Unaudited Condensed Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ 336,443	$ (1,105,791)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation	177,388	121,417
Amortization	163,763	169,346
Amortization of discounts on investments, net	(81,770)	(8,280)
Stock-based compensation	514,266	358,896
Deferred tax liability	5,634	2,592
Changes in operating assets and liabilities:
Trade accounts receivable	(967,411)	238,085
Inventory	68,044	222,869
Prepaid expenses and other assets	76,815	(510,637)
Accounts payable	503,679	246,723
Accrued bonus	(1,612,383)	(1,505,593)
Accrued liabilities	(18,989)	(40,555)
Deferred obligation under operating lease	(40,442)	(15,678)
Net cash used in operating activities	(874,963)	(1,826,606)
Cash flows from investing activities:
Purchases of available-for-sale securities	(10,461,995)	(3,724,200)
Maturities of available-for-sale securities	9,585,247	7,500,000
Purchases of property and equipment	(159,126)	(503,214)
Net cash provided by (used in) investing activities	(1,035,874)	3,272,586
Cash flows from financing activities:
Repayment of notes payable		(333,333)
Common stock repurchases	(193,278)	(779,913)
Proceeds from exercise of stock options	230,879	103,705
Net cash provided by (used in) financing activities	37,601	(1,009,541)
Net increase (decrease) in cash and cash equivalents	(1,873,236)	436,439
Cash and cash equivalents, beginning of period	13,620,656	15,026,068
Cash and cash equivalents, end of period	11,747,420	15,462,507
Supplemental disclosure of cash flow information
Interest paid	600	15,340
Taxes paid	$ 20,894	$ 7,409