BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 178,705	$ 22,860
Investments, short-term	55,932	126,605
Accounts receivable, net of allowance for credit losses of $42 and $48, respectively	21,101	13,131
Inventories	8,966	5,834
Prepaid expenses and other current assets	2,219	2,206
Total current assets	266,923	170,636
Investments, long-term	0	6,276
Property and equipment, net	4,309	3,045
Operating lease right-of-use asset	171	915
Other non-current assets	381	381
Total assets	271,784	181,253
Current liabilities:
Accounts payable	6,743	4,459
Accrued expenses	11,455	12,397
Total current liabilities	18,198	16,856
Notes payable	24,689	24,522
Other non-current liability	74	40
Total liabilities	42,961	41,418
Stockholders' equity:
Preferred Stock, $0.001 par value, 10,000,000 shares authorized; no shares issued and outstanding at September 30, 2020 and December 31, 2019	0	0
Common Stock, $0.001 par value per share; 200,000,000 shares authorized; 26,920,845 and 24,107,350 issued and outstanding at September 30, 2020 and December 31, 2019, respectively	27	24
Additional paid-in capital	458,586	319,865
Accumulated other comprehensive income	73	102
Accumulated deficit	(229,863)	(180,156)
Total stockholders' equity	228,823	139,835
Total liabilities and stockholders' equity	$ 271,784	$ 181,253