**SENIOR
      SECURED PROMISSORY NOTE**




$
      150,000.00 March 28, 2008


Sarasota,
      Florida




FOR
      VALUE
      RECEIVED, the undersigned, **INVISA, INC.**, a Nevada corporation
      (“**Borrower**”) having an address at 290 Cocoanut Avenue,
      Sarasota, Florida, 34236 promises to pay to the order of Centurian Investors,
      Inc, a Delaware corporation (“**Lender**”), having an office
      at 290  Cocoanut Avenue, Sarasota, Florida 34236, or such other place
      as the Lender may designate inwriting, the principal amount up to and not to
      exceed ONE HUNDRED FIFTY THOUSAND United States Dollars (U.S. $150,000.00),
      to
      the extent advanced hereunder and then outstanding, with interest on the unpaid
      principal balance from the date of this Senior Secured Promissory Note (this
      “**Promissory Note**”), until paid, at the Interest Rate (as
      hereinafter defined) provided herein.




1.           **Rate
      of Interest**.  The outstanding principal balance of this
      Promissory Note shall bear interest at ten percent (10%) per annum (the
“**Interest Rate**”).




2.           **Date
      and Time of Payment**.  The outstanding principal balance
      of this Promissory Note, together with all accrued and unpaid
      interest,  shall be paid in full on earlier to occur of (a) the
      Maturity Date or (b) the date of termination of this Promissory Note, whether
      by
      its terms, by prepayment, or by acceleration.  All amounts outstanding
      hereunder shall constitute Borrower’s obligations hereunder, and such
      obligations include without limitation all principal, interest (including all
      interest which accrues after the commencement of any case or proceeding by
      or
      against Borrower in bankruptcy whether or not allowed in such case or
      proceeding), expenses, attorneys’ fees and any other sum chargeable to Borrower
      hereunder and owing to Lender under this Promissory Note (all such obligations
      and all other obligations of Borrower under this Promissory Note ,(the
“**Obligations**”).  No principal amount of this
      Note paid or prepaid may be reborrowed.




3.           **Default
      Rate**.  Notwithstanding Section 1, after the
      occurrence of any Event of Default and for so long as such Event of Default
      continues, and in any event from and after the Maturity Date, all principal,
      interest and other amounts payable under this Promissory Note shall bear
      interest until paid in full at a rate of interest equal to four percent (4%)
      above the per annum rate otherwise applicable hereunder (the “**Default
      Rate**”).




4.           **Computation
      of Interest**.  Interest on the principal amount hereof and
      all other Obligations shall be computed on the basis of a 360-day year, and
      shall be charged for the actual number of days elapsed during any month or
      other
      accrual period.




5.           **Manner
      of Payment**.  All payments by Borrower in respect of any
      Obligations shall be made without deduction, defense, set off or counterclaim,
      free and clear of all taxes delivered to Lender.




6.           **Maturity**.  To
      the extent not sooner due and payable in accordance with this Promissory Note,
      the Obigations  shall be due and payable on December 31, 2007 (the
“**Maturity Date**”).




7.           **Application
      of Payments**.  All payments shall be applied to amounts
      then due and payable in the following order:  (a) to Lender’s costs
      and expenses reimbursable in connection herewith; (b) to interest accrued on
      the
      outstanding principal balance of this Promissory Note; (c) to the principal
      amount hereof; and (d) to all other Obligations, or in such other manner as
      Lender shall determine in its sole and exclusive discretion.




8.           **Procedure
      for Borrowing and Use of Proceeds****.**The proceeds of
      this Promissory Note shall be funded in multiple advances (each, an
“**Advance**”) by Lender to Borrower in the amounts and on
      such dates as determined by Lender based on requests from
      Borrower.  Borrower shall give Lender notice requesting that Lender
      make an Advance in accordance herewith specifying (a) the Borrowing Date, (b)
      the amount requested and (c) a detailed, itemized list of the use of such
      Advance.  Upon receipt of such notice from Borrower, Lender shall
      determine, in its sole and exclusive discretion, whether it shall make such
      amount available to Borrower on the Borrowing Date.  Upon each
      Advance, Lender shall record each Advance on Schedule I to this Promissory
      Note.  For purposes of this Section 8, the Borrowing Date shall mean
      any business day specified in the notice pursuant to this Section 8 as a date
      on
      which Borrower requests Lender to make a loan
      hereunder.    The obligation of Lender to make each
      subsequent Advance following the initial Advance hereunder is subject to the
      Lenders approval of the loan request made by Borrower in accordance with this
      Section 8 and shall be funded in the sole and exclusive discretion of
      Lender.  As of the date hereof, Borrower has received an aggregate
      Advance of Thirty Thousand Three Hundred ($30,300.00) Dollars  under
      this Note.




