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                                                                     Exhibit 4.2
                         CERTIFICATE OF DESIGNATIONS OF
                      SERIES F CONVERTIBLE PREFERRED STOCK
                                       OF
                            DIAMETRICS MEDICAL, INC.
                             a Minnesota corporation

     The undersigned, being the duly elected and acting Chief Executive Officer
of Diametrics Medical, Inc., a Minnesota corporation (the "Corporation"), hereby
certifies that pursuant to the authority contained in Article 3 of the
Corporation's Amended and Restated Articles of Incorporation, as amended, and in
accordance with the provisions of Minnesota Statutes, Section 302A.401, Subd.
3(b), the Corporation's Board of Directors has adopted the following resolutions
creating a series of its Preferred Stock designated as Series F Convertible
Preferred Stock:

     WHEREAS, the Corporation's Amended and Restated Articles of Incorporation
provides for a class of shares known as Preferred Stock, issuable from time to
time in one or more series; and

     WHEREAS, the Board of Directors of the Corporation is authorized to
determine or alter the rights, preferences, privileges and restrictions granted
to or imposed upon any wholly unissued shares of Preferred Stock, to fix the
number of shares constituting any such series, and to determine the designation
thereof, or any of any of them.

     NOW, THEREFORE, BE IT RESOLVED, that the Board of Directors hereby fixes
and determines the designations of, the number of shares constituting, and the
rights, preferences, privileges and restrictions relating to, a new series of
Preferred Stock as follows:

     (a)  Designation. The series of Preferred Stock is hereby designated Series
F Convertible Preferred Stock (the "Series F Preferred Stock").

     (b)  Authorized Shares. The number of authorized shares constituting the
Series F Preferred Stock shall be 30,000 shares of such series.

     (c)  Dividends. Subject to the prior rights of holders of all classes of
stock at the time outstanding having prior rights as to dividends, the holder of
the Series F Preferred Stock shall be entitled to receive, when, as and if
declared by the Board of Directors, out of any assets of the Corporation legally
available therefor, such dividends as may be declared from time to time by the
Board of Directors.

     (d)  Liquidation Preference.

          (i)    Preference upon Liquidation, Dissolution or Winding Up. In the
event of any dissolution or winding up of the Corporation, whether voluntary or
involuntary, holders of each outstanding share of Series F Preferred Stock shall
be entitled to be paid first out of the assets of the Corporation available for
distribution to shareholders, whether such assets are capital, surplus or
earnings, an amount equal to $100 (the "Series F Purchase Price") per share of
Series F Preferred Stock held (as adjusted for any stock splits, stock dividends
or

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recapitalizations of the Series F Preferred Stock) and any declared but unpaid
dividends on such share, before any payment shall be made to the holders of the
Common Stock, or any other stock of the Corporation ranking junior to the Series
F Preferred Stock with regard to any distribution of assets upon liquidation,
dissolution or winding up of the Corporation. The holders of the Series F
Preferred Stock shall be entitled to share ratably, in accordance with the
respective preferential amounts payable on such stock, in any distribution which
is not sufficient to pay in full the aggregate of the amounts payable thereon.
If, upon any liquidation, dissolution or winding up of the Corporation, the
assets to be distributed to the holders of the Series F Preferred Stock shall be
insufficient to permit payment to such shareholders of the full preferential
amounts aforesaid, then all of the assets of the Corporation available for
distribution to shareholders shall be distributed to the holders of Series F
Preferred Stock. Each holder of the Series F Preferred Stock shall be entitled
to receive that portion of the assets available for distribution as the number
of outstanding shares of Series F Preferred Stock held by such holder bears to
the total number of shares of Series F Preferred Stock. Such payment shall
constitute payment in full to the holders of the Series F Preferred Stock upon
the liquidation, dissolution or winding up of the Corporation. After such
payment shall have been made in full, or funds necessary for such payment shall
have been set aside by the Corporation in trust for the account of the holders
of Series F Preferred Stock, so as to be available for such payment, such
holders of Series F Preferred Stock shall be entitled to no further
participation in the distribution of the assets of the Corporation.

