This Amendment No. 6 amends and supplements the Solicitation/Recommendation Statement on Schedule 14D-9 initially filed with the Securities and Exchange Commission (the “SEC”) on January 25, 2011, as amended by Amendment No. 1 filed on January 31, 2011, Amendment No. 2 filed on February 8, 2011, Amendment No. 3 filed on February 16, 2011, Amendment No. 4 filed on February 25, 2011, and Amendment No. 5 filed on March 4, 2011 (as previously filed with the SEC, and as the same may further be amended or supplemented from time to time, the “Schedule 14D-9”), by Microfluidics International Corporation, a Delaware corporation (“Microfluidics” or the “Company”), relating to the offer (the “Offer”) by Nano Merger Sub, Inc., a Delaware corporation (“Purchaser”) and a wholly-owned subsidiary of IDEX Corporation, a Delaware corporation (“IDEX”), as set forth in a Tender Offer Statement filed by IDEX and Purchaser on Schedule TO, dated January 25, 2011, as amended by Amendment No. 1 filed on January 28, 2011, Amendment No. 2 filed on February 16, 2011, Amendment No. 3 filed on February 25, 2011, Amendment No. 4 filed on March 4, 2011, and Amendment No. 5 filed on March 11, 2011 (as previously filed with the SEC, and as the same may further be amended or supplemented from time to time, the “Schedule TO”), to purchase all outstanding shares of common stock, par value $0.01 per share (the “Shares”) of Microfluidics, at a purchase price of $1.35 per Share, net to the selling stockholders in cash, without interest thereon and less any required withholding taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated January 25, 2011, and in the related Letter of Transmittal, copies of which are filed with the Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B), respectively. Any capitalized terms used and not otherwise defined herein shall have the meanings ascribed to such terms in the Schedule 14D-9.

Item 8 of the Schedule 14D-9 is hereby amended and supplemented by inserting the following new subsection (l) at the end thereof:

     At 5:00 p.m., New York City time, on Thursday, March 10, 2011, the subsequent offering period (as extended) expired. Registrar and Transfer Company, the depositary for the Offer, has advised the Company that, as of such time, a total of 7,509,382 Shares had been validly tendered and not properly withdrawn during the initial offering period and the subsequent offering period (as extended), representing approximately 71.99% of the Shares outstanding. Pursuant to the terms of the Offer, as of March 11, 2011, Purchaser has accepted for payment all Shares validly tendered and not validly withdrawn during the initial offering period and all Shares validly tendered during the subsequent offering period (as extended), and the consideration for all such Shares either has been paid or promptly will be paid. In addition, as of March 11, 2011, approximately 12,699 Shares have been acquired by Purchaser through open market purchases at $1.35 per Share, which Shares when combined with the 7,509,382 Shares validly tendered and not properly withdrawn during the initial offering period and the subsequent offering period, represent approximately 72.12% of the Shares outstanding.

     In accordance with the Merger Agreement, Purchaser has informed the Company that it intends to exercise its Top-Up Option. The exercise of the Top-Up Option will allow Purchaser to increase its share ownership percentage of the Company through the purchase of newly issued shares of the Company’s common stock directly from the Company for an immediate cash payment equal to the aggregate par value of the Shares issued upon the exercise of the Top-Up Option and delivery of a secured promissory note for the remainder of the exercise price for the Top-Up Option. The promissory note will bear interest at 9% per annum and will be due one year from the date of the purchase of Shares pursuant to the Top-Up Option. Pursuant to the exercise of the Top-Up Option, Purchaser will purchase directly from the Company a total of 18,656,013 newly issued shares of the Company’s common stock. As a result, Purchaser will own more than 90% of the outstanding shares of the Company’s common stock, when combined with the Shares purchased in the Offer (including Shares purchased in the subsequent offering period (as extended)) and on the open market.

     Following the exercise of the Top-Up Option, in accordance with the Merger Agreement, Purchaser intends to effect a short-form merger under Section 253 of the DGCL of Purchaser with and into the Company, with the Company surviving and continuing as a wholly-owned subsidiary of IDEX. As a result of the Merger, each Share that is issued and outstanding and that was not accepted for payment pursuant to the Offer (other than (i) Shares that are held by any stockholder who demands and perfects appraisal rights under the DGCL, and (ii) Shares held by IDEX or any subsidiary of IDEX, including Purchaser, and any Shares held by the Company as treasury shares or held by Microfluidics Corporation, the Company’s wholly-owned subsidiary, which Shares will be cancelled without any conversion) will be

cancelled and converted into the right to receive $1.35 per Share, net to the stockholder in cash, without interest thereon and less any required withholding taxes (the “Merger Consideration”). As a result of the Merger, the Shares will no longer be eligible for quotation on the Over-the-Counter Bulletin Board or listed on any other market or securities exchange. Information regarding the Merger will be mailed to the Company’s stockholders who did not tender their Shares in the Offer and instructions will be mailed to stockholders outlining the steps to be taken to obtain the Merger Consideration.

     On March 11, 2011, IDEX issued a press release announcing the expiration of the subsequent offering period (as extended), a copy of which is filed as Exhibit (a)(1)(R) hereto and is incorporated herein by reference.”

Item 9 of the Schedule 14D-9 is hereby supplemented by adding the following exhibit:

     After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.