Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities
Net loss	$ (16,580,237)	$ (14,908,348)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,039,989	920,863
Accretion of discount on NuvoGen obligation	(9,771)	(10,273)
Provision for excess inventory	5,649	126,582
Write-off of Cowen ATM offering costs		108,883
Amortization of QNAH Convertible Note issuance costs	6,505	10,091
Amortization of MidCap Credit Facility discount and issuance costs	101,482	128,476
Amortization of SVB Term Loan discount and issuance costs	121,168
Stock-based compensation expense	1,163,742	845,133
Employee stock purchase plan expense	15,972	49,914
Non-cash operating lease expense	465,504	329,248
Accrued interest on available-for-sale securities investments	(101,996)	(231,272)
Issuance of common stock in connection with LP Purchase Agreement	205,538
Loss on extinguishment of Midcap Credit Facility and QNAH Convertible Note	522,394
Loss on abandonment and disposal of assets, net	77,498
Changes in operating assets and liabilities:
Accounts receivable	1,793,975	1,079,317
Inventory	(255,718)	(11,715)
Prepaid expenses and other	457,504	(383,643)
Deferred offering costs	140,320
Accounts payable	(778,706)	928,454
Accrued liabilities	(474,521)	(1,526,835)
Contract liabilities	(74,700)	152,681
Operating lease liabilities	(583,828)	(446,403)
Net cash used in operating activities	(12,742,237)	(12,838,847)
Investing activities
Purchase of property and equipment	(418,712)	(753,430)
Maturities of available-for-sale securities	25,450,000	30,800,000
Purchase of available-for-sale securities	(11,565,882)	(10,922,764)
Net cash provided by investing activities	13,465,406	19,123,806
Financing activities
Proceeds from issuance of SVB Term Loan and common stock warrants	10,000,000
Payment of SVB Term Loan issuance costs	(115,193)
Proceeds from 2019 underwritten public and private offerings, net of underwriting discounts, commissions and costs of $1.7 million		21,102,077
Proceeds from ATM Offering, net	6,387,982
Proceeds from PPP Loan	1,717,000
Proceeds from Series A convertible preferred stock in private placement	562,955
Payments on NuvoGen obligation	(539,323)	(1,003,634)
Proceeds from exercise of pre-funded warrants	31,768
Proceeds from shares purchased under stock purchase plans	25,133	82,345
Proceeds from exercise of stock options		120,954
Payments on financing leases	(32,553)	(34,928)
Taxes paid for net share settlement of restricted stock awards	(12,824)	(28,067)
Payment of deferred offering costs		(139,058)
Payments on Insurance Note	(324,301)
Net cash provided by financing activities	7,262,021	20,099,689
Effect of exchange rates on cash	9,283	29,838
Increase in cash, cash equivalents and restricted cash	7,994,473	26,414,486
Cash, cash equivalents and restricted cash at beginning of period	10,889,995	11,702,847
Cash, cash equivalents and restricted cash at end of period	18,884,468	38,117,333
Supplemental disclosure of noncash investing and financing activities
Issuance of Series A convertible preferred stock in exchange for outstanding common stock	2,424,900
Issuance of Common stock in exchange for Series A convertible preferred stock	1,622,500
Adoption of ASC 842, Leases		694,352
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	21,078	1,005,085
Carrying value of demonstration units transferred from property and equipment to inventory	18,817
Fixed asset purchases payable and accrued at period end		21,381
Offering costs payable and accrued at period end		276,694
Supplemental cash flow information
Cash paid for interest	719,676	521,538
Cash paid for taxes	9,961	$ 3,170
QNAH Convertible Note
Financing activities
Payments for extinguishment of debt	(3,000,000)
MidCap Credit Facility
Financing activities
Payments for extinguishment of debt	$ (7,438,623)