Summary of Significant Accounting Policies (Details)		1 Months Ended	3 Months Ended			9 Months Ended	12 Months Ended
	Feb. 12, 2020 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($) segment shares	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($) shares	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		$ 14,694,000	$ 9,500,000			$ 9,500,000	$ 14,694,000	$ 2,875,000
Provision for doubtful accounts		$ 110,000	48,000		$ 0	48,000	110,000	0
Goodwill impairment charges			0				0	0
Impairment of intangible assets			0				0	0
Revenue from product and license fees			2,425,000		1,100,000		11,371,000	11,934,000
Term of cooperation and development agreement.		3 years
Revenue recognized for collaboration development activities			333,000				333,000
Deferred revenue		$ 674,000	505,000			505,000	674,000	0
Cumulative effect of government rate change			(83,000)	$ 505,000		423,000
Grant reimbursement			$ 42,000		$ 72,000		$ 426,000	$ 0
Number of anti-dilutive shares (in shares) | shares			3,637,937		2,473,552		3,285,058	26,422,608
Number of reportable segments | segment			1
Yaskawa
Cash and Cash Equivalents [Line Items]
Letter of intent for development activities	$ 4,000,000.0	4,000,000.0
Proceeds from collaborators		1,000,000.0
Revenue recognized for collaboration development activities			$ 333,000				$ 333,000
Deferred revenue		667,000	334,000			334,000	667,000
Other Assets
Cash and Cash Equivalents [Line Items]
Restricted cash		75,000	$ 75,000			75,000	75,000	$ 75,000
License and Service
Cash and Cash Equivalents [Line Items]
Revenue from product and license fees							$ 5,000,000.0	6,000,000.0	$ 3,000,000.0
Recognition of contractual income								$ 9,000,000.0
Stock options
Cash and Cash Equivalents [Line Items]
Number of anti-dilutive shares (in shares) | shares			2,543,125		2,458,091		2,320,318	2,473,198
Convertible Preferred Stock
Cash and Cash Equivalents [Line Items]
Number of anti-dilutive shares (in shares) | shares								23,933,949
Warrant
Cash and Cash Equivalents [Line Items]
Number of anti-dilutive shares (in shares) | shares			159,415		15,461		159,415	15,461
Restricted Stock Awards (RSA)
Cash and Cash Equivalents [Line Items]
Number of anti-dilutive shares (in shares) | shares			935,397				805,325
Minimum
Cash and Cash Equivalents [Line Items]
Property and equipment, estimated useful life			3 years
Intangible assets, estimated useful life			3 years
Award vesting period			1 year
Maximum
Cash and Cash Equivalents [Line Items]
Property and equipment, estimated useful life			7 years
Intangible assets, estimated useful life			10 years
Award vesting period			4 years
JAPAN
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		$ 42,000	$ 444,000			$ 444,000	$ 42,000	$ 55,000
Percentage of cash and cash equivalents in foreign subsidiary		0.30%	4.70%			4.70%	0.30%	1.90%
Revenue from product and license fees			$ 449,000		$ 11,000		$ 713,000	$ 28,000
UNITED STATES
Cash and Cash Equivalents [Line Items]
Revenue from product and license fees			$ 2,000,000.0		$ 1,100,000		$ 10,700,000	$ 11,900,000