The new technologies of piezoceramic sensors synthesis

Transcription

1 ISSN 9-4 ULTRAGARSAS (ULTRASOUND), Vol. 66, No., 0. The new tehnologies of piezoermi sensors synthesis V.M. Shrpov, A.Vldišusks,.A. Molhnov, Zh.V. Sotul Cherksy Stte Tehnologil University, 460, Shevhenko lvd., Cherksy, Ukrine, -mil: Kuns University of Tehnology, Studentu56-50, LT-544 Kuns, Lithuni AMAC Teh. In. North Wles, A, USA Astrt The new tehnologies of synthesis of piezoermi sensors re desried in rtile. or the first time design of piezoeletri trnsduers nd sensors onsider reltive position of vetors of the polristion op in piezoelement fore nd vetor of n eletri field (sptil energy fore piezoelement struture). Besides, the rrngement of eletrodes on piezoelement surfe lso leds to hnge of dynmi hrteristis of the sensor. The tehnology on the sis of sptil eletromehnil feedk llows to rete sensors with the redued error nd expnded ndwidth. Inlusion of piezoelement sheme of the eletri filters llows it to get sensors with filter dynmi hrteristis. As the piezoelement usully represents n eletromehnil osilltory system, joining it to mehnil or eletri elements hnges its hrteristis. Inrese of the level of n output signl nd expnsion of working frequenies rnge n e rehed y using the exittion signl of the piezoelement in the form of mender. Keywords: piezoeletri trnsduer, sptil eletromehnil, feedk. Introdution iezoeletri trnsduers nd sensors re widely pplied in hydrooustis, eletrooustis, ultrsoni, medil, mesuring tehnis, in snning proe mirosopy, piezoengines nd in other res of siene nd engineering [, ]. iezoeletri trnsduers oupy speil ple in hydrooustis, eing in essene, the ers nd eyes of underwter nd surfe ships. As it is known, trnsduer is devie whih trnsforms one of energy to nother type of energy. or exmple, therml energy - in to eletri, fore - in to displement, pressure - in to eletri voltge or urrent, eletri voltge of one level - in t eletri voltge of nother level et. []. The sensor is trnsduer tht trnsforms physil quntity, s rule, in n eletri signl (voltge, urrent, frequeny, phse, et.) [, 4]. In other words, the sensor is trnsduer for reeption of the mesuring informtion. In the given work these terms re used s equivlent. or designing of piezoermi sensors usully piezoelement of ertin form nd size, from definite piezoermi mteril with ertin eletrophysil properties re used. Usully vetor of the fore operting on piezoelement (pressure, et.) is prllel polristion vetor. Simultneously the vetor of the fore is prllel to the vetor of eletri field Е, of reting the output signl, tht is perpendiulr to the eletrodes whih re put on piezoelement surfe (ig. ) [, 4, 5]. These eletrodes re used for piezoelement polristion t mnufturing. Simultneously they re used lso for piking up of useful signl pused y fore, pressure, elertion, et., nd lso for pplition in piezoelement of n eletri voltge to use of the piezoelement s trnsmitter. These types of sensors re well known [, 4, 5]. In this se using ertin piezoelement it is possile to develop only one sensor with ertin hrteristis. or retion of the sensor with other hrteristis erlier it ws neessry to use other types of piezoelements, of different dimension, shpe or other piezomterils. ig.. Type of sptil energy fore struture of piezoelement: а - onventionl; - trnsverse; - domin-dissiptive Results ' а. Sptil energy fore struture of piezoermi elements In work [] it ws proposed to tke into onsidertion reltive position of vetors, Р nd for sensor design. This rrngement of vetors hs een nmed y sptil energy fore struture of piezoermi elements (SS). '

2 ISSN 9-4 ULTRAGARSAS (ULTRASOUND), Vol. 66, No., 0. Let us onsider piezoelement in the shpe of retngulr prllelepiped (ig. ). letrodes re put on ll sides of prllelepiped nd re not onneted mong themselves, nd the piezoelement is polrised etween plnes - /. The mesured fore is direted in prllel to the vetor of polristion (perpendiulrly to the plne ), nd the output voltge ts etween the surfes - '. Thus, for the given sensor ll three vetors re prllel to the xis Z ( ) (ig. а). As we lredy mrked, it is known (trditionl) se of n rrngement of vetors,, (sptil energy fore struture). The piezoelement, in whih fore the vetor is perpendiulr to the vetor, is less often used. These types of the sensors hve een nmed trnsverse [4, 5]. the following ftors n influene their hrteristis [4, 5]: energy dispersion on domins; hnge of the eletri pity etween eletrodes; ourrene in piezoelement of other types of osilltions. Definition of the possile ontriution of eh listed ftors demnds further study. Shemes of trnsduers presented in ig., do not show possile versions of their exeution. In totl, for one piezoelement in the shpe of retngulr prllelepiped it is possile to otin 7 (!) different versions of trnsduers with vrious hrteristis [5]. In ig. experimentl mplitude-frequeny responses (АR) of trnsduers represented in ig. re shown. These trnsduers were mde of piezoelement with dimensions mm from the piezoermi ЦТС-9 (nlogue ZT-5A). The mesurements of AR were performed in piezotrnsformer mode y mens of the frequeny response nlyzer AR Х-46 nd photogrphing of hrteristis ws mde y the digitl mer «Nikon- D90». Trnsient responses of the trnsduers re shown in ig.. ig.. Amplitude-frequeny responses of the trnsduers shown in: а ig. а; - ig. ; - ig. Another type of the sensor is in whih the output signl is piked-up y the eletrodes - / (ig. ). In this se vetor the is perpendiulr