          (ii)   Consolidation, Merger and Other Corporate Events. A
consolidation or merger of the Corporation (except into or with a subsidiary
corporation) or a sale, lease, mortgage, pledge, exchange, transfer or other
disposition of all or substantially all of the assets of the Corporation or any
reclassification of the stock of the Corporation (other than a change in par
value or from no par to par, or from par to no par or as the result of an event
described in subsections (iv) through (vii) of paragraph (f)), shall be regarded
as a liquidation, dissolution or winding up of the affairs of the Corporation
within the meaning of this paragraph (d). In no event shall the issuance of new
classes of stock, whether senior, junior or on a parity with the Series F
Preferred Stock, be deemed a "reclassification" under or otherwise limited by
the terms hereof.

          (iii)  Distribution of Cash and Other Assets. In the event of a
liquidation, dissolution or winding up of the Corporation resulting in the
availability of assets other than cash for distribution to the holders of the
Series F Preferred Stock, the holders of the Series F Preferred Stock shall be
entitled to a distribution of cash and/or assets equal to the value of the
liquidation preference stated in subsection (i) of this paragraph (d), which
valuation shall be made solely by the Board of Directors, and provided that such
Board of Directors was acting in good faith, shall be conclusive.

          (iv)   Distribution to Junior Security Holders. After the payment or
distribution to the holders of the Series F Preferred Stock of the full
preferential amounts aforesaid, the holders of the Common Stock then
outstanding, or any other stock of the Corporation ranking as to assets upon
liquidation, dissolution or winding up of the Corporation junior to the Series F
Preferred Stock, shall be entitled to receive ratably all of the remaining
assets of the Corporation.

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          (v)    Preference; Priority. References to a stock that is "senior"
to, on a "parity" with or "junior" to other stock as to liquidation shall refer,
respectively, to rights of priority of one series or class of stock over another
in the distribution of assets on any liquidation, dissolution or winding up of
the Corporation. The Series F Preferred Stock shall be senior to the Common
Stock of the Corporation and senior to any subsequent series of Preferred Stock
issued by the Corporation.

     (e)  Voting Rights. Except as otherwise required by law, the holder of
shares of Series F Preferred Stock shall not have the right to vote on matters
that come before the shareholders.

     (f)  Conversion Rights. The holders of Series F Preferred Stock will have
the following conversion rights:

          (i)    Right to Convert. Subject to and in compliance with the
provisions of this paragraph (g), any issued and outstanding shares of Series F
Preferred Stock may, at the option of the holder, be converted at any time or
from time to time into fully paid and nonassessable shares of Common Stock at
the conversion rate in effect at the time of conversion, determined as provided
herein; provided, that a holder of Series F Preferred Stock may at any given
time convert only up to that number of shares of Series F Preferred Stock so
that, upon conversion, the aggregate beneficial ownership of the Corporation's
Common Stock (calculated pursuant to Rule 13d-3 of the Securities Exchange Act
of 1934, as amended) of such holder and all persons affiliated with such holder
is not more than 9.99% of the Corporation's Common Stock then outstanding.

          (ii)   Mechanics of Conversion. Before any holder of Series F
Preferred Stock shall be entitled to convert the same into shares of Common
Stock, he shall surrender the certificate or certificates therefor, duly
endorsed, at the office of the Corporation or of any transfer agent for the
Common Stock, and shall give written notice to the Corporation at such office
that he elects to convert the same and shall state therein the number of shares
of Series F Preferred Stock being converted. Thereupon, the Corporation shall
promptly issue and deliver at such office to such holder of Series F Preferred
Stock a certificate or certificates for the number of shares of Common Stock to
which he shall be entitled. Such conversion shall be deemed to have been made
immediately prior to the close of business on the date of such surrender of the
shares of Series F Preferred Stock to be converted, and the person or persons
entitled to receive the shares of Common Stock issuable upon such conversion
shall be treated for all purposes as the record holder or holders of such shares
of Common Stock on such date.

          (iii)  Conversion Price. The number of shares into which one share of
Series F Preferred Stock shall be convertible shall be determined by dividing
$100 (the "Series F Purchase Price") by the then existing Conversion Price (as
set forth below), which shall be subject to adjustment from time to time in
certain instances, as provided below in this paragraph (g)(iii) (the "Conversion
Ratio"). The "Conversion Price" per share for the Series F Preferred Stock shall
be equal to 75% of the Market Price (as defined below and subject to adjustment
as described below), rounded to the nearest penny; provided, however, that in no
event shall the Conversion Price be less than $0.20 per share (subject to
adjustment as provided below) (the "Floor Price") or exceed the lower of (x)
$0.25 per share or (y) the average of the last 20 closing

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prices of the Common Stock on the trading days immediately preceding the
Original Issue Date, as defined below (the "Ceiling Price"). Both the Floor
Price and Ceiling Price shall be further adjusted upon the occurrence of any
event in paragraph (f)(iv)-(x).

