note agreements
|
|
|
-
|
|
|
|
542,325
|
|
|
|
|
|
20,881,840
|
|
|
|
19,485,691
|
|
|
|
|
|
As of December 31,
|
|
|
|
|
2013
|
|
|
2012
|
|
|
|
|
|
|
|
|
|
|
|
|
Stock options
|
|
|
7,430,225
|
|
|
|
6,432,127
|
|
|
Warrants
|
|
|
12,136,865
|
|
|
|
8,763,836
|
|
|
Shares under convertible note agreements
|
|
|
542,325
|
|
|
|
4,454,362
|
|
|
|
|
|
20,109,415
|
|
|
|
19,650,325
|
|
|