J500 Materials Science and Engineering

This effect is employed in a scenario where energy is converted between mechanical and electrical form.  It was discovered by French brother Pierre and Paul-Jacques Curie in the year 1880's; piezo is a Greek word which means pressure hence pressure is the backbone of the operation of this technique (Beeby 2004, p. 212).  If pressure is applied to a polarized crystal, there will be a mechanical deformation which leads to an electrical charge. There are materials used in making a device which can convert mechanical force into electrical signals. These materials are known as piezoelectric materials. The foundations of progressive piezoelectric materials are solid made of lead zirconate titanate (PZT) which is highly amended by different types of constituents and dopes.

These material have several properties like; high dielectric constant value, they possess spontaneous polarization in many zone or domain, dielectric should increase with increase in temperature, availability of hysteresis twist found in polarization- electric field strain-electric field curves, ferroelectric properties vanish beyond a specific point in the dielectric constant-temperature curve, this is also known as the Curie curve (Bhat 2013, p. 132). These materials used in making the piezoelectric are the following;

Ferrosoft materials:

These materials should have a medium, low and a high dielectric constant value. The materials are best for a high-sensitivity receiver and less power emitters of both ultrasonic and sonic signals when both electrical signals and mechanical forces are low and negligible losses. These materials are used in making several types of transducer, transducer, and actuators (John 2003, p.124).

 Synthetic ceramics:

These are randomly concerned with gain should be ferroelectric to show piezoelectricity.  The piezoelectric which is macroscopic is likely to be surfaced polycrystalline non-ferroelectric piezoelectric substantial like AIN and ZnO. Some of these ceramics material include; Barium titanate (BaTiO₃), Lead zirconate titanate, Potassium niobate (KNbO₃) (Pb[Zr_xTi_1−x]O₃  Barium titanate (BaTiO₃),  Pb₂KNb₅O₁₅ , Zinc oxide (ZnO), Sodium tungstate (Na₂WO₃) (Gao 2010, p. 214).

Lead-free piezoceramics:

Lead-free piezoceramic is a group of material which include, Sodium potassium niobate((K,Na)NbO₃) . The material has been tried and proved to keep a high mechanical quality factor Q_m ≈ 900) with higher vibration intensities where the mechanical quality factor of a hard PZT damages in such situations.

Porous material:

These materials feature a big range of temperature and find the use of ultrasonic transducers, defectoscopy, vibrating measuring, thickening gauge, medical diagnosis and hydroacoustic.  

Piezoelectricity is the electric charge which collects in certain solid substances, for example, certain ceramics, crystals, genetic matter like DNA in rejoinder to applied mechanical strain. The piezoelectric effect is taken as the rectilinear electromechanical collaboration with electrical state and mechanical state in crystalline constituents without inversion symmetry (Gaura 2011, p. 231). This effect is a reversible action in that materials will display the direct piezoelectric effect, and it also displays the reverse piezoelectric effect. The figure below indicates how the piezoelectric sensor.

                                     

The material used in the piezoelectric pressure sensor is a diaphragm made on a silicon substrate that will bend once pressure is applied. There will be deformation in the lattice of the crystal of the diaphragm due to the bending which took place.  The deformation will generate an adjustment/change in the piezo resistors' band structures which are on the diaphragm; this will lead to change the material's resistivity (Gautschi 2013, p. 123). The change can increase or decrease depending on the resistor’s orientation.

History of the development of piezoelectric pressure sensors

This technology is traced back since early 1880’s. Between the year 1880 and 1882, there was the first experiment which was done on demonstration of connection the crystallographic structure and macroscopic piezoelectric phenomena which were carried by the French founders Jacques Curies and Pierre (Gregory K. McMillan 2003, p. 244). Their experiment entailed decisive measurements of the surface charges which appear on particularly made crystals. Their results were an acknowledgment to their creativity and perseverance since the results were got just from tinfoil, wire, glue, magnet and jewelers. This discovery of the Curie brothers was considered great in the scientific circle, and the discovery was named piezoelectricity so that it could be differentiated from other fields of scientific phenomenological skills like electricity  created due to contact and also the piezoelectricity ( which is electricity obtained by heating ).  The brothers did not foresee crystals demonstrating the direct piezoelectric effect (electricity derived from applied pressure) during this period (Iniewski 2012, p. 366).

From the year 1882-1917 (  A laboratory curiosity), during this period which was just two years after collaborative work in the European scientific field, the basic piezoelectric uses science was recognized. During this period there was the identification of piezoelectric crystals on the foundation of the unequal crystal structure, there was also an alterable exchange of mechanical and electrical energy, and the application of the thermodynamics of enumerating complex connection,   thermal, electrical and mechanical variable.