     For purposes of determining the Conversion Price, the "Market Price" shall
equal the volume weighted average trading price of the lowest 3 inter-day
trading prices of the Common Stock, as obtained from Bloomberg Financial
Services or another similar service, for the five consecutive trading days
immediately preceding the conversion date (which may include trading days prior
to the date the Series F Preferred Stock is first issued (the "Original Issue
Date")).

     For purposes of illustration only, if the Market Price is $0.27 and the
Ceiling Price is in excess of $0.2025 at time of conversion, the Conversion
Ratio will be $100/$0.2025 = 493.83 to 1, allowing the 30,000 shares of Series F
Preferred Stock to be converted into 14,814,900 shares of Common Stock. On the
other hand, if the Market Price is $1.00 and the Ceiling Price is in excess of
$0.25 at time of conversion, the Conversion Ratio will be $100/$0.25 = 400 to 1,
allowing the 30,000 shares of Preferred Stock to be converted into 12,000,000
shares of Common Stock. Similarly, if the Market Price is $0.05 at time of
conversion, the Conversion Ratio will be $100/$0.20 = 500 to 1, allowing the
30,000 shares of Preferred Stock to be converted into 15,000,000 shares of
Common Stock, the maximum number of shares of Common Stock into which the Series
F Preferred Stock may be converted.

          (iv)   Adjustment for Stock Splits and Combinations. If the
Corporation shall at any time, or from time to time after the Original Issuance
Date, effect a subdivision of the outstanding Common Stock, the Conversion Price
in effect immediately prior thereto shall be proportionately decreased, and
conversely, if the Corporation shall at any time or from time to time after the
Original Issuance Date combine the outstanding shares of Common Stock, the
Conversion Price then in effect immediately before the combination shall be
proportionately increased. Any adjustment under this paragraph (f)(iv) shall
become effective at the close of business on the date the subdivision or
combination becomes effective.

          (v)    Adjustment for Certain Dividends and Distributions. In the
event the Corporation at any time, or from time to time after the Original
Issuance Date, shall make or issue, or fix a record date for the determination
of holders of Common Stock entitled to receive, a dividend or other distribution
payable in additional shares of Common Stock, then and in each such event the
Conversion Price for the Series F Preferred Stock then in effect shall be
decreased as of the time of such issuance or, in the event such a record date
shall have been fixed, as of the close of business on such record date, by
multiplying the Conversion Price for such Series F Preferred Stock then in
effect by a fraction:

                      (A)  the numerator of which shall be the total number of
     shares of Common Stock issued and outstanding immediately prior to the time
     of such issuance or the close of business on such record date, and

                      (B)  the denominator of which shall be the total number of
     shares of Common Stock issued and outstanding immediately prior to the time
     of such issuance or the close of business on such record date plus the
     number of shares of Common Stock issuable in payment of such dividend or
     distribution;

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provided, however, if such record date shall have been fixed and such dividend
is not fully paid or if such distribution is not fully made on the date fixed
therefor, the Conversion Price for the Series F Preferred Stock shall be
recomputed accordingly as of the close of business on such record date and
thereafter, the Conversion Price for the Series F Preferred Stock shall be
adjusted pursuant to this paragraph (f)(v) as of the time of actual payment of
such dividends or distributions.

          (vi)   Adjustments for Other Dividends and Distributions. In the event
the Corporation at any time or from time to time after the Original Issuance
Date shall make or issue, or fix a record date for the determination of holders
of Common Stock entitled to receive, a dividend or other distribution payable in
securities of the Corporation other than shares of Common Stock, then and in
each such event provision shall be made so that the holders of such Series F
Preferred Stock shall receive upon conversion thereof in addition to the number
of shares of Common Stock receivable thereupon, the amount of securities of the
Corporation that they would have received had their Series F Preferred Stock
been converted into Common Stock on the date of such event and had thereafter,
during the period from the date of such event to and including the conversion
date, retained such securities receivable by them as aforesaid during such
period giving application to all adjustments called for during such period under
this paragraph (f) with respect to the rights of the holders of the Series F
Preferred Stock.

