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Notes Payable and Other Liabilities - Additional Information (Detail)		12 Months Ended
	Jun. 05, 2019 EUR (€)	Dec. 31, 2019 USD ($) FundingArrangement Grant d $ / shares shares	Dec. 31, 2019 EUR (€) FundingArrangement Grant d	Dec. 31, 2018 USD ($)	Dec. 31, 2019 EUR (€) shares	Jun. 29, 2018 USD ($) shares
Debt Instrument [Line Items]
Revenue		$ 5,801,401		$ 10,331,168
Repayments of notes payable		292,002		1,549,702
Economic conditional incentive grants		250,000		100,000
Interest expense		2,244		297,090
Convertible Debt [Member]
Debt Instrument [Line Items]
Convertible note unamortized discount		180,611
Debt issuance costs		58,172
Interest expense				$ 293,009
Additional interest earned		54,226
First Exchange Warrants [Member]
Debt Instrument [Line Items]
Convertible notes principal balance		$ 1,500,000				$ 1,500,000
Shares of common stock called by warrants \| shares		73,530			73,530	53,125
Convertible debt, interest rate in event of default		112.00%	112.00%
Conversion price per share \| $ / shares		$ 20.40
Weighted average prices of common stock		75.00%	75.00%
Weighted average price per share of common stock \| $ / shares		$ 4.50
Number of trading days \| d		20	20
Montgomery County [Member]
Debt Instrument [Line Items]
Expiration date of economic conditional incentive grant		Feb. 28, 2028	Feb. 28, 2028
Accrued interest rate on grant		3.00%	3.00%
State of Maryland [Member]
Debt Instrument [Line Items]
Expiration date of economic conditional incentive grant		Dec. 31, 2029	Dec. 31, 2029
Economic incentive grant term		10 years	10 years
Accrued interest rate on grant		3.00%	3.00%
Montgomery County and State of Maryland [Member]
Debt Instrument [Line Items]
Economic conditional incentive grants		$ 250,000
Number of economic conditional incentive grants \| Grant		2	2
Interest expense		$ 5,042
BPI France Notes [Member]
Debt Instrument [Line Items]
Number of non-interest bearing research and development funding arrangements \| FundingArrangement		2	2
Percentage of fund to be withdrawn upon signing of arrangements		50.00%	50.00%
Additional percentage of fund to be withdrawn, contingent upon financial audit and technical progress report		30.00%	30.00%
Research and development funding arrangements extended period		2 years	2 years
Total long-term debt \| €					€ 500,000
Revenue		$ 265,540	€ 238,229
Paid in excess of allowable funding amount \| €	€ 102,951
Repayments of notes payable		292,002
BPI France Notes [Member] \| Research Funding First Arrangement [Member]
Debt Instrument [Line Items]
Debt instrument, face amount \| €					750,000
BPI France Notes [Member] \| Research Funding Second Arrangement [Member]
Debt Instrument [Line Items]
Debt instrument, face amount \| €					€ 250,000
BPI France Notes [Member] \| Grant [Member]
Debt Instrument [Line Items]
Long-term debt converted amount		$ 265,540	€ 238,229