Assumptions used in the Black-Scholes valuation model (Details)

12 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Assumptions used in the Black-Scholes valuation model

Stock price over the period

0.17 – 0.23

0.20 –0.94

Risk free interest rate

0.13 to 0.25%

0.09 to 0.16%

Expected life of short-term notes payable

9 to 14 months

8 to 12 months

Expected volatility

95.24-119.45%

114.14%

Expected dividend rate

0.00%

0.00%