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Notes Payable (Details Narrative) - USD ($) |  |  |  |  |  |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Aug. 28, 2020 | Jun. 24, 2020 | Jun. 22, 2020 | May 26, 2020 | Apr. 23, 2020 | Jun. 27, 2018 | Dec. 31, 2020 | Dec. 31, 2019 | Sep. 21, 2020 | Aug. 31, 2020 | Feb. 29, 2020
Financing fees and expenses |  |  |  |  |  |  | $ 1,292,338 | $ 1,393,400 |  |  |
Debt financing fees |  |  |  |  |  |  | $ 51,160 |  |  |  |
Warrants exercise per share |  |  |  |  |  |  | $ 0.01 | $ 0.01 | $ 0.79 |  |
Warrants exercisable |  |  |  |  |  |  |  |  | 75,000 | 247,525 | 3,200,000
Loan amount |  |  |  |  |  |  | $ 5,000,000 |  |  |  |
Net proceeds from issuance of common stock |  |  |  |  |  |  | 22,811,669 | $ 7,844,852 |  |  |
Initial Horizon Credit Agreement Amendment [Member] |  |  |  |  |  |  |  |  |  |  |
Interest expense, debt, total |  |  |  |  |  |  | 808,899 | 1,006,760 |  |  |
Amortization of debt issuance costs |  |  |  |  |  |  | 483,439 | $ 386,640 |  |  |
Common Stock Outstanding [Member] |  |  |  |  |  |  |  |  |  |  |
Common stock shares issued |  |  | 2,666,667 |  |  |  |  |  |  |  |
Net proceeds from issuance of common stock |  |  | $ 9,100,000 |  |  |  |  |  |  |  |
Initial Horizon Credit Agreement [Member] |  |  |  |  |  |  |  |  |  |  |
Line of credit facility, maximum borrowing capacity |  |  |  |  |  | $ 10,000,000 |  |  |  |  |
Proceeds from lines of credit, total |  |  |  |  |  | 10,000,000 |  |  |  |  |
Debt instrument, end term fee |  |  |  |  |  | 142,605 |  |  |  |  |
Financing fees and expenses |  |  |  |  |  | 175,000 |  |  |  |  |
Loan origination fees |  |  |  |  |  | 100,000 |  |  |  |  |
Debt instrument, unamortized discount |  |  |  |  |  | $ 782,116 |  |  |  |  |
End of term charge percentage |  |  |  |  |  | 4.00% |  |  |  |  |
Debt financing fees |  |  |  |  |  | $ 400,000 |  |  |  |  |
Fair value of warrants |  |  |  |  |  | 507,116 |  |  |  |  |
End of term fees |  |  |  |  |  | $ 275,000 |  |  |  |  |
Initial Horizon Credit Agreement [Member] | Common Stock Outstanding [Member] |  |  |  |  |  |  |  |  |  |  |
Warrants exercise per share |  |  |  |  |  | $ 2.63 |  |  |  |  |
Warrants exercisable |  |  |  |  |  | 190,114 |  |  |  |  |
Warrants outstanding |  |  |  |  |  | 95,057 |  |  |  |  |
Amendment to Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member] |  |  |  |  |  |  |  |  |  |  |
Repayment of loans | $ 5,000,000 |  |  |  |  |  |  |  |  |  |
Debt instrument related end term charges | 200,000 |  |  |  |  |  |  |  |  |  |
Debt instrument face amount | $ 5,000,000 |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate terms | The obligations bear interest at a rate calculated based an amount by which the one-month LIBOR exceeds 2% plus 7.625%. In no event shall the interest rate be less than 9.625%. Payments pursuant to the Amendment are interest only for the first twelve (12) months after August 1, 2020, followed by a 21-month amortization period of principal and interest through the scheduled maturity date. |  |  |  |  |  |  |  |  |  |
Debt instrument, end term fee | $ 275,000 |  |  |  |  |  |  |  |  |  |
Debt instrument, restrictive covenants | In connection with the Amendment, Celsion agreed to a liquidity covenant which provides that, at all times, Celsion shall maintain unrestricted cash and/or cash equivalents on deposit in accounts over which the applicable Lenders maintain an account control agreement in an amount not less than $2.5 million. In addition, pursuant to the Amendment, Celsion has agreed to provide evidence to Horizon on or before March 31, 2021, that it has received aggregate cash proceeds of not less than $5 million from the sale of equity, debt, its New Jersey net operating losses, or a combination thereof, subsequent to the date of the Amendment. |  |  |  |  |  |  |  |  |  |
Debt instrument, unamortized discount | $ 200,000 |  |  |  |  |  | $ 109,706 |  |  |  |
Debt financing fees | 5,000 |  |  |  |  |  |  |  |  |  |
Payment of debt extinguishment | 5,000,000 |  |  |  |  |  |  |  |  |  |
New warrants fair value | $ 247,548 |  |  |  |  |  |  |  |  |  |
Amendment to Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member] | Common Stock Outstanding [Member] |  |  |  |  |  |  |  |  |  |  |
Warrants exercise per share | $ 1.01 |  |  |  |  |  |  |  |  |  |
Warrants exercisable | 247,525 |  |  |  |  |  |  |  |  |  |
Warrants cancelled | 95,057 |  |  |  |  |  |  |  |  |  |
Amendment to Horizon Credit Agreement [Member] | Horizon Technology Finance Corporation [Member] | One-Month LIBOR Exceeds 2% Plus [Member] |  |  |  |  |  |  |  |  |  |  |
Debt instrument interest rate | 9.625% |  |  |  |  |  |  |  |  |  |
April PPP Loan [Member] | Silicon Valley Bank [Member] |  |  |  |  |  |  |  |  |  |  |
Proceeds from loan |  |  |  |  | $ 632,220 |  |  |  |  |  |
Loan repayment date |  |  |  |  | May 13, 2020 |  |  |  |  |  |
PPP Loans [Member] | Silicon Valley Bank [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |
Loan amount |  |  |  |  | $ 2,000,000 |  |  |  |  |  |
May PPP Loan [Member] |  |  |  |  |  |  |  |  |  |  |
Interest accrued on loan |  | $ 577 |  |  |  |  |  |  |  |  |
May PPP Loan [Member] | Silicon Valley Bank [Member] |  |  |  |  |  |  |  |  |  |  |
Proceeds from loan |  |  |  | $ 692,530 |  |  |  |  |  |  |
Loan repayment date |  |  |  | Jun. 24, 2020 |  |  |  |  |  |  |
May PPP Loan [Member] | Silicon Valley Bank [Member] | Promissory Note [Member] |  |  |  |  |  |  |  |  |  |  |
Debt instrument face amount |  |  |  | $ 692,530 |  |  |  |  |  |  |

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