          (vii)  Adjustment for Reclassification Exchange or Substitution. If
the Common Stock issuable upon the conversion of the Series F Preferred Stock
shall be changed into the same or a different number of shares of any class or
classes of stock, whether by capital reorganization, reclassification or
otherwise (other than a subdivision or combination of shares or stock dividend
provided for above, or a reorganization, merger, consolidation or sale of assets
provided for elsewhere in this paragraph (f)), then and in each such event the
holder of each share of Series F Preferred Stock shall have the right thereafter
to convert such share into the kind and amount of shares of stock and other
securities and property receivable upon such reorganization, reclassification or
other change, by holders of the number of shares of Common Stock into which such
shares of Series F Preferred Stock might have been converted immediately prior
to such reorganization, reclassification, or change, all subject to further
adjustment as provided herein.

          (viii) Adjustment for Event of Default. Upon (A) commencement by the
Corporation of a voluntary case or proceeding under the bankruptcy laws, (B) the
Corporation's failure to discharge or stay a bankruptcy proceeding within 60
days of such action being taken against the Corporation, (C) the Corporation's
failure to file the First Registration Statement with the SEC within 30 days of
the Closing Date, other than due to a delay not caused by the Corporation or (D)
the de-listing of the Corporation's Common Stock from the OTC Bulletin Board (as
such terms are defined in that certain Subscription Agreement dated January 14,
2004 by and among the Corporation and the purchasers named therein), the
Conversion Price shall be adjusted to 65% of the Market Price, rounded to the
nearest penny.

          (ix)   Adjustment of Floor Price. If the Corporation's cash flow is at
least 20% lower than the six month forward cash flow plan provided to the
purchasers of the Series F Preferred Stock on the Closing Date, the Floor Price
will be decreased from $0.20 to $0.15.

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          (x)    Reorganization, Mergers, Consolidations or Sales of Assets. If
at any time or from time to time there shall be a capital reorganization of the
Common Stock (other than a subdivision, combination, reclassification or
exchange of shares provided for elsewhere in this paragraph (f)) or a merger or
consolidation of the Corporation with or into another corporation, or the sale
of all or substantially all of the Corporation's properties and assets to any
other person, then, as a part of such reorganization, merger, consolidation or
sale, provision shall be made so that the holders of the Series F Preferred
Stock shall thereafter be entitled to receive upon conversion of such Series F
Preferred Stock, the number of shares of stock or other securities or property
of the Corporation or of the successor corporation resulting from such merger or
consolidation or sale, to which a holder of Common Stock deliverable upon
conversion would have been entitled on such capital reorganization, merger,
consolidation or sale. In any such case, appropriate adjustment shall be made in
the application of the provisions of this paragraph (f) with respect to the
rights of the holders of the Series F Preferred Stock after the reorganization,
merger, consolidation or sale to the end that the provisions of this paragraph
(f) (including adjustment of the Conversion Price then in effect and the number
of shares purchasable upon conversion of the Series F Preferred Stock) shall be
applicable after that event as nearly equivalent as may be practicable.

          (xi)   Certificate of Adjustment. In each case of an adjustment or
readjustment of the Conversion Price for the number of shares of Common Stock or
other securities issuable upon conversion of the Series F Preferred Stock, the
Corporation shall compute such adjustment or readjustment in accordance herewith
and the Corporation's Chief Financial Officer shall prepare and sign a
certificate showing such adjustment or readjustment, and shall mail such
certificate by first class mail, postage prepaid, to each registered holder of
the Series F Preferred Stock at the holder's address as shown in the
Corporation's books. The certificate shall set forth such adjustment or
readjustment, showing in detail the facts upon which such adjustment or
readjustment is based.

