Custom Pressure Sensors for the Aerospace Industry

The aerospace industry is known for having some of the harshest environments on the planet and finding a pressure sensor to withstand those harsh environments can be extremely difficult.  The TR Series pressure sensor and HM Series MEMS sensing element are built to withstand temperatures as low as -40°C and as high as 150°C, making them ideal candidates for the Aerospace industry.  The TR Series and HM series measure pressure via direct media pressure sensing to the backside of the die.  Direct media pressure sensing translates into excellent system design flexibility leading to lower cost and ease of manufacture.

TR Aerospace Image

TR Series – TR Series with Ferrule – HM Series Die

So whether your application is Flight control surface positioning, auto-pilot, jet engine throttle and thrust reverser controls, auto-pilot input, landing gear steering and thrust vector control, turbine guide vane, valve controls, turbine actuators, and engine controls or any other number of Aerospace applications Merit Sensor has the right sensor assembly or MEMS sensing element for you.

Merit Sensor Systems, Inc. has partnered with customers for more than 20 years to design, fabricate, assemble and package reliable, cost-effective piezoresistive pressure sensor solutions.

Merit Sensor offers full-service design capabilities, in-house wafer fabrication, flexible shipping, packaging and assembly, piezoresistive technology (PRT), expansive pressure ranges (0.15 psi to 15,000 psi), complete pressure measurement (absolute, gage, differential and vacuum). Additionally, Merit Sensor is able to provide unparalleled flexibility to customize pressure sensing solutions to fit into our customers’ applications. Most customers in the Aerospace industry require a high level of customization because of the demand of the applications.

Unlike other pressure sensor suppliers, Merit Sensor can provide customers with completely customized pressure sensor designs with large or smaller/limited production runs. Our customers range from pressure sensor transducer manufacturers who are already experts in pressure sensing technology and rely on Merit Sensor for highly stable and sensitive MEMS sensing elements (bare die), to customers who have little to no experience in the pressure sensing world and look to Merit Sensor to assist with a completely custom design and implementation of a pressure sensor that best fits their application.

At Merit Sensor our engineers are application experts. We are ready to help customers design your application to work with a pressure sensor, and/or design a customized pressure sensing solution that works for your application. If you are unsure whether a pressure sensor is right for your application, Merit Sensor can help you make that determination.

More questions? Request a quote for a pressure sensor to meet all your automotive engineering needs.

TR Series for Medical Pressure Sensor Applications

When it comes to your patients, you know what’s best. If you could have everything your way, you would. With Merit Sensor’s piezoresistive pressure sensors, you can.

In 1991 when Merit Medical needed a reliable pressure sensor for one of its devices, their search for the right pressure sensor turned up empty. It was then that Merit Sensor was born and we have been constantly innovating to design and customize industry-specific solutions for all your pressure sensing needs ever since.

Our latest innovation, the TR Series, combines Merit Sensor’s proprietary Sentium MEMS piezoresistive technology with state-of-the-art pressure sensor ASIC signal management for best-in-class performance. The TR Series can be used in air pressure sensors, liquid pressure sensors, and gas pressure sensors. It is designed for harsh media compatibility over extreme and extended temperatures (-40°C to 150°C) with a total error band of less than 1%.

We know there are a lot of unpredictable variables you deal with in the medical industry. Pressure sensors shouldn’t be one of them. Whether used in diagnostic or analysis equipment, our MEMS pressure sensors are designed for unparalleled accuracy and reliability.

Further customization options include:

  • Full-service design capabilities
  • In-house wafer fabrication
  • Flexible shipping, packaging, and assembly
  • Piezoresistive technology (PRT)
  • Expansive pressure ranges (.15 psi to 15,000 psi)
  • Absolute, gage, differential, and vacuum pressure measurement

Explore our pressure sensor customization options further or request a quote on our existing series. Whatever your needs, we are your match. If we can’t build it for you, we’ll find someone who can.

Pressure Sensor For All Your Automotive Engineering Needs?

There’s a reason you are still looking for the right automotive pressure sensor. It’s never been on the market… until now.

At Merit Sensor, we are constantly innovating to find the best design. ‘Best’ might seem like a relative term, but not when it comes to our product. Our latest innovation, the TR-Series Pressure Sensor, is the ideal application for high-performance automotive applications.

When it comes to automotive engineering, there are plenty of pieces to the puzzle. Pressure sensors are one of them. Multiple, to be more accurate. Everything from airbag to oil pressure sensors.

We could talk features all day.

You want to know about PSI? It ranges from 30 to 300 PSI.

Flexibility? The TR-Series is designed with sensitivity, resistance, bridge constraint, and more. But forget features. When it comes down to it, you have to be able to trust a pressure series.

Like you, we never know where your automobiles will end up so we plan for the unexpected and the impossible. From freezing temperatures of -40° C to a boiling 150° C, the TR-Series pressure sensor is designed for optimal performance in almost any temperature for extended periods. The TR-Series is a harsh media sensor, so it’s compatible with any harsh environment the pressure sensor could be exposed do including air, liquid, and gas.

The TR-Series was designed for all your automotive pressure sensor needs.

TR-Series-oil-pressure-sensor

The TR Series pressure sensor is used in the following applications:

  • Transmission pressure sensor
  • Oil pressure sensor
  • Fuel rail pressure sensor
  • EGR/Exhaust pressure sensor
  • Fluid pressure sensor, fuel pressure sensors, and other liquid pressure sensor
  • Fuel tank pressure sensor
  • Fuel vapor pressure sensor
  • Fuel rail pressure sensor

More questions? Request a quote for a pressure sensor to meet all your automotive engineering needs.

