Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2016

A summary of option transactions for all of the Company's stock options during the years ended December 31, 2016 and 2015 follows:

	Number of Stock Options			Weighted Average Exercise Price
Outstanding at December 31, 2014		1,308,835		$	2.76
Granted		1,487,500			1.15
Exercised		-			-
Expired/cancelled		(111,983	)		10.70
Outstanding at December 31, 2015		2,684,352			1.54
Granted		2,340,000			0.58
Exercised		-			-
Expired/cancelled		(523,830	)		2.07
Outstanding at December 31, 2016		4,500,522		$	1.02
Exercisable at December 31, 2016		2,200,672		$	1.48
Options expected to vest at December 31, 2016		2,049,850		$	0.59

Schedule of Stock Options Outstanding

The outstanding and exercisable options at December 31, 2016, have a range of exercise prices and associated weighted remaining contractual life and weighted average exercise price, as follows:

Options Range of Exercise Prices		Outstanding Number of Shares		Weighted Average Remaining Contractual Life (years)		Weighted Average Exercise Price		Exercisable Number of Shares		Exercisable Weighted Avg. Exercise Price
$	0 - $1.25		3,827,500		9.41	$	0.80		1,530,000	$	1.14
$	1.26 - $5.00		625,000		7.93		1.58		625,000		1.58
$	5.01 - $10.00		36,022		6.78		7.06		34,597		7.08
$	10.01 - $63.00		12,000		5.60		24.19		11,075		24.27
Total			4,500,522		9.17	$	1.02		2,200,672	$	1.48

Schedule of Fair Value of Each Option Award Granted

The fair value of each option award granted during the period is estimated on the date of grant using the Black-Scholes option valuation model and assumptions as noted in the following table:

	Years Ended December 31,
	2016	2015
Risk-free interest rate	1.51 – 2.18%	1.80 - 1.90%
Volatility	50.00%	50.00 - 85.68%
Expected dividend yield	0%	0%
Expected life	6.5 years	6.5 years
Estimated forfeiture rate	0%	0%