# What is micro-electromechanical systems (MEMS)?

I know definition but how would you explain to complete layik ( as me ) what is MEMS and how it is used.

Examples: Silicon nanopore membranes (SNM) have been prototyped from silicon substrates by an innovative process based on MEMS technology.

• Hey Mahendra, I understand but I am unfortunately not smart enough to understand such a complicated concept, @MahendraGunawardena it shame since I plan to use it – SSimon Nov 17 '15 at 14:35
• I was hoping you can expand in context of nanopore fabrications, @MahendraGunawardena – SSimon Nov 20 '15 at 11:35

One way to think of MEMS is regular mechanical systems, but at a very small scale. Often these tiny systems are fabricated using technology developed for making silicon electronic chips, like nanometer-scale photolithography and etching.

However, describing MEMS as just downscaled regular mechanical systems is doing the concept injustice.

Various physical properties scale differently with linear dimension. For example, simply scaling a ant to the size of a elephant wouldn't work. The mass the legs have to support is proportional to the volume (cube of the linear scale), but the strength of the legs only proportional to their crossectional area (square of linear scale). Such a system can't be scaled up linearly and still function as the original.

As a result of different scaling of different physical properties to the tiny dimensions of MEMS, some things we do routinely at the human scale are impossible, but new things are possible that would be impractical at human scale. For example, rotary electric motors with conventional windings would be extremely difficult in MEMS. However, at such short distances, the electrostatic force can be harnesses much more easily, and MEMS motors using it are quite possible and efficient. At nanometer distances, just a few volts can cause quite significant forces relative to the much much lower mass (remember, mass scales with the cube of linear dimension) of the parts.

The above is just one example, but illustrates how you enter a different world at micrometer or nanometer dimensions.

• Thank you very much Olin, What is alternative for MEMS ( using it for nanopore fabrication ) TEM, ion beam ? – SSimon Nov 17 '15 at 14:40

MEMS is a semiconductor based process that can create miniature structures in silicon. When these structures (sensors) are subjected to mechanical stresses (pressure, acceleration, yaw etc) they are able generate electrical signals. These signals are conditioned using an Application Specific Integrated Circuit (ASIC) to create a sensor system.

Below are some of images representing manufacture of a MEMS differential pressure sensor.

The above silicon structure electrically is represented as below.

The piezoresistive sensing elements are structured to form a wheatstone bridge. When pressure is applied on a thin diaphragm the mechanical stresses are converted to an electrical signal using a wheatstone bridge resistor structure. This signal then processed using an ASIC to create a stable and predictable electrical signal. The electrical output is used by other device such as a micro-controllers.

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