9.           **Security****.**  This
      Promissory Note shall be secured by (i) Twenty Million (20,000,000) shares
      of
      common stock of Borrower to be issued as of the date hereof and held in escrow
      and a continuing first priority security interest in all of Borrower’s right,
      title, and interest in and to, all property of Borrower (collectively, the
      “**Collateral**”), as more specifically set forth in the
      Security Agreement executed by Borrower in favor of Lender dated as of February
      28, 2007.  (the “Security Agreement”).




10.           **Priority******This
      Promissory Note shall be a senior obligation of Borrower, and for so long as
      this Promissory Note shall be outstanding, (i) Borrower shall be prohibited
      from
      incurring any and all future indebtedness without the prior written consent
      of
      Lender and (ii) any and all future indebtedness approved by Borrower in writing
      shall be deemed subordinate and inferior to, all respective right, title and
      interest of Lender, in, to and under this Promissory Note, this Security
      Agreement and any and all documents and instruments evidencing, securing or
      otherwise relating to this Promissory Note.




11.           **Representations
      and Warranties****.**Borrower makes the
      following representations and warranties to Lender, which representations and
      warranties shall be true, correct, and complete as of the date hereof and shall
      survive the execution and delivery of this Promissory Note.




(a)  **Due
      Organization and Qualification**.  Borrower is duly
      organized and validly existing and in good standing under the laws of the
      jurisdiction of its organization and qualified to do business in any
      jurisdiction where it is required to be so qualified, and has all requisite
      power and authority to (i) own its assets and carry on its business, and (ii)
      execute, deliver and perform its Obligations.


(b)  **Due
      Authorization; No Conflict**.  The execution, delivery, and
      performance by Borrower of this Promissory Note has been duly authorized by
      all
      necessary action on the part of Borrower.  This Promissory Note has
      been duly executed and delivered by Borrower.  The execution,
      delivery, and performance by Borrower of this Promissory Note and the
      consummation of the transactions contemplated hereby, do not and will not (i)
      violate in any material respect any provision of federal, state, provincial
      or
      local law or regulation applicable to Borrower, its organizational documents,
      or
      any order, judgment, or decree of any court or other governmental authority,
      (ii) conflict with, result in a breach or termination of, or constitute (with
      due notice or lapse of time or both) a default under any material contractual
      obligation of Borrower, (iii) result in or require the creation or imposition
      of
      any lien of any nature whatsoever upon any properties or assets of Borrower,
      other than liens or security interests in favor of Lender, or (iv) require
      any
      approval of any of Borrower’s stockholders or any approval or consent of any
      other person or entity, other than consents or approvals that have been obtained
      and that are still in force and effect.  The execution, delivery, and
      performance by Borrower of this Promissory Note do not and will not require
      any
      registration with, consent, or approval of, or notice to, or other action with
      or by, any governmental authority, other than consents or approvals that have
      been obtained and that are still in force and effect.  This Promissory
      Note when executed and delivered by Borrower will be the legally valid and
      binding obligation of Borrower, enforceable against Borrower in accordance
      with
      its term, except as enforcement may be limited by equitable principles or by
      bankruptcy, insolvency, reorganization, moratorium, or similar laws relating
      to
      or limiting creditors’ rights generally.


(c)  **No
      Litigation**.  No litigation, investigation or proceeding of or
      before any arbitrator or government authority is (i) pending or, to the
      knowledge of Borrower, threatened with respect to this Promissory Note or the
      Collateral or any of the transactions contemplated hereby or (ii) pending or,
      to
      the knowledge of Borrower, threatened by or against Borrower, its properties
      or
      revenues which, if adversely determined, would have a material adverse effect
      on
      its business, operations, property or financial condition, when taken as a
      whole.


(d)  **No
      Default**.  Borrower is not in default under or with
      respect to any contractual obligation and no event of default has occurred
      or is
      continuing with respect to Borrower.


