Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (42,854,000)	$ (92,493,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	7,258,000	31,402,000
Depreciation and amortization	3,074,000	2,992,000
Change in allowance for doubtful accounts	148,000	26,000
Change in fair value of common stock warrant liability	(2,914,000)
Amortization of intangible assets	189,000	193,000
Amortization of debt discount	19,000	49,000
Change in fair value of contingent consideration		(36,000)
Loss on abandonment of property and equipment and ROU assets	2,806,000	914,000
Other non-cash adjustments	(21,000)	20,000
Changes in operating assets and liabilities:
Accounts receivable	(2,236,000)	(1,045,000)
Inventory	(631,000)	84,000
Prepaid expenses and other current assets	272,000	193,000
Operating lease right-of-use assets	1,700,000	1,651,000
Other assets/liabilities, net	(200,000)	(249,000)
Accounts payable and accrued expenses	(2,761,000)	1,269,000
Other current liabilities	35,000	32,000
Deferred revenue	70,000	(72,000)
Operating lease liabilities	(1,708,000)	(1,578,000)
Net cash used in operating activities	(37,754,000)	(56,648,000)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of property and equipment	(1,339,000)	(2,773,000)
Purchase of available-for-sale securities	(14,144,000)	(40,072,000)
Proceeds from maturities of available-for-sale securities	16,945,000	23,327,000
Proceeds from sale of available-for-sale securities	16,171,000	3,901,000
Net cash provided by/(used in) investing activities	17,633,000	(15,617,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from term note payable and financing arrangements	4,629,000
Principal payments on term note payable and financing arrangements	(1,675,000)	(534,000)
Payment of contingent consideration liability		(225,000)
Principal payments on financing leases	(508,000)	(453,000)
Net proceeds from the sale of common stock, warrants and pre-funded warrants	32,020,000	28,073,000
Proceeds from warrants exercised	1,008,000
Cash paid for tax withholdings related to net share settlement	(155,000)	(679,000)
Proceeds from stock options exercised	31,000	529,000
Proceeds from ESPP purchase	75,000	99,000
Net cash provided by financing activities	35,425,000	26,810,000
Net increase/(decrease) in cash and cash equivalents	15,304,000	(45,455,000)
Cash and cash equivalents - beginning of period	10,218,000	55,673,000
Cash and cash equivalents - end of period	25,522,000	10,218,000
Supplemental cash flow information:
Cash paid for interest	187,000	199,000
Supplemental schedule of non-cash investing and financing activities:
Property and equipment additions acquired through finance leases		2,578,000
Property and equipment acquired through financing arrangements		58,000
Unpaid liability for acquisition of property and equipment	87,000	273,000
Reclassification of stock-based compensation expense that was previously classified as a liability to paid-in capital		38,000
Right-of-use asset obtained in exchange for new lease liability	82,000
Allocation of proceeds from sale of common stock and warrants to warrant liability	17,154,000
Reclassification of warrant liability to stockholders’ equity upon exercise of warrant	$ 8,265,000