Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Jun. 30, 2022
Current assets
Cash and cash equivalents	$ 14,435	$ 26,453	[1]
Short-term investments	29,714	26,173	[1]
Accounts receivable	74	56	[1]
Cost and estimated revenue in excess of billings	0	2	[1]
Inventory, net:
Raw materials	1,242	864	[1]
Work-in-process	63	136	[1]
Finished goods	452	518	[1]
Prepaid expenses and other current assets	930	748	[1]
Total current assets	46,910	54,950	[1]
Property and equipment, net	2,169	1,098	[1]
Operating leases, right-of-use assets, net	299	162	[1]
Other assets, net	30	11	[1]
Total assets	49,408	56,221	[1]
Current liabilities
Accounts payable	274	169	[1]
Payroll related accruals	922	816	[1]
Accrued expenses and other liabilities	833	961	[1]
Income tax payable	0	2	[1]
Lease liabilities, current	295	234	[1]
Total current liabilities	2,324	2,682	[1]
Lease liabilities, net of current portion	281	303	[1]
Total liabilities	2,605	2,985	[1]
Commitments and contingencies (Note 13)
Stockholders’ equity
Convertible preferred stock, $0.001 par value, 2,500,000 shares authorized; 280,898 shares of Series D issued and outstanding at March 31, 2023 and June 30, 2022	0	0	[1]
Common stock, $0.001 par value, 250,000,000 shares authorized at March 31, 2023 and June 30, 2022; 1,692,600 and 1,685,595 shares issued at March 31, 2023 and June 30, 2022, respectively; 1,686,723 and 1,685,595 outstanding at March 31, 2023 and June 30, 2022, respectively	190,643	190,642
Treasury shares, 5,821 and no shares at March 31, 2023 and June 30, 2022, respectively	(69)	0
Additional paid-in capital	80,651	79,505	[1]
Accumulated deficit	(223,034)	(215,712)	[1]
Accumulated other comprehensive loss	(1,388)	(1,199)	[1]
Total stockholders’ equity	46,803	53,236	[1]
Total liabilities and stockholders’ equity	49,408	56,221	[1]
Related Party [Member]
Current liabilities
Term note payable - related party	$ 0	$ 500	[1]

[1] The balance sheet at June 30, 2022, has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by the United States generally accepted accounting principles for complete financial statements.