This Investment Agreement dated as of December 28, 2004  by and between**DIASYS CORPORATION**, a Delaware corporation with a principal  place of business at 81 West Main Street, Waterbury, Connecticut 06702 (the  "Company"), and **JOHN WINFIELD**, an individual residing at 800 Moraga Drive,  Los Angeles, California (the "Investor").  1.           Purchase of  Units. Subject to the terms and conditions contained in this Agreement,  the Investor agrees to purchase, and the Company agrees to sell, One Million  Two Hundred Fifty Thousand units (the "Units"), each consisting of: (i) one  share of the Common Stock, $.001 par value ("Common Stock") of the Company,  and (ii) one Common Stock Purchase Warrant (the "Warrant") entitling the holder  to purchase one share of Common Stock at Fifty Cents ($.50) per share at any  time prior to third anniversary of the date hereof, such Warrant to be in the  form of Exhibit A attached hereto.

2.           Purchase  Price. The Purchase Price for the Units shall be forty cents ($.40) per  Unit, for an aggregate purchase price of Five Hundred Thousand Dollars ($500,000).  The Purchase Price shall be paid by wire transfer of Federal funds on or before  2:00 P.M. Eastern Time on Thursday, December 30, 2004 to the account of the  Company as follows: 

|   | LaSalle Bank, N.A.       135 South LaSalle Street       Chicago, IL 60603       ABA # 071-000 505 |
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|   | DiaSys Corporation       Acct # 5800693011                                                        |

  3.           Unregistered  Securities. The Investor understands that Units, the Common Stock, the Warrants  and the shares of Common Stock issuable upon exercise of the Warrants (collectively,  the "Securities") are suitable only for sophisticated investors and are being  offered and sold under the exemption provided under Sections 4(2) and 4(6) of  the Securities Act of 1933, as amended (the "Securities Act"), and Rule 506  promulgated thereunder and similar state securities law exemptions for private  offerings. The Investor makes the following representations, declarations and  warranties with the intent that the same be relied upon in determining his suitability  as a shareholder in the Company: 

|   | (a) | The Investor is an accredited investor, as      that term is defined in Rule 501(a) under the Securities Act, in that he      is a natural person and either (i) his individual net worth and that of      his spouse on the date hereof exceeds $1,000,000 or (ii) he had an individual      income in excess of $200,000 in each of the two most recent years or joint      income with his spouse in excess of $300,000 in each of those years and      he has a reasonable expectation of reaching the same income level in the      current year. |
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|   | (b) | He understands: (i) that the Securities have      not been registered under the Securities Act, nor pursuant to the provisions      of the securities or other laws of any other applicable jurisdictions in      reliance on exemptions for private offerings contained in Section 4(2) and      4(6) of the Securities Act, Rule 506 promulgated thereunder and in the laws      of such jurisdictions; and (ii) that the Securities are to be issued in      reliance upon such exemptions based upon his representations, warranties      and agreements set forth herein. |
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|   | (c) | The Investor agrees that the Securities may      not be resold pledged or otherwise transferred unless they are registered      under such securities laws or unless exemptions from applicable registration      requirements are available and that the certificate evidencing his Securities      will bear a legend to such effect.                                                                                                                                                                                                                                        |

|   | COMPANY:       DIASYS CORPORATION                                                                                                                 |
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|   | By: S/ GREGORY WITCHEL            Gregory Witchel             Chief Executive Officer |
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|   | INVESTOR:                                                                                                                                         |
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|   | S/ JOHN WINFIELD      John Winfield                                                                                                               |

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