Tag Archives: pressure sensor

NEW Media Isolated Millivolt Pressure Sensors

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll be discussing our new media isolated pressure sensors.

NEW Media Isolated Millivolt Pressure Sensors

All Sensors has a brand new offering of media isolated pressure sensors. The first line released is the ceramic CPM 602 Series. These new pressure sensors offer design engineers excellent performance in various applications, especially for low-cost solutions.

Product Features

  • Pressure ranges 30 to 6000 psi gauge
  • Piezoresistive monolithic
  • Excellent chemical resistance
  • Supply voltage 2 to 30 VDC
  • Total error better 4% FS

Applications

  • Medical
  • Environmental Controls
  • Plant and Mechanical Engineering
  • Automotive

See more information here. Datasheet download here.

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Han Mai, Senior Marketing Specialist, All Sensors Corporation (hmai@allsensors.com)

Critical Flight Measurements Using Pressure

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll be discussing critical flight measurements using pressure.

Critical Flight Measurements Using Pressure

Amplifying the low level signal from a higher pressure range sensor for a low pressure application can frequently lead to unacceptable noise problems in the application. This can occur if the sensor supplier performs this task as part of an amplified and signal-conditioned product offering or if the customer performs the amplification and signal conditioning. The limitation is inherently in the sensor die. Specially designed lower pressure range sensors, such as All Sensors DLVR Series mini digital output pressure sensors offer a solution to the noise problem.  The low mass, high-sensitivity die are less sensitive to errors due to vibration or changes in time, temperature and position.

All Sensors’ CoBeam2 TM die technology achieves a high level of pressure sensitivity without using boss structures and larger die topologies commonly used in microelectromechanical system (MEMS) designs. This design approach significantly reduces gravity and vibration sensitivities. As shown in Figure 1, CoBeam2 technology combines bonded strain gage sensor insight with state of the art MEMS processing.

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Figure 1 MEMS pressure sensor die using CoBeam2 technology

Figure 2 shows active dual-die compensation with electrical cross coupling of the sensors’ outputs and pneumatic cross coupling of the pressure used in the DLVR Series and other All Sensor products. By performing both electrical and pneumatic cross coupling, the signal strength is not reduced and the common mode error compensation is optimized. Some products use just the electrical cross coupling. Pressure Point 4: Dual Die Compensation for MEMS Pressure Sensors provides more details. Combined with CoBeam2 Technology, the amplified, digital output sensor reduces many errors associated with pressure measurements.

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(a)                                                                                      (b)

Figure 2  (a) Electrical cross coupling compensation of active die (Die 1) using a reference die (Die 2) and (b) pneumatic cross coupling compensation using fluidic channels in the pressure sensor package.

Drones, multicopters, quadcopters, small unmanned air vehicles (UAVs) and micro air vehicles (MAVs)  are not only the rage in modern flying craft, they are among the applications that can benefit from the improved sensor performance of a small form factor MEMS sensor.  Low pressure sensors such as the 1 inH2O DLVR-L01D up to the 10 inH2O DLVR-L10D can be used for measuring differential pressure on the wing in multiple locations to provide improved control and stability. Higher pressure ranges are also available.

Wind tunnel testing has traditionally used several pressure sensors on the wings of a test aircraft to provide a pressure-based estimation of the flow field above an airfoil. Recently, for increased control in drones, aerodynamics-based feedback using onboard active flow control schemes relies on a set of pressure measurements taken across the aircraft through pressure ports and through multi-hole probes. The aerodynamic feedback can be especially useful when switching control modes during various flight conditions.

Highly turbulent situations can also pose attitude control difficulties for fixed-wing MAVs. In Bioinspired Wing-Surface Pressure Sensing for Attitude Control of Micro Air Vehicles, researchers are investigating alternate technique using pressure sensors to solve this problem.

Other flight measurements can benefit from highly stable pressure sensors. For example, the DLV-015A DLV Series mini digital output absolute sensor can provide the barometer or altimeter readings in these same aircraft.

CoBeam2 is a trademark of All Sensors Corporation.

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Han Mai, Senior Marketing Specialist, All Sensors Corporation (hmai@allsensors.com)

The Pressure for Fresh Water

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll be discussing the role pressure plays in the desalination efforts in California.

The Pressure for Fresh Water

With water shortages occurring in all regions of the world and especially in California, new sources of water are being explored.  In some cases, the new source uses an old approach. Desalination of sea water is getting new attention after being shelved for decades in Santa Barbara. Also, San Diego is building the nation’s largest ocean desalination plant that will be completed in 2016. Pressure is an integral part of turning sea water into drinkable/usable water.

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Courtesy Bay Area News Group

A reverse osmosis (RO) process is used to separate the dissolved salts in a saline solution by flowing the liquid through a water-permeable, pressure-driven membrane. The pressure required depends on the type of membrane and the desalination being performed. For example, the desalination plant on Catalina Island uses 900 psi to treat ocean water. Treating underground brackish water only requires 200 to 300 psi.

As shown in the table, there are four categories or classes of pressure-driven membranes for desalination.

 Membrane Type Pore Size Transmembrane Pressure Application 
Microfiltration (MF) 0.1 – 3 micron 1- 30 psi Turbidity reduction and bacteria removal
Ultrafiltration (UF) 0.01-0.1 micron 1- 30 psi Same as MF as well as removing viruses and some color, odor and organics
Nanofiltration (NF) < 0.002 micron 75- 150 psi Natural organic matter (NOM) removal
Reverse osmosis (RO) non-porous 150-500 psi Removing monovalent salt

MF/UF membranes are being increasingly employed in the desalination process to shield other membrane types from suspended solids and larger colloidal material that are detrimental to their performance. As part of the control and monitoring process, the differential pressure is sensed across the membrane at each phase.

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Han Mai, Senior Marketing Specialist, All Sensors Corporation (hmai@allsensors.com)

Sleep on a Layer of Pressurized Air

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll discuss air pressure in mattresses and air beds.

Sleep on a Layer of Pressurized Air

Air mattresses and air beds use air pressure to provide an adjustable comfort level to users.  An air mattress can be easily stored in a small amount of space when it is deflated and brought back into service by “simply” inflating it.

For users that do not want to use lung power for the inflation process, how much pressure should be applied? Most manufacturers seem to recommend something around 1 psi maximum. For measurement purposes, a 5 psi pressure sensor can easily handle this range.

The pump can be built in or external to the mattress or bed. One inflator pump supplier offers a high-volume, low-pressure inflation with a pump pressure of 52 psi and pump volume of 3047 cubic feet/minute. With 1 psi as a max setting, the mattress can be filled quickly and its rating easily exceeded.

However, with this low level of internal pressure, barometric pressure can impact the feel and comfort level and even the life of an air mattress. One manufacturer recommends, “Partially deflate your mattress when leaving it inflated during the day, especially when in a car or tent on a hot day. (Barometric pressure and significant changes in weather and temperature will affect your air mattress’s inflation and possibly damage it.)

Air beds that have a dial setting where the user can determine his or her ideal comfort level may have an inappropriate setting if the weather changes significantly.

According to its website, “Comfortaire designed the first air bed over 28 years ago.” One of their beds even has a psi reading to determine the right comfort level.

With air pressure providing the desired comfort level, the old saying of “sleep tight” may need to be rephrased to “sleep at your ideal pressure.”

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Figure courtesy of Comfortaire.

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Han Mai, Senior Marketing Specialist, All Sensors Corporation (hmai@allsensors.com)