Microbot Medical (MBOT) S-3 Shelf registration

Exhibit 12.1

StemCells, Inc
Ratio of earnings to fixed charges
September 30, 2010

																Nine Months Ended
	2005			2006			2007			2008			2009			9/30/2010
Earnings:
Income (loss) from from continuing operations before income taxes	$	(11,738	)	$	(18,948	)	$	(25,023	)	$	(29,087	)	$	(27,026	)	$	(16,287	)
Add (deduct):
Fixed charges		994			990			1,042			1,110			1,065			912
Adjusted earnings		(12,732	)		(19,938	)		(26,065	)		(30,197	)		(28,091	)		(17,198	)
Fixed Charges:
Interest expense		172			143			124			110			111			73
Estimate of the interest within rental expense		822			847			918			1,000			954			839
Total fixed charges		994			990			1,042			1,110			1,065			912
Excess (deficiency) of earnings available to fixed charges	$	(13,726	)	$	(20,927	)	$	(27,107	)	$	(31,307	)	$	(29,156	)	$	(18,110	)
Ratio of earnings to fixed charges*		N/A			N/A			N/A			N/A			N/A			N/A

* Our earnings were insufficient to cover fixed charges in each of the years in the five-year period ended December 31, 2009 and for the nine-month period ended September30, 2010 and accordingly ratios are not presented.

StemCells, Inc.
Estimate of Interest within Rental Expense
September 30, 2010

	Year ended December 31,										Nine Months Ended
	2005		2006		2007		2008		2009		9/30/2010
Rent Expense, net	$	2,021,122	$	2,351,311	$	2,471,033	$	2,268,365	$	2,444,993	$	2,417,393
Adj. Rent Expense, net	$	2,021,122	$	2,351,311	$	2,471,033	$	2,268,365	$	2,444,993	$	2,417,393
Interest Portion (1)	$	821,780	$	846,594	$	918,240	$	1,000,043	$	953,868	$	838,966

(1) The interest portion of rental expense represents an interest factor derived from our Rhode Island bond obligations (as calculated below), which is deemed representative of the interest portion of rental expense

			Avg. Loan		Principal		Interest		Total		Interest
Interest Factor — Bonds	Loan Balance		Balance		Amount Paid		Expense		Payment		Factor			check
2004		1,849,583
2005		1,605,417		1,727,500		244,167		167,301		411,468		40.7	%		—
2006		1,351,250		1,478,333		254,167		143,001		397,168		36.0	%		—
2007		1,145,416		1,248,333		205,833		121,719		327,552		37.2	%		—
2008		1,009,166		1,077,291		136,250		107,430		243,680		44.1	%		0
2009		860,000		934,583		149,166		95,421		244,587		39.0	%		—
2010		741,250		800,625		118,750		63,118		181,868		34.7	%		—
						1,108,333		697,990		1,806,323		38.6	%