Choosing the Right Sensor for Measuring High

Pressure

This webinar will be available afterwards at

designworldonline.com & email

Q&A at the end of the presentation

Hashtag for this webinar: #DWwebinar

Before We Start

Moderator

Randy Frank Design World

Presenters

Ian Abbott TERPS, GE Energy

Karmjit Sidhu American Sensor Technologies

Marek Wlodarczyk Optrand

Wendell McCulley InterMEMS

Choosing the right sensor

for measuring high

pressure Karmjit S. Sidhu

American Sensor Technologies Inc

Www.astsensor.com

Design considerations for high pressure sensors

• Hermetic seal against media

• Rugged and durable

• Wide media compatibility

• Wide operating temperature range

• High cyclic life

• High proof and burst pressure ratings

• Long term stability

• Low non repeatable errors - hysteresis and no repeatability

• High degree of compensation

Typical high pressure applications

• Hydraulics - 500PSI to 15000PSI

• Oil & Gas - 500PSI to 20000PSI

• Diesel injection - up to 45000PSI

• Compressed Hydrogen - 2500PSI to 15000PSI

• High pressure oxygen - up to 6000PSI

• Water jet cutting - up to 72000PSI

• Gas chromatography - 500PSI to 20000PSI

• CNG systems - up to 4000PSI

• Fire suppression systems - 500PSI to 3000PSI

• Refrigeration - 500PSI to 1000PSI

• Filtration

Krystal Bond Technology for high pressure

• One piece design - no welds, no O-rings, no fluid filling

• High temperature inorganic bonding of silicon to metals

• Wetted materials - 17-4PH and 316L stainless steels, Inconel 718, Hastelloy C276, Titanium CP4

• Low operating strain

• Thick membrane

• High output of 40mV/V

• No p-n junctions - stable over wide temperature

• Very low EMI interference

Cross section of Krystal Bond Sensor

Silicon sensing elements glass bonded to

stainless steel diaphragm

Fiber-Optic

Pressure Sensors

for

Environments

18

Schematic Diagram of Optrand Fiber Optic-Based Pressure Sensor

19

Pressure Range: 0-150, 0-250, 0-350, 0-3000 bar

Burst Pressure: > 4 range

Tip temp.: -40oC to 380oC (480oC)

Conditioner temp.: -40oC to 125oC (140oC)

Accuracy: 1-2% FSO

Frequency range

Dynamic Sensor: 0.1(1) Hz to 20 (60) kHz

Static-Dynamic: 0 Hz to 20 kHz

Service life: 0.5B -5B pressure cycles,

10k- 30k hours

High-Pressure High-Temperature

Pressure Sensor Key Specifications

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Pressure Sensors Targeting Internal

Combustion Engines • Dynamic sensors for use in (1) engine R&D and (2)

production gasoline, diesel, natural gas, jet fuel engines used in passenger car, light- and heavy-duty truck, off-highway, marine, gen-set, ship, locomotive, or light aircraft applications

• Two versions offered: o Signal conditioner connected to sensor head by ruggedized

~few meter-long fiber optic cable; targeting engine R&D and large engines

o Signal conditioner located on top of sensor head; targeting automotive OE applications

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Sensors Targeting Harsh Environment

Industrial and Turbine Applications • 480oC-rated static-dynamic sensor for turbines • 420oC-rated static pressure sensors for Plastic Melts with

flush mounted diaphragms as small as 1mm in diameter with M4x0.6 thread

• 380oC-rated all fiber optic static-dynamic pressure sensor with fiber optic cable up to hundreds meters-long for monitoring of industrial circuit breakers and transformers

• 280oC-rated all fiber optic static-dynamic pressure AND temperature sensor in one package with fiber optic cable up to ~1 Km for oil-gas exploration, geothermal well & volcano monitoring

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Current Sensor Packages

M12x1.25

M4x0.6

M3x0.5

F1.8mm

M8x1 M4x0.6

Wendell McCulley President

•At first glance High Pressure Sensor packaging seems to be more forgiving than Low Pressure.

•Die attach can be done with “Harder” materials with less effect on TCOffset.

•Overpressure however is a Big Issue.

•Do you choose to use less traditional packaging methods (e.g. NASA SSME)

High Pressure Presents some very Special Considerations

•Topside Applied Pressure with RTV Die attach.

•Oil Filled with Stainless Steel Isolation Diaphragm

•May require a Ceramic or other material as an Interposer

•Common Mode Pressure Considerations

Traditional packaging

Extremely hard to accurately Model the Performance of Corrugated Diaphragms since they are inherently Non-linear, and in the Large Deflection Regime

Provides Media Isolation, Must be strong enough to withstand High Hydrostatic pressure, but must be flexible enough to take up Oil expansion over Temperature

•Do you choose to use less traditional packaging methods (e.g. NASA SSME)

•Hard Eutectic Die Attach

•Metal or Nitride V-Ring Seals

•Must withstand cryogenic temperatures -425⁰F to 250⁰F

•Use of Materials with closely matched Temperature Coefficient of Expansion

•Electron Beam Welded

Creative High Pressure packaging

•Use of Integrated Strain Gauge to measure flexure of the overall Chip

•Correction of Pressure Sensor Measurand for Chip flexure.

•On Chip Thin film Laser Trimmable Resistors.

Creative Electronics, Compensation and Calibration

•Silicon is a mode 1 Fracture Material

•Silicon and glass are Pulled from the central region of the chip

•Looks similar to the hole a BB makes in glass

•Diameter is directly related to the Radius of transition from Tension to Compression and can be controlled by judicious design.

•Design Choices depend on many considerations

•Slab Vs. Diaphragm Design

•Aspect Ratio

Backside Pressure Failure Mode

•Both have the same Die Size and Thickness

•Both have the Same Diaphragm Edge Length to Thickness Aspect Ratio

•Both have Approximately the same Pressure Sensitivity.

Two Different Design Realizations for a 1000 PSI Pressure Sensor

(A Case Study)

•In the case of the Larger Diaphragm it is Completely off the Diaphragm.

•In the case of the Smaller Diaphragm it is just on the Diaphragm near the Edge.

The ideal location “Sweet Spot” for the Piezoresistors is Very Different

•The Larger Diaphragm is also thicker, and therefore must be more Robust, Right?

•By choosing the smaller Diaphragm we can make the overall Die Size much smaller, Right?

Why do we Care?

•For Backside Applied Pressure, the Large Diaphragm will Fail at much lower Pressures.

•The Smaller Diaphragm needs to be part of a Large Die to support higher Burst Pressure.

In the World of High Pressure Things are often Counter-Intuitive.

•Often Counter-Intuitive

•Highly Interdisciplinary requiring a Deep Knowledge of:

•Materials

•Fracture Mechanics

•Piezoresistivity

•Packaging

•Media Compatibility

•Still a bit of a Black Art

High Pressure Sensor Design

•Specific knowledge of High Pressure Sensor Design & Manufacturing

•Has the Tools necessary to develop high performance devices.

•Non-linear Large Deflection Finite Element Analysis (FEA)

•Process Modeling (SUPREM)

•Wafer Processing

•Packaging

•Excels in Design for Manufacturability

InterMEMS Inc. Capability

Summary

Questions?

Design World Randy Frank r.frank@ieee.org Optrand

Marek Wlodarczyk president@optrand.com

American Sensor Technologies Karmjit S. Sidhu kssidhu@astsensors.com

TERPS, GE Energy Ian Abbott ian.abbott@ge.com

InterMEMS Wendell E. McCulley wmcculley@intermems.com

Thank You

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