 After 25 years, a lot of work was undertaken to ensure this essential develop into a flexible and a complete structure which defined completely  many crystal classes in which piezoelectric take place. It also defines eighteen likely macroscopic piezoelectric constants supplementing a severe thermodynamic action of crystal solids by the use  of appropriate tensional analysis (John P. Dakin 2006, p. 422).  Voigt’s ( Lehrbuch der Kristal LPG Sik"  was developed during 1910, and it was the most allusion work symbolizing the appreciative which had been achieved. The first solemn use work on this technology occurred during the First World War. By the year 1917, French co-workers and P.Langevin started to perfect an ultrasonic maritime detectors.

The transducer used at this point was a mixture of thin quartz crystals joined between two by glue between two plates. The transducer was also astride housing appropriate for submission. After the end of the World War 1, the brothers didn't realize their aim of emanating a high frequency inside the water and determining the depth by analysis the echo of the sent signal. The intentional significance of their accomplishment was not ignored by any industrialized nation since that period the improvement of sonar transducers, systems, materials, and the circuit has certainly not stopped (Pallikarakis 2010, p. 444).  

During 1920-1940, the achievement of sonar inspired strong improvement on the activity of different types of piezoelectric components for non-resonating and echoing. Some of the kinds of this action are; megacycle quartz resonator which was made to act as stabilizer of frequency for the vacuum-tube oscillator, leading to a ten-fold escalation in stability. There was also new varieties of transient pressure recording were started allowing the study of internal combustion engines and explosive together with a host of other previous unmeasurable vibration (Tandeske 2008, p. 335).

From 1940-1965, is a period known as Second Generation Application with Piezoelectric Ceramics in the history of the development of the piezoelectric. This was a period of the Second World War, during this period the US, the Soviet Union, and Japan lonely research groups according to the developed capacitor material revealed that some ceramic materials displayed dielectric constant 100 times higher than usual cut crystals. During this development, the device was done together with the piezo material progress specific industries. Due to some rules, the companies communicate on what was transpiring. This was because the amended materials were made during time of war in research situations, so the skilled workers were forced to work in a classified atmosphere (Tandeske 2008, p. 412).

From 1965-1980 is a period known as Japanese Development. Early 1965 Japanese marketable initiatives started to earn the benefits of the stable use and material progress work which commenced with a prosperous fish finder test. Starting from an global business outlook, they were known as carrying the ball. For example creating new knowledge, new use, new processes and the new commercial market area in a comprehensible way and lucrative way, were some of the strategies used. Persevered determinations in materials exploration had generated new piezoelectric families who were economical to Vernitrion’s PZT, but free of obvious constraint. With the materials obtainable, Japanese developers rapidly developed many kinds of piezoceramic signal filter, which elaborated necessities in radio, communication equipment, and piezoceramic igniters for natural gas and television (Webster 2003, p. 356).

 From 1980-present, this can also reorganize as "search for the high volume market." The viable achievement of the Japanese determinations has enticed the attention of the industry of several nations and encouraged a new determination to advance effective piezoceramic materials. Solid state motion currently the single most vital frontline, the technical goal of the confines are to attain suitable and sensibly priced actuators which are low in power and consumption and high consistency and environmental roughness, the hunt for an impeccable piezo product chances is now in process. Judging from the growth in worldwide action and from faced in the last quarter of the 20^th C, significant economic and technical improvement appear sure.  

How it work:

This sensor operates by conversion mechanical and electrical energy forms. Whenever a polarized crystal is subjected to pressure, some mechanical deformation occurs in the polarized crystal this result to the generation of the electric charge. The creation of the mechanical deformation or electric charge will be then recorded using a piezo sensor. The working of the sensor can be well understood through three different modes;  

Transverse effect: Here a force along a neutral y-axis is applied to create charges along the x-axis, and it must be perpendicular to the line of force.  The quantity of the charge on x-axis depends on the geometric dimension of the relevant piezoelectric element, and the charge will be;

Longitudinal effect: The quantity of charge generated is relative to the force applied but not dependent of the element shape and size of the piezoelectric. Placing some elements electrically in parallel and mechanically in series is the only method to escalate the output and the output charge will be; 

Shear effect: The charges generated are purely proportionate to the applied force and  does not dependent on the element shape and. Placing n elements electrically in parallel and mechanically in series, the charge will be given by;

Whenever the diaphragm senses pressure, it will push the shaft down which pressurizes the crystal, and the voltage is produced as indicated in the figure below (Tandeske 2008, p. 345). And the piezoelectric will appears as in the figure below.

                                           

How they are made:

In the pressure sensor, a tinny membrane and a colossal base are applied; the pressure applied loads the elements in a specific direction. A seismic mass is devoted to the crystal elements, for accelerometers.  Whenever the accelerometer experience any motion the invariant seismic mass will load the elements obeying newton’s law  (F=ma). A thin membrane will transfer the force to the element for the pressure sensor, and on the accelerometer, there should be an attached seismic mass which applies the force. The sensor many at times will have a high sensitivity than one physical quantity (Uchino 2009, p. 321). The pressure sensor will indicate an incorrect signal when they are open to pulsations. Erudite pressure sensor thus uses acceleration recompense element in totalling to the pressure detecting elements. By cautiously corresponding those elements, the signal acceleration will be deducted from the joint pressure signal and the acceleration to come up with real information on pressure. The pulsation of sensors can yield unused energy from mechanical pulsations; this will be archived through using a piezoelectric material to convert mechanical strains into usable electric energy. The graph below indicates the piezoelectric sensor frequency response

                                           

Whenever the diaphragm senses pressure, it will push the shaft down which pressurizes the crystal, and the voltage is produced.

Some of the common piezoelectric which is used more often than not include the following;

• Rochelle salt
• Lithium Sulphate
• Polarized barium titanate
• Quartz
• Ammonium dihydrogen

This technology has been applied to check the pressure magnitude and fluctuation which is very vital is fields like blood flow and also in the respiratory body. This sensor creates electric al potential in response to an applied pressure is of growing interest. For this sensor when pressure, acceleration, or force is supplied to a quartz crystal, change is created across the crystal which is proportional to that force applied (Tandeske 2008, p. 477).

The following are some of the advantages of piezoelectric pressure sensor;

• The piezoelectric sensor has a very high-frequency response; this makes it operate effectively.
• It is very simple to use since it has small dimension and large measuring range ( it is user-friendly).
• It is a self-generating hence no need of an external source of power.
• Quartz and Barium titanate can be made in any shape and size desired, it also has a wide range of dielectric current.

Some of the disadvantages of the piezoelectric include;

• The sensor is not suitable to be used for measurement in a static condition.
• This device requires a great impedance cable for electrical interfere since the device works on very minor electric.
• The yield of the device may differ according to the temperature disparity of the crystals.

Bibliography:

Beeby, S 2004, MEMS Mechanical Sensors, Artech House, Hull.

Bhat, S 2013, Piezoelectric sensor for foot pressure measurement, 2nd edn, University of Wisconsin--Madison, Beijing.

G, J 2003, The Measurement, Instrumentation, and Sensors, 4th edn, Springer Science & Business Media, Belgate.

Gao, W 2010, Precision Nanometrology: Sensors and Measuring Systems for Nanomanufacturing, 3rd edn, Springer Science & Business Media, Chicago.

Gaura, E 2011, Smart Mems and Sensor Systems, 3rd edn, Imperial College Press, Manchester.

Gautschi, G 2013, Piezoelectric Sensorics: Force Strain Pressure Acceleration and Acoustic Emission Sensors Materials and Amplifiers, 5th edn, Springer Science & Business Media, Hull.

Gregory K. McMillan 2003, Process/Industrial Instruments and Controls Handbook, 5th edn, McGraw Hill Professional, Whasington Dc.

Iniewski, K 2012, Optical, Acoustic, Magnetic, and Mechanical Sensor Technologies, 3rd edn, CRC Press, Amsterdam.

John P. Dakin 2006, Handbook of Optoelectronics, 4th edn, CRC Press, Washington.

Pallikarakis, N 2010, XII Mediterranean Conference on Medical and Biological Engineering and Computing, 4th edn, Springer Science & Business Media, New York.

Staff, MI 2011, World Transducer-Sensor Technology Assessment, 3rd edn, Frost & Sullivan Market Intelligence, New Jasrsey.

Tandeske, D 2008, Pressure Sensors: Selection and Application, 3rd edn, CRC Press, Chicago.

Uchino, K 2009, Ferroelectric Devices, 4th edn, CRC Press, New York.

Vetelino, J 2010, Introduction to Sensors, 3rd edn, CRC Press, New York.

Vijaya, MS 2016, Piezoelectric Materials and Devices: Applications in Engineering and Medical Sciences, 1st edn, CRC Press, London.

Webster, JG 2003, Electrical Measurement, Signal Processing, and Displays, 1st edn, CRC Press, Washingto DC.