(e)  **Taxes****.**  Borrower
      has filed or caused to be filed all tax returns required to be filed by it
      and
      has paid all taxes due and payable on said returns or on any assessments made
      against Borrower or any of its property.   All other taxes, fees
      or other charges on Borrower or any of its property by any governmental
      authority have been paid and no tax liens have been filed.


12.  **Covenants
      of
      Borrower.**As of the date hereof and so long as the
      Obligations hereunder shall be outstanding:




(a)  Borrower
      will preserve
      and keep in force and effect, its corporate existence and all licenses and
      permits necessary to the proper conduct of its business;





(b)  Borrower
      will promptly
      pay and discharge, all lawful taxes, assessments, charges or levies imposed
      upon
      Borrower, or upon or in respect of all or any part of the property or business
      of Borrower, all trade accounts payable in accordance with usual and customary
      business terms and all claims for work, labor or materials, which if unpaid
      might become a lien or charge upon any property of Borrower; provided,
      Borrower shall not be required to pay such tax, assessment, charge, levy,
      account payable or claim if (i) the validity, applicability or amount thereof
      is
      being contested in good faith by appropriate action or proceeding which will
      prevent the forfeiture or sale of any property of Borrower, and (ii) Borrower
      shall set aside on its books, reserves deemed by it to be adequate with respect
      thereto;





(c)  Borrower
      will promptly
      comply with all laws, ordinances or governmental rules and regulation to which
      it is subject, the violations of which would materially or adversely affect
      its
      properties, business, prospects, profits or condition or would result in any
      material lien or charge upon any property of Borrower;





(d)  Borrower
      will maintain,
      preserve and keep its properties which are used or useful in the conduct of
      its
      business in good repair and working order;





(e)  Borrower
      will not
      create, assume or incur or in any manner become liable with respect of any
      indebtedness except this Promissory Note and any indebtedness of Borrower
      incurred prior to the date hereof.





(f)  Borrower
      will not create
      or incur any mortgage, pledge, security interest, encumbrance, lien or charge
      of
      any kind (a “Lien”) on its or its property or assets, whether now owned or
      hereinafter acquired, or upon any income or profits
      therefrom  except





(i)           Liens
      for property taxes and assessments or levies and liens that are not yet due
      and
      payable;





(ii)           Liens
      of or resulting from any judgment or award, the time for appeal or petition
      for
      rehearing of which shall not have expired or in respect of which the Company
      shall in good faith be prosecuting an appeal or proceeding for a review and
      in
      respect of which a stay of execution pending such appeal or proceeding for
      review shall have been secured; or





(iii)           Liens
      or priority claims (A) incidental to the conduct of business, (B) created by
      any
      material agreement of Borrower entered into prior to and currently in effect
      as
      of the date hereof or (C) the ownership or lease of properties and assets and
      not in connection with the borrowing of money, provided, in each case,
      the obligation secured is not overdue, or if overdue, is being contested in
      good
      faith by appropriate actions or proceedings and provided, furtherthat Borrower shall have received the prior written consent
      of Lender to any
      Lien described in (A) or (C) above; or





13.           **Events
      of Default; Remedies; Acceleration**.  (a) The occurrence
      of any one or more of the following events (regardless of the reason therefor)
      shall constitute an “**Event of Default**”
hereunder:




(i)
      Borrower fails to make any payment of outstanding principal balance of this
      Promissory Note , or interest thereon, or any of the other Obligation when
      due
      and payable;




(ii)
      Any representation or warranty of Borrower made in this Promissory Note, the
      Security Agreeent,  or any other document made by or on behalf of
      Borrower in connection herewith and the transactions contemplated hereby proves
      to have been false or incorrect in any material respect or Borrower shall fail
      to comply in all respects with any covenant herein or therein;




(iii)
      Borrower shall violate any
      provision of this Promissory Note, the Security Agreement or any other document
      made by or on behalf of Borrower in connection herewith and the transactions
      contemplated hereby, including, without limitiation, failure to comply with
      the
      terms and provisions of Section 8 of this Promissory Note;




(iv)
      A case or proceeding is commenced against Borrower seeking a decree or order
      (i)
      under Title 11 of the United States Bankruptcy Code (11 U.S.C. §§101 *et
      seq.*, as amended, and any successor statute, the “**Bankruptcy
      Code**”), or any other applicable federal, state or foreign
      bankruptcy or other similar law, rule or regulation, (ii) appointing a
      custodian, receiver, liquidator, assignee, trustee or sequestrator (or similar
      official) for Borrower or for any substantial part of Borrower’s assets, or
      (iii) ordering the winding-up or liquidation of the affairs of s Borrower,
      and
      such case or proceeding shall remain undismissed or unstayed for sixty (60)
      days
      or more or a decree or order granting the relief sought in such case or
      proceeding shall be entered by a court of competent jurisdiction;




(v)
      Borrower, without the prior written consent of Lender (A) files a petition
      seeking relief under the Bankruptcy Code, or any other applicable federal,
      state
      or foreign bankruptcy or other similar law, rule or regulation, (B) consents
      to
      or fails to contest in a timely and appropriate manner the institution of
      proceedings thereunder or the filing of any such petition or the appointment
      of
      or taking possession by a custodian, receiver, liquidator, assignee, trustee
      or
      sequestrator (or similar official) for Borrower or for any substantial part
      of
      Borrower’s assets, (C) makes an assignment for the benefit of creditors, (D)
      takes any action in furtherance of any of the foregoing; or (E) admits in
      writing its inability to, or is generally unable to, pay its debts as such
      debts
      become due;




(vi)  If
      this Promissory Note, the Security Agreement, or any financing statement,
      document or other instrument executed, delivered or filed in connection herewith
      or with the security interest granted to Lender hereunder, shall, for any
      reason, fail or cease to create a valid and perfected lien on or security
      interest in any or all of the Collateral or the Collateral shall be compromised,
      encumbered or, in the case of the common stock, invalid, cancelled or otherwise
      rescinded;




(vi)
      If
      Borrower shall default on any material obligations of Borrower or an event
      of
      default shall occur with respect to any material agreement of Borrower, whether
      such agreement shall be in effect or effective subsequent to this Promissory
      Note.




(b)  Immediately
      upon the
      occurrence of any Event of Default, all of the Obligations of Borrower
      hereunder shall become immediately due and payable to Lender and the Obligations
      shall thereafter accrue interest at the Default Rate from the date of any Event
      of Default until such Obligations are paid in full (an
“Accelleration”).  Promptly upon the occurrence of an Acceleration,
      Lender shall send Borrower written notice of the date upon which the
      Acceleration is effective and the names of  two (2) representatives of
      Lender (“Lender Nominees”) to be immediately appointed to the Board of Directors
      of Borrower (the “Default Notice”).  The Lender Nominees shall be
      appointed to the Board of Directors of Borrower not less than five days
      following the date of the Default Notice.  Except with respect to an
      Event of Default  under Section 13(a)(iv) and (v), Borrower shall have
      forty five (45) days (the forty fifth day hereinafter being the “Final Payment
      Date”) from the date of the Default Notice to pay Lender the total amount of the
      Obligations due and owning under this Promissory Note.  In the event
      that Borrower shall fail to satisfy in full all of the outstanding Obligations
      under this Promissory Note on or before the Final Payment Date, then Lender
      may
      (i) proceed to protect and enforce Lender’s rights by suit in equity, action at
      law and/or other appropriate proceeding, either for specific performance of
      any
      covenant or condition contained in this Promissory Note, the Security Agreement,
      or in any instrument or document delivered to Lender pursuant to this Promissory
      Note , or in aid of the exercise of any power granted in this Promissory Note
      or
      any such instrument or document, and (ii) proceed to enforce payment of the
      Obligations in such manner as Lender may elect, including the foreclosure of
      the
      Collateral in accordance with the terms of the Security Agreement, and to
      realize upon any and all rights of Lender hereunder.  Upon the
      occurrence of any Event of Default under Section 13(a)(iv) and (v), Lender
      shall
      have a right to immediately enforce its rights hereunder and proceed against
      or
      foreclose upon the Collateral without regard to the 45 day period set forth
      in
      this Section 13(b) To the extent not prohibited by applicable law which cannot
      be waived, all of Lender’s rights hereunder shall be
      cumulative.  Lender shall have all other rights and remedies not
      inconsistent herewith as provided under applicable law or in equity, and no
      exercise by Lender of one right or remedy shall be deemed an election, and
      no
      waiver by Lender of any Event of Default shall be deemed a continuing
      waiver.   No delay by Lender shall constitute a waiver, election
      or acquiescence by it.




(c)
      In the event that the Obligations
      hereunder shall be paid in full by or on behalf of Borrower, after the
      Acceleration of this Promissory Note but prior to the Final Payment Date, then
      this Promissory Note shall be deemed paid in full, Lender shall promptly release
      any lien of Lender on the Collateral, and each Lender Nominee shall immediately
      resign from the Board of Directors of Borrower.




14.  **Certain****Rights
      and Waivers**.  To the extent not prohibited by the
      provisions of applicable law, Borrower hereby expressly waives: (a) all
      presentments, demands for performance, notices of nonperformance (except to
      the
      extent required by this Note), protests, notices of protest and notices of
      dishonor; (b) any requirement of diligence or promptness on the part of Lender
      in the enforcement of its rights under this Note; (c) any and all notices of
      every kind and description which may be required to be given by any statute
      or
      rule of law; and (d) any defense (other than indefeasible payment in full)
      which
      it may now or hereafter have with respect to its liability under this
      Note.




15.  **Assignments**.  Borrower
      may not assign or transfer any of its rights or obligations hereunder without
      the express, written consent of Lender.  Any such purported assignment
      or transfer by Borrower without the express, written consent of Lender shall
      be
      null and void *ab initio*.


16.  **Costs
      and Expenses**.  Borrower agrees to pay all costs and
      expenses of Lender, including without limitation all fees and disbursements
      of
      counsel, advisors, consultants, examiners and appraisers for Lender, in
      connection with (a) the issuance of this Promissory Note and advancement of
      principal amount hereunder (which fees and disbursements associated with the
      origination of this Promissory Note shall not exceed $3,500.00), (b) any
      enforcement (whether through negotiations, legal process or otherwise) of this
      Promissory Note, (c) any workout or restructuring of this Promissory Note during
      the pendency of one or more Events of Default, (d) any bankruptcy case or
      proceeding of Borrower or any appeal thereof, and (e) upon the occurrence and
      during the continuance of an Event of Default, any efforts to verify, protect,
      evaluate, assess, appraise, collect, sell, liquidate or otherwise dispose of
      any
      of the Collateral.


17.  **CHOICE
      OF LAW****.** **THE VALIDITY OF THIS NOTE,
      THE CONSTRUCTION, INTERPRETATION, AND ENFORCEMENT HEREOF, AND THE RIGHTS OF
      THE
      BORROWER AND LENDER WITH RESPECT TO ALL MATTERS ARISING HEREUNDER OR RELATED
      HERETO SHALL BE DETERMINED UNDER, GOVERNED BY, AND CONSTRUED IN ACCORDANCE
      WITH
      THE LAWS OF THE STATE OF FLORIDA,** **WITHOUT REFERENCE TO
      CONFLICTS OF LAW PRINCIPLES EXCEPT TO THE EXTENT NECESSARY TO ENFORCE THIS
      CHOICE OF LAW PROVISION.**




18.******Notices**.  All
      communications hereunder shall be in writing and shall be deemed to be duly
      given and received (a) upon delivery if delivered personally or upon confirmed
      transmittal if by facsimile, (b) on the next Business Day if sent by
      overnight courier, or (c) four (4) Business Days after mailing if mailed by
      prepaid registered mail, return receipt requested, in each case to the
      appropriate notice address or facsimile number.




19.  **Independent
      Arms Length Transaction**.  It is understood and agreed
      that this Promissory Note, the Security Agreement and the transactions
      contemplated hereby and thereby were negotiated in an arms length transacton
      separate and distinct from any other transaction or contractual obligations
      and
      are independent of any transaction or transactions between Borrower, on the
      one
      hand, and Lender and any of its affilates or related entitles on the other
      hand.   Borrower further agrees that the contractual obligations
      of Borrower hereunder are in no way dependent or conditioned upon any other
      agreements, contracts or transactions whatsoever unless expressly stated
      herein.




IN
      WITNESS WHEREOF, the undersigned has executed this Promissory Note as of the
      date first written above.




**INVISA,
                INC.**
              
              **By:  /s/Edmund
                C. King__________________________**
              **Name:**Edmund
                C. King
              **Title:**Chief
                Financial Officer