Presentation on theme: "Attachment 11 Radio Frequency (RF) Stability of Medical Implants October 1, 2006."— Presentation transcript:
Attachment 11 Radio Frequency (RF) Stability of Medical Implants October 1, 2006
Attachment 12 Role of Chris Fuller at Medtronic Developed and executed majority of Engineering Verification Tests (EVT) for early version of Concerto including all stability tests. –Early version EVT tests used to justify minimal Concerto testing even though all Concerto versions tested unstable. Developed Design Verification Tests (DVT) for Concerto RFIC and assisted development for Base-station radio. –Executed stability testing for Concerto RFIC. Developed production test plans for Concerto implant and it’s base-station. Bottom line: Medtronic accepts my test results that passed, but rejects my test results for critical safety parameters that failed and refused to conduct commercial standard critical safety tests that are documented in the test plans. –Medtronic falsely claims instabilities do not matter or conditional stability is achieved.
Attachment 13 Examples of insufficient product specifications/evaluations Source: http://www.enm.bris.ac.uk/research/nonlinear/tacoma/tacoma.html#photos Magnetic switch for Guidant cardiac defibrillators Ventak Prizm 2 DR (model 1861), Contak Renewal (model H135) and Contak Renewal 2 (model H155), Ventak Prizm AVT, Vitality AVT, Renewal AVT, Contak Renewal 3 and 4, Renewal 3 and 4 AVT and Renewal RF. Battery for Medtronic Marquis VR/DR and Maximo VR/DR ICDs and the InSync I/II/III Marquis and InSync III Protect CRT-D Tacoma Narrows Bridge, November 1940
Attachment 14 Examples of insufficient product evaluation/information Chernobyl, April 1986 Source: http://news.bbc.co.uk/1/hi/sci/tech/5173310.stm Chernobyl: Plant designers aware of instability triggers, but did not inform operators. Medtronic: Concerto implant designers aware of instabilities, but do not understand triggers. Medtronic refuses to inform physicians and operators.
Attachment 15 Instabilities which have occurred during various tests performed by Chris Fuller Non-Medtronic instabilities (commercial and government): –Amplifier instability burned up circuit on X-ray camera electronics –Amplifier designed for 9 GHz unstable at 18 GHz –Amplifier designed for 400 MHz oscillated at 8 GHz –Uncontrolled instabilities and excessive battery current in receiver IC designed for 10.7 MHz Medtronic instabilities: –Medtronic Concerto Implant –Medtronic Concerto Base-station radio Only Medtronic instabilities went to production uncorrected.
6 What is RF Instability? Instability = loss of control Instability = unpredictable affects –May prevent other circuits from behaving properly Stability = critical for high-reliability devices AMP FEEDBACK + INPUT Step 3: Input and feedback overlap and add together maximally OUTPUT Step 4: Output increases until: -Device destruction -Power supply limits -Uncontrolled oscillation Feedback from: -Circuit components -Circuit board & traces -Impurities Step 1: Input signal is amplified Step 2: Part of amplified signal is fed back to input of the amplification device.
7 What are Uncontrolled Oscillations? RF circuit loses control of it’s operations Examples: Desired: DC signal, no oscillations Result: Uncontrolled Oscillations Desired: Controlled oscillations Result: Uncontrolled Oscillations
Attachment 18 Observed RF Instability Affects Circuitry does not perform as designed –Unpredictable performance Unpredictable effect on other circuits –May prevent other circuits from behaving properly Uncontrolled oscillations Excessive battery current drain –Circuit sometimes shorts out power supply Burns up unstable circuitry or other circuitry
9 Medtronic should have performed commercial standard instability tests Monte Carlo simulation of circuit –Verify stable vs. production tolerances Load pull instability tests –Vary circuit impedances to detect instabilities Opas sweep tests –Large and small signal stimulate circuit to verify stable On-board stability tests –Measure small signal reflections to verify stability S-parameter stability tests –Measure circuit characteristics to verify stable Perform each test above on each accessible RF circuit Stability = Most studied RF parameter except at Medtronic
10 Why does Medtronic have a Problem? Testing less than Commercial High-Rel. Only partial load-pull stability performed on final Integrated Circuit used in Concerto –Concerto RFIC exhibited indications of instabilities –Stability not studied for some frequencies and conditions at which Concerto may be unstable –Medtronic falsely claims Concerto is conditionally stable Standard stability verification not performed for Base- station radio for Concerto (i.e. RFT or 2090W). –Base-station radio for Concerto exhibited instabilities during pre- production testing. Stability verification was far less than what a cell phone basestation manufacturer would perform. Effects of an instability in Concerto or it’s base-station radio on implant therapy or alternate communication (i.e. Telemetry B) functions have not been evaluated.
11 Conclusions Stability of Concerto and it’s Base-station are critical. Instability of Concerto or it’s Base-station may result in life- threatening conditions. Stability testing was far less than what would be performed for a commercial high-reliability cell phone radio. The Concerto implant and the base-station radio that communicates with Concerto both exhibited instabilities. Most Concerto stability tests have been disavowed by engineer that developed and performed the tests. Medtronic is risking the lives of patients by not properly verifying RF stability. RF stability is only one of many problems with Concerto and it’s base-station (i.e. 2090W). Medtronic can understand and correct the stability problems experienced by Concerto and it’s base-station communication device, but chooses to do nothing.