          (xii)  Notices of Record Date. In the event of (A) any taking by the
Corporation of a record of the holders of any class or series of securities for
the purpose of determining the holders thereof who are entitled to receive any
dividend or other distribution or (B) any reclassification or recapitalization
of the capital stock of the Corporation, any merger or consolidation of the
Corporation or any transfer of all or substantially all of the assets of the
Corporation to any other corporation, entity or person, or any voluntary or
involuntary dissolution, liquidation or winding up of the Corporation, the
Corporation shall mail to each holder of Series F Preferred Stock at least 10
days prior to the record date specified therein, a notice specifying (1) the
date on which any such record is to be taken for the purpose of such dividend or
distribution and a description of such dividend or distribution, (2) the date on
which any such reorganization, reclassification, transfer, consolidation,
merger, dissolution, liquidation or winding up is expected to become effective
and (3) the time, if any is to be fixed, as to when the holders of record of
Common Stock (or other securities) shall be entitled to exchange their shares,
of Common Stock (or other securities) for securities or other property
deliverable upon such reorganization, reclassification, transfer, consolidation,
merger, dissolution, liquidation or winding up.

          (xiii) Fractional Shares. No fractional shares of Common Stock shall
be issued upon conversion of the Series F Preferred Stock. In lieu of any
fractional shares to which the

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holder would otherwise be entitled, the Corporation shall pay cash equal to the
product of such fraction multiplied by the fair market value of one share of the
Corporation's Common Stock on the date of conversion, as determined in good
faith by the Board of Directors.

          (xiv)  Reservation of Stock Issuable Upon Conversion. The Corporation
shall at all times reserve and keep available out of its authorized but unissued
shares of Common Stock, solely for the purpose of effecting the conversion of
the shares of the Series F Preferred Stock, such number of its shares of Common
Stock as shall from time to time be sufficient to effect the conversion of all
outstanding shares of Series F Preferred Stock, and if at any time the number of
authorized but unissued shares of Common Stock shall not be sufficient to effect
the conversion of all then outstanding shares of Series F Preferred Stock, the
Corporation will take such corporate action as may, in the opinion of its
counsel, be necessary to increase its authorized but unissued shares of Common
Stock to such number of shares as shall be sufficient for such purpose.

          (xv)   Notices. Any notice required by the provisions of this
paragraph (f) to be given to the holders of shares of Series F Preferred Stock
shall be deemed given (A) if deposited in the United States mail, postage
prepaid, or (B) if given by any other reliable or generally accepted means
(including by facsimile or by a nationally recognized overnight courier
service), in each case addressed to each holder of record at his address (or
facsimile number) appearing on the books of the Corporation.

          (xvi)  Payment of Taxes. The Corporation will pay all transfer taxes
and other governmental charges that may be imposed in respect of the issue or
delivery of shares of Common Stock upon conversion of shares of Series F
Preferred Stock.

          (xvii) No Dilution or Impairment. The Corporation shall not amend its
Articles of Incorporation or participate in any reorganization, transfer of
assets, consolidation, merger, dissolution, issue or sale of securities or any
other voluntary action, for the purpose of avoiding or seeking to avoid the
observance or performance of any of the terms to be observed or performed
hereunder by the Corporation, without the approval of a majority of the then
outstanding Series F Preferred Stock.

     (g)  No Reissuance of Preferred Stock. Any shares of Series F Preferred
Stock acquired by the Corporation by reason of purchase, conversion or otherwise
shall be canceled, retired and eliminated from the shares of Series F Preferred
Stock that the Corporation shall be authorized to issue. All such shares shall
upon their cancellation become authorized but unissued shares of Preferred Stock
and may be reissued as part of a new series of Preferred Stock subject to the
conditions and restrictions on issuance set forth in the Articles of
Incorporation or in any certificate of designation creating a series of
Preferred Stock or any similar stock or as otherwise required by law.

     (h)  Severability. If any right, preference or limitation of the Series F
Preferred Stock set forth herein is invalid, unlawful or incapable of being
enforced by reason of any rule, law or public policy, all other rights,
preferences and limitations set forth herein that can be given effect without
the invalid, unlawful or unenforceable right, preference or limitation shall
nevertheless

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remain in full force and effect, and no right, preference or limitation herein
shall be deemed dependent upon any other such right, preference or limitation
unless so expressed herein.

     IN WITNESS WHEREOF, Diametrics Medical, Inc. has caused this Certificate of
Designations of Series F Preferred Stock to be executed by David B. Kaysen, its
Chief Executive Officer, this 14th day of January, 2004.

                                          /s/ David B. Kaysen
                                        ----------------------------------------
                                        David B. Kaysen, Chief Executive Officer

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