| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| ASSETS | | | | | | | | |
| Current Assets: | | | | | | | | |
| Cash and cash equivalents | 11.5 | 6.0 | 0.2 | | 0.0 | 0.1 | 0.1 | 0.3 |
| Trade receivables, net of allowance of $0 and $26,000, respectively | 0.0 | 0.0 | 0.0 | | 0.2 | 0.0 | 0.5 | 2.0 |
| Inventories, net | 0.6 | 0.6 | 0.5 | 0.5 | 0.7 | 1.0 | 2.6 | 4.3 |
| Prepaid and other current assets | 0.3 | 0.2 | 0.1 | 0.1 | 0.1 | 0.5 | 1.0 | 1.4 |
| Total current assets | 12.4 | 6.9 | 0.8 | 0.6 | 1.0 | 1.6 | 4.2 | 8.0 |
| Property, Plant and Equipment: | 22.6 | 22.4 | 24.9 | 32.9 | 36.6 | 36.6 | 36.6 | 37.6 |
| Accumulated depreciation | -22.0 | -22.1 | -24.8 | -28.7 | -32.2 | -32.0 | -31.0 | -28.5 |
| Property, Plant and Equipment, net | 0.6 | 0.3 | 0.0 | 4.2 | 4.4 | 4.6 | 5.7 | 9.1 |
| |
| Other Assets: | | | | | | | | |
| Operating lease right-of-use assets, net | 4.3 | 5.0 | 5.6 | | | | | |
| Patents, net of accumulated amortization of $163,803 and $154,218respectively | 0.1 | 0.1 | 0.4 | 0.8 | 0.9 | 1.5 | 1.6 | 1.6 |
| Equity method investment | 0.1 | 0.0 | | | | | | |
| Other non-current assets | 6.9 | 6.3 | 7.1 | 0.8 | 0.9 | 1.6 | 1.8 | 1.8 |
| Total other assets | 6.9 | 6.3 | 7.1 | 0.8 | 0.9 | 1.6 | 1.8 | 1.8 |
| Total Assets | 18.7 | 12.8 | 7.4 | 5.6 | 6.3 | 7.8 | 11.6 | 18.8 |
| |
| LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) | | | | | | | | |
| Current Liabilities: | | | | | | | | |
| Accounts payable | 0.6 | 0.6 | 0.7 | 1.7 | 2.3 | 1.6 | 4.9 | 3.6 |
| Accrued expenses | 1.0 | 0.7 | 1.5 | 1.6 | 1.6 | 1.2 | 1.5 | 1.7 |
| Accrued professional services fees | 1.0 | 0.1 | | | | | 0.3 | 0.5 |
| Accrued interest | 0.6 | 0.5 | 0.4 | 2.1 | 1.2 | 0.4 | | |
| Current portion of operating lease liability | 0.7 | 0.6 | 0.6 | | | | | |
| Current portion of convertible notes, net | | | | 2.1 | 1.9 | 1.4 | | 0.0 |
| Other payable | 0.3 | 0.3 | | | | | | |
| Total current liabilities | 5.0 | 3.1 | 9.2 | 30.7 | 23.9 | 15.0 | 18.1 | 10.1 |
| |
| Long-Term Liabilities: | | | | | | | | |
| Non-current operating lease liabilities | 3.8 | 4.5 | 5.2 | | | | | |
| Non-current convertible notes, net | 5.3 | 8.1 | 7.8 | | | | | |
| Accrued warranty liability | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 0.2 | 0.3 |
| Total liabilities | 14.1 | 15.7 | 27.6 | 30.7 | 28.9 | 20.2 | | |
| |
| Commitments and contingencies (Note 14) | | | | | | | | |
| Stockholders’ Equity (Deficit): | | | | | | | | |
| Series A preferred stock, $.0001 par value; 750,000 shares authorized; 48,100 and 48,100 shares issued and outstanding, respectively | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | | |
| Common stock | 0.0 | 0.0 | 0.0 | 0.5 | 0.0 | 1.0 | 0.1 | 0.0 |
| Additional paid in capital | 452.1 | 424.9 | 401.6 | 397.8 | 395.9 | 386.3 | 369.9 | 347.6 |
| Accumulated deficit | -447.5 | -427.8 | -421.8 | -423.4 | -418.5 | -402.5 | -383.9 | -345.1 |
| Accumulated other comprehensive loss | 0.0 | | | | | | | |
| Total stockholders’ equity (deficit) | 4.6 | -2.8 | -20.2 | -25.1 | -22.6 | -15.2 | -14.0 | 2.6 |
| Total Liabilities and Stockholders’ Equity (Deficit) | 18.7 | 12.8 | 7.4 | 5.6 | 6.3 | 7.8 | 11.6 | 18.8 |