Exhibit 10.1

 

JOINDER AGREEMENT

TO

STOCK PURCHASE AGREEMENT

 

Optical Sensors Incorporated, a Delaware corporation d/b/a väsamed, with its
principal place of business at 7615 Golden Triangle Drive, Suite C, Eden
Prairie, Minnesota 55344 (the ”Company”), and Circle F Ventures, LLC, Circle F
Ventures II, LLC and the Hayden R. Fleming and LaDonna M. Fleming Revocable
Trust (the “Circle F Investors”) and Barth Investment Company II, L.P. (the
”Investor”) (the Circle F Investors and Investor, collectively, the “Series C
Investors”) executed a Stock Purchase Agreement (“Stock Purchase Agreement”)
effective as of May 6, 2005.

 

The Investor previously purchased shares of the Company’s Series C Preferred
Stock (as such term is defined in the Stock Purchase Agreement) pursuant to the
Stock Purchase Agreement and now desires to purchase the additional number of
shares of the Company’s Series C Preferred Stock, as set forth on Schedule A-1
attached hereto, at a purchase price of $90.00 per share pursuant to the terms
of the Stock Purchase Agreement.

 

The Company desires to qualify its representations and warranties contained in
Section 4 of the Stock Purchase Agreement pursuant to the Schedule of Exceptions
attached hereto as Schedule B-1 and hereby makes such representations and
warranties as of the date hereof for the benefit of the Investor.

 

The Investor hereby agrees to purchase the number of shares of the Company’s
Series C Preferred Stock set forth on Schedule A-1 at a purchase price of $90.00
per share pursuant to the terms of the Stock Purchase Agreement. The Investor
hereby explicitly affirms and acknowledges the representations and warranties
set forth in Section 5 of the Stock Purchase Agreement.

 

IN WITNESS WHEREOF, the Company and the Investor have executed this Joinder
Agreement effective as of June 15, 2005.

 

OPTICAL SENSORS INCORPORATED By  

/s/ Paulita LaPlante

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    Paulita LaPlante,     President and Chief Executive Officer BARTH INVESTMENT
COMPANY II, LP By  

/s/ Bruce Barth

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Its   General Partner

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SCHEDULE A-1

 

Name of Investor

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   Date of
Investment

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   Amount of
Investment

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   Number of
Shares

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Barth Investment Co. II, LP

10863 East Purple Aster Way

Scottsdale, Arizona 85262

   June 15, 2005    $ 300,000    3,334

Totals:

        $ 300,000    3,334