Advantage of using MEMS type Tiltmeter over EL type Tiltmeter

MEMS

MEMS is known as a Micro Electro-Mechanical System, and is composed of electrical and mechanical components together on a chip and is assembled in a tiltmeter.

ER tilt meter is built around a precision accelerometer mounted inside a stainless steel housing together with suitable signal conditioning circuit.

The accelerometer senses the force of acceleration due to gravity which is maximum when the accelerometer is rotated to full 90 degree tilt position and is zero (minimum) when the tilt angle of the accelerometer is zero.

For all in-between angles of tilt, the force experienced by the accelerometer is equal to the product of sine of the tilt angle and the acceleration due to gravity.

The tilt sensor thus provides a bipolar DC voltage output proportional to the sine of the tilt angle measured by the tilt meter. The output is zero volts for a truly vertical sensor.

Few of the advantage of MEMS tilt sensors are mentioned below:

• Temperature effect on the sensor is very small compared to Electrolytic although temperature effects of the system and in particular the fixings should always be considered.
• Measuring range larger
• Sensitivity is higher
• Provision of dual axis (Biaxial)
• Smaller in size
• Have lower power consumption
• More sensitive to input variations
• Cheaper due to mass production
• Less invasive than larger sensors like electrolytic
• Very much supportive to the digital, real time world automatically and transmits the accurate and reliable data.

Electrolytic

The Encardio-rite model electrolytic tiltmeter is housed in an aluminium die cast enclosure and is generally used as a stand-alone unit for measuring tilt. It is either attached directly to the structure whose tilt is to be monitored using suitable mounting brackets or fixed to vertical beams.

Electrolytic tiltmeters are available with either raw half bridge output (output option R) or voltage output (output option V). The raw half bridge output sensors require a suitable datalogger that can accept half bridge sensors with ac excitation.

So only specific dataloggers can be used for electrolytic sensors.The raw half bridge output option is popularly used with beam sensors that are used in arrays as a number of sensors in close proximity allows easy use of a datalogger.

The voltage output sensors can be read with any digital voltage measuring device like digital indicators or multimeters but do require an additional very low current dc power source. A 9 V dc battery is sufficient to power the tilt sensor. Most commercially available dataloggers generally have some provision for supplying the required power to the sensor. Although voltage output sensors are costlier their output can be read by low cost digital voltmeters.

The voltage output option is more popularly used with EAN-30EL which is mostly used as a stand alone tilt sensor and the sensors are generally spread over a fairly wide area.

Encardio-rite Model Electrolytic tiltmeters are used in applications where small tilts needs to be measured specifically of the order of half a degree, with a high resolution. It uses a ceramic encapsulated electrolytic bubble level sensor as its sensing element.

One of the disadvantages of electrolytic sensors over MEMS is that they are significantly affected by temperature but are more resistant to vibration over MEMS.

Biaxial or Uniaxial

All Tiltmeters have the option of being supplied with Single or Dual axis Tilt boards. Biaxial is generally slightly more expensive so depending on your application or measurement requirements, you are able to make a decision on which would be better suited and potentially save some cost where you can get by with Single Axis measurements.

Water resistant

Standard Tiltmeters are supplied in an IP66 enclosure meaning they are protected against strong jets of water (i.e. heavy rain). If there is any chance at all of the Tiltmeter becoming submersed, a Submersible Tiltmeter (IP68 to 200m) should be used.