How to seal an O-ring to a TR Series Pressure Sensor

Merit Sensor offers a fully calibrated, back side pressure, harsh media, pressure sensor for use with any media which are compatible with Silicon, glass, ceramic and solder. This sensor assembly (TR-Series) was designed to be used with an o-ring, creating a face seal to the back of the sensor.

 

There are many technical considerations that need to be evaluated when designing for an o-ring face seal. To ensure that a good design can be achieved during the first round of development, several factors must be clearly defined.   This information will be critical in subsequent material selections (for both the o-ring and the housing into which it will be inserted) and will be required in the subsequent dimensional and stress analysis.

 

Specifications

Temperature Specification

  • Identify the minimum and maximum end use temperatures for both the operation and the storage conditions.  Will the use temperature will be constant or fluctuating? Will the pressure be changing at the same time?

 

 

 

Pressure Specification

  • Identify the minimum and maximum use pressures. Will the pressures be all positive, all negative or a combination of both positive and negative? Will the pressures be fluctuating or constant? Will the temperature be changing at the same time?

 

 

Media Specification

  • Identify the media that will be in contact with the sensor. What chemistries do they contain? Are they compatible with Silicon, Borosilicate Glass, 96% Alumina Ceramic and Solder?   What will be the exposure conditions (temperature, pressure, duration, concentration, etc.) Be sure to think about both sides of the sensor. The backside will be exposed to the harsh media. The front side will be exposed to some other environmental conditions. Be sure that the “top side” is protected from the harsh media.

 

http://www.applerubber.com/src/pdf/chemical-compatibility.pdf

 

O-Ring Options

Material Options

  • The o-ring material should be selected based on the information specified above. The o-ring softness should be selected base on the maximum use pressure and the resulting packaging stresses. A soft o-ring will provide a very compliant seal which will result in very low induced packaging stresses but may not be able to seal well at high pressures. A hard o-ring conversely would seal well at high pressures but may also induce high packaging stresses. Different o-ring materials have different temperature handling capabilities. The glass transition temperature of the polymer will limit the lower functional operating temperature of the o-ring. The temperature at which the polymer begins to decompose or soften will limit the upper functional temperature of the o-ring. It is also important to look at the media compatibility of the different o-ring polymers. The longevity of the o-ring and the amount of swell that the o-ring will experience will be different depending on the o-ring material and the media. It may be difficult to find the exact right material to match all of the specification requirements.

 

http://www.applerubber.com/src/pdf/general-properties-of-orings.pdf

 

 

 

Geometry Options

  • After the material selection, the determination of the o-ring size (OD and cross-section) is the next thing to consider. The o-ring should accomplish several different goals. The o-ring must ensure that the media will not leak at minimum and maximum pressures. The o-ring must ensure that the media does not leak at minimum and maximum temperatures. The o-ring should be chosen to minimize package stress buildup during pressure and thermal cycles.
  • There are several different o-ring geometries that can be used for face sealing. Each of them has advantages and disadvantages. The most common and cost effective o-ring geometry is the standard circular cross-section. This geometry can be used for both positive and negative pressures. To assist with high pressure sealing, backer rings can be used to prevent issues with squeeze-out. In addition to the circular cross-section, there are “X” and “U” shaped o-ring cross-sections. The “U” shaped o-ring comes in two configurations that could work as a face seal (inward facing channel for positive pressure applications, outward facing channel for negative pressure applications). The “X” cross-section will work in either application.

 

 

O-Ring Gland Options

Counter Boar Gland

  • The counter bore gland is the most common o-ring gland. It is relatively simple to design and manufacture. The gland depth and width can be tailored to work with the specific application specifications. Items that need to be considered are the squeeze percentage, the swell and the coefficients of thermal expansion.

 

 

Dovetail Gland

  • The dovetail gland is the most complicated o-ring gland. It is difficult to design and is expensive to manufacture. The primary benefit of this gland design is that it will assist in holding the o-rings in place during assembly. It is not recommended for small o-rings. This design is even more sensitive to the squeeze percentage, the swell and the coefficients of thermal expansion.

 

Suggested Engineering Analysis and Verification

To ensure that the o-ring will seal properly over the full temperature and pressure use ranges, several different analyses should be carried out. It is important to look at static forces, dynamic forces and the effects of temperature on each.

 

Static and Dynamic Analysis

  • It is important to calculate the dimensional changes that will happen with temperature. The OD, ID and cross section diameters of the o-ring should be calculated at the Min and Max temperatures. The width and depth of the gland should be calculated for Min and Max temperatures.   The o-ring squeeze should be calculated at each of these extremes to ensure that the gland dimensions are adequate. Be sure to take into consideration the swell for the o-ring material base on the media in contact with the o-ring. Based on these dimensions, the zero pressure stresses on the package can be estimated.
  • The static model should then be used to evaluate the stresses during changes in both temperature and pressure. Based on the output of this analysis, a suitable combination of o-ring size, o-ring material and gland dimension can be selected to provide the optimal solution.

 

Because each application is a very unique combination of temperature, pressure and media, it is recommended that verification testing be carried out by the customer to ensure that the o-ring material, o-ring cross section and the gland dimensions will provide a robust solution in the final application.