Exhibit 10.33

AMENDMENT NO. 2 TO

PURCHASE AGREEMENT – SERVICES PHASE 2 # CW1882970

BETWEEN

INTEL CORPORATION AND IMPINJ, INC.

For valuable consideration, the receipt and sufficiency of which the parties hereby acknowledge Intel Corporation (“Intel”) and Impinj, Inc. (“Impinj”) hereby amend the above referenced Purchase Agreement – Services Phase 2 dated on or about December 23, 2009 # CW1882970 (the “Agreement”) as set forth hereafter.

The Effective Date of this amendment (“Amendment”) shall be April 20, 2011.

The new Expiration Date of the Agreement shall be March 31, 2012.

Unless provided otherwise in this Amendment, each term appearing in this Amendment shall have the same meaning as given in the Agreement.

The term “Service(s)” shall be expanded to include the work to be performed as set forth in Addendum “C”, including any deliverables set forth in Addendum C resulting from such Services.

By executing this Amendment, Intel and Impinj are amending the Agreement to:

Include Addendum C (Hannegan1 *** and Hannegan2 ***) of the Agreement which is attached hereto and incorporated herein by this reference.

As amended by this Amendment, all provisions of the Agreement shall remain in full force and effect. In the event of a conflict between this Amendment and the Agreement, this Amendment shall take precedence.

ADDENDUM C

Hannegan1 *** and Hannegan2 ***

Statement of Work for Purchase Agreement – Services:

This SoW describes work that Impinj will perform to *** Hannegan1 and *** for Hannegan2. This SoW:

This project has two goals:

The project team shall comprise personnel from Intel and Impinj.

Intel shall:

Impinj shall:

Acceptance Criteria: Objective acceptance criteria, agreed to in writing by both Intel and Impinj, for deliverables under this SOW.

The project scope shall be for Impinj to *** Hannegan1 and develop *** for Hannegan2.

The project fee shall be $***, payable as set forth in the Project Milestones and Deliverables table below. Intel will also reimburse Impinj for additional project-related costs actually incurred by Impinj and approved in advance by Intel, such as travel expenses.

The “Acceptance Criteria” for each milestone are defined in the Project Milestones and Deliverables table below. A deliverable will be accepted if it substantially conforms to each of the Acceptance Criteria for that deliverable. Intel will provide notice of acceptance or rejection of each deliverable within 15 days following Intel’s receipt of the deliverable, and if such notice is not provided within 15 days following receipt the deliverable will be deemed accepted.

Impinj will provide the deliverables under this SoW “as is” and without warranty of any kind, and Impinj disclaims any implied warranties. Each party’s liability under this SoW will be limited to the total amount of fees paid or payable by Intel as set forth above, and neither party will have any liability for incidental or consequential damages under this SoW. Notwithstanding the foregoing, this Section regarding limitation of liability shall not apply to claims or damages arising from death or personal injury or tangible property damage, from any breaches of obligations of confidentiality, or payments to third parties under the indemnity with respect to hazardous materials.

The project managers are:

The project milestones shall be as defined below. Prior to Impinj’s completion of work, Intel shall review and either accept or request reasonable changes to the deliverables. Impinj shall make reasonable efforts to accommodate Intel’s requested changes.

Appendix C-1 – Hannegan1 Requirements

Hannegan1 ***

***