The Company periodically issues stock options and warrants to employees and non-employees in capital raising transactions, for services and for financing costs.  Options vest and expire according to terms established at the grant date.

Options 

Employee options vest according to the terms of the specific grant and expire from 2 to 10 years from date of grant. The weighted-average, remaining contractual life of employee and non-employee options outstanding at March 31, 2016 was 5.4 years. Stock option activity for the period January 1, 2016 up to March 31, 2016, was as follows: 

The weighted average exercise prices, remaining contractual lives for options granted, exercisable, and expected to vest as of March 31, 2016 were as follows:

During the three-month period ending March 31, 2016 the Company granted options to purchase 1,710,527 shares of common stock to members of the Company’s Board of Directors. The options are exercisable at $0.19 per share, vest monthly over a twelve-month period, and expire ten years from the date granted. Total fair value of these options at grant date was $273,683 using the Black-Scholes Option Pricing model with the following assumptions: life of 5.5 years; risk free interest rate of 1.73%; volatility of 119% and dividend yield of 0%.

During the three month periods ended March 31, 2016 and 2015, the Company recognized compensation costs based on the fair value of options that vested of $99,595 and $207,425 respectively.

At March 31, 2016, the Company’s closing stock price was $0.15 per share. As all outstanding options had an exercise price greater than $0.15 per share, the aggregate intrinsic value of the options outstanding at March 31, 2016 was $0. Future unamortized compensation expense on the unvested outstanding options at March 31, 2016 is $207,815 to be recognized through December 2016.

Warrants

The following table summarizes certain information about the Company’s stock purchase warrants activity for the period starting January 1, 2016 up to March 31, 2016.

The weighted average exercise prices, remaining contractual lives for warrants granted, exercisable, and expected to vest as of March 31, 2016 were as follows:

In the three-month period ending March 31, 2016, pursuant to terms of convertible notes issued, the Company granted warrants to purchase 4,193,575 shares of common stock with an exercise price of $0.10 per share, vesting immediately upon grant and expiring one year from the date of grant (see Note 5).

During the three-month period ending March 31, 2016 the Company granted warrants to purchase 400,000 shares of common stock to consultants. The options are exercisable starting at $0.12 per share to $0.18 per share, vested upon issuance, and expire one year from the date granted.

During the three periods ended March 31, 2016 and 2015, the Company recognized compensation costs of $27,660 and $20,927, respectively, based on the fair value of warrants that vested. Total fair value of these warrants at March 31, 2016 was computed using the Black-Scholes Option Pricing model with the following assumptions: life of 1 year and 8 years; average stock price of $0.16 per share, average risk free interest rate of 0.83%; average volatility of 110% and dividend yield of 0%.

At March 31, 2016, the aggregate intrinsic value of the warrants outstanding was $256,679. Future unamortized compensation expense on the unvested outstanding warrants at March 31, 2016 is approximately $475 to be recognized through April 2016.