Prepaid expenses

12 Months Ended

Dec. 31, 2018

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Prepaid expenses

6. Prepaid expenses 

Prepaid expenses consist of the following: 

	December 31,
	2018		2017
Director compensation	$	100	$	66
Director, officer and other insurance		121		33
Marketing programs and conferences		53		—
Legal retainer		25		25
Inventory purchase deposits		—		20
Professional service retainer		8		8
Rent		19		—
Equipment service deposits		3		7
Engineering, software licenses and other		13		11
Total prepaid expenses	$	342	$	170