OPTICAL SENSORS INCORPORATED SELLING AGENCY AGREEMENT

Exhibit 10.30

OPTICAL SENSORS INCORPORATED

SELLING AGENCY AGREEMENT

17797 North Perimeter Drive, Suite 105

Scottsdale, Arizona 85255

Gentlemen:

The undersigned, OPTICAL SENSORS INCORPORATED d/b/a väsamed, a Delaware corporation with its principal office located at 7615 Golden Triangle Drive, Suite C, Eden Prairie, Minnesota 55344 (the “Company”), confirms its agreement with you as follows:

1. Description of Securities and Offering.

(a) The Company proposes to issue and sell in a private placement solely to accredited investors, as such term is defined in Rule 501(a) promulgated under the Securities Act of a 1933, as amended (“1933 Act”) (“Purchasers”), a series of convertible promissory notes in the aggregate principal amount of $4,500,000 (the “Notes”) with detachable warrants (the “Warrants”), the Notes and Warrants, collectively, being referred to herein as (the “Securities”). The Securities will be sold pursuant the terms of a Note and Warrant Purchase Agreement between the Company and each Purchaser in the form annexed hereto as Exhibit “A” (the “Purchase Agreement”). The minimum investment is $100,000, although the Company reserves the right to accept purchases of Securities for such lesser amounts as it may determine in its sole discretion. The Notes are convertible into shares of the Company’s Series C Preferred stock (“Series C Stock”) at a conversion price of $90.00 per share. Each share of Series C Stock by its terms is initially convertible into 40 shares of the Company’s common stock at a conversion price of $2.25 per share. The initial Warrant exercise price is $2.25 per share and is subject to adjustment if the Company issues securities at a price of less than $2.25 per share, subject to customary exceptions, as set forth in the Warrant. The Warrants are exercisable for a period of five years from the date of issuance. The Purchasers are also entitled to demand and piggyback registration rights with respect to the shares of Common Stock underlying the Series C Preferred Stock issuable upon conversion of the Note and the Common Stock issuable upon exercise of the Warrants.

(b) You have advised the Company that Fleming Securities, Inc. (“Fleming Securities” or “Agent”) will act as exclusive agent for the Company for the offering of the Securities. You will offer the Securities on a “best efforts” basis. The Company shall accept or reject a Purchase Agreement signed by a Purchaser and the funding offered thereby as such agreement is presented to

the Company by Agent up to the aggregate principal amount of $4,500,000. The Company retains the right to reject any Purchase Agreement in whole or in part in its reasonable discretion. Each acceptance by the Company will constitute a closing on the accepted Purchase Agreement, and the Company shall promptly issue to the Purchaser a Note and Warrant pursuant to the Purchase Agreement. A final closing shall be held no later than seven (7) business days after termination of the private placement of the Securities for the purpose of closing any remaining sales, paying commissions and expenses to Agent and issuing Placement Agent’s Warrants, as set forth below (the “Closing Date”, and on such date the final “Closing” shall occur). You are authorized to offer the Securities until and including April 6, 2006, which period may be extended for thirty (30) days upon written request to the Company or additional periods as mutually agreed to by the Agent and the Company. The term “Offering Period,” as used herein, shall include the entire period during which the Securities may be offered.

In addition, upon the final Closing Date, the Company agrees to sell to Fleming Securities for an aggregate price of $100, warrants (“Placement Agent’s Warrants”) for the purchase of that number of shares of Common Stock that is equal to 10% of the number of shares of Common Stock that may be purchased pursuant to warrants sold in this bridge financing pursuant to the Purchase Agreement (“Placement Agent’s Shares”). The Placement Agent’s Warrants will be exercisable at a price of $2.70 per Placement Agent’s Share for a period of ten (10) years commencing as of the final Closing Date, such price being adjustable as provided in the Placement Agent’s Warrants which shall be in the form attached hereto as Exhibit “B.”

2. Representations, Warranties and Agreements of the Company. The Company represents, warrants to and agrees with you that:

(a) Applications or other filings necessary to qualify the Securities for sale or to obtain a valid exemption from qualification in the states set forth in Schedule 2(b) or as you may reasonably designate from time to time (the “Designated States”), including an exemption from federal securities laws, have been or will be timely filed to permit the lawful offer and sale of the Securities in such states. These applications or other filings, as they may be amended from time to time, are referred to herein as the “Blue Sky Applications”. The Blue Sky Applications shall be prepared and filed by Company counsel and will be accomplished in a timely manner. The Company shall timely prepare and file a Form D in connection with the offering contemplated hereby.

(b) The Company knows of no outstanding claims for services either in the nature of a finder’s fee or origination fee with respect to the sale of the Securities hereunder resulting from its acts for which you or the Company may be responsible.

(c) This Agreement has been duly authorized by all necessary corporate action of the Company and, when executed and delivered, will be a legal, valid and binding obligation of the Company, enforceable in accordance with its terms, except to the extent that the enforceability hereof may be limited by bankruptcy, insolvency, moratorium or similar laws affecting creditors’ rights generally or by general principles of equity, and except that the indemnification provisions of the Agreement may be held to be in violation of public policy under either federal or state laws in the context of the offer or sale of securities.

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(d) The Securities to be sold by the Company hereunder have been duly authorized. The Securities, when issued and delivered pursuant to this Agreement, will be validly issued and delivered pursuant to this Agreement and will be valid and binding obligations of the Company, enforceable in accordance with their terms. A sufficient number of shares of the Series C Stock and Common Stock of the Company have been reserved for issuance of all shares of Series C Stock and Common Stock that may be issued upon the conversion of the Note, the Series C Stock and upon the exercise of the Warrants and Placement Agent’s Warrants. Upon payment for, and delivery of, the Securities pursuant to the Purchase Agreement, the Purchasers will acquire good and marketable title to the Securities, free and clear of all liens, encumbrances or claims, except those created by the Purchasers.

(e) The Placement Agent’s Warrants and the Placement Agent’s Shares to be issued upon exercise of the Placement Agent’s Warrants, when issued and delivered to you, will constitute valid and binding obligations of the Company in accordance with their terms. All Placement Agent’s Shares issuable upon exercise of the Placement Agent’s Warrants, when issued in accordance with the terms of this Agreement upon the due exercise of the Placement Agent’s Warrants, will be fully paid and non-assessable, and subject to no preemptive rights or similar rights on the part of any person or entity.

(f) Neither the Company nor any affiliate has offered to sell, offered for sale or sold any securities, the offer to sell, offer for sale or sale of which would be integrated (as that term is used in Rule 502(a) of Regulation D promulgated under the 1933 Act (“Regulation D”)) with the offers to sell, offers for sale and sales of the Securities so as to render the exemption upon which the Company is relying in connection with the sale of Securities unavailable with respect to the offering of the Securities hereunder.

(g) The Company will perform its obligations with respect to the offering in a manner intended to be in compliance with the requirements of Regulation D. The Company is not disqualified from claiming exemption under Regulation D by Rule 505(b)(2)(iii) of Regulation D and the offering meets the requirements to claim exemption under Rule 506 of Regulation D.

3. Appointment of Placement Agent and Representations, Warranties and Agreements Thereof.

(a) On the basis of the representations, warranties and agreements herein contained, and subject to the terms and conditions herein set forth, the Company appoints you as its exclusive agent during the Offering Period to effect sales of the Securities for the account of the Company upon the other terms and conditions set forth herein and you agree to use your best efforts as such agent to produce Purchasers for the Securities during the Offering Period upon the terms and conditions set forth herein.

(b) You may in your discretion use the services of other registered brokers or dealers (“Participating Dealers”) in connection with the offering and sale of the Securities, and you may allow and pay to such Participating Dealers (but only as consideration for services rendered in placement of the Securities), out of the compensation payable to you by the Company on account of the sale of the Securities, an amount as determined by you in your discretion, provided that all such

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Participating Dealers are members in good standing of the National Association of Securities Dealers, Inc. (“NASD”) who are actually engaged in the investment banking or securities business and who have executed and delivered to you the written agreement prescribed by Section 24(c) of Article III of the NASD’s Rules of Fair Practice.

(c) As compensation for your services hereunder, the Company will (i) pay to you as Agent, a selling commission equal to 10% of the gross proceeds from the sales of the Notes and Warrants sold in this bridge financing; (ii) sell to the Agent, for an aggregate price of $100, ten-year warrants to purchase Common Stock at 120% of the exercise price of the warrants sold in this bridge financing, a number of shares of Common Stock equal to 10% of the number of shares of Common Stock that may be purchased pursuant to warrants sold in this bridge financing; (iii) pay the Agent a non-accountable expense allowance equal to 3% of the gross proceeds from sales of Notes and Warrants in this bridge financing; and (iv) reimburse the Agent for its accountable expenses of this bridge financing not to exceed $50,000. Such amounts shall be paid to you at the time of the final Closing Date of this offering. No compensation shall be payable under this Agreement with respect to the exercise of any of the Placement Agent’s Warrants.

(d) Your appointment by the Company as exclusive agent shall commence upon the date of the execution of this Agreement, and shall continue until and through the last day of the Offering Period, unless (i) the Securities shall be completely sold prior to that date, (ii) the offering has been terminated by agreement between you and us, or (iii) this Agreement shall be terminated at a prior date as provided herein.

(e) It is expressly understood and agreed that you are an independent contractor and that neither you nor your agent or employees are in any manner employees of the Company and that the Company shall have no responsibility for unemployment insurance, social security or income tax withholding in connection with your employees.

(f) You represent that you are a member in good standing of the NASD and a broker-dealer registered as such under the Securities Exchange Act of 1934, as amended (“1934 Act”), and under the securities laws of the states in which the Securities will be offered or sold by you and in which states registration as a broker-dealer is required and/or necessary.

(g) You will offer the Securities in accordance with the applicable provisions of the 1933 Act in a manner so as to preserve the exemption from registration as provided in Rule 506 and Regulation D under the 1933 Act and will not take, or omit to take, any action in connection with offers and sales of the Securities which would cause the offering not to be made in compliance therewith; you will not offer the Securities for sale in any jurisdiction unless and until the Company or your counsel shall have advised you that the Securities are exempt from registration under the state securities laws applicable thereto; and you have not and will not take any action which would require registration of the Securities under any federal or state securities laws, or any other laws, orders, rules or regulations without the consent of the Company.

(h) The offering of the Securities will be limited to persons who have executed a Purchase Agreement and who have otherwise satisfied you as to such person’s status as an “accredited investor” as defined in Rule 501(a) promulgated under the 1933 Act.

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(i) You shall make no representations concerning the offering or the Securities, except as set forth in the Purchase Agreement, and except for such supplemental information relating to the Company as shall be made available by the Company to offerees and their representatives as contemplated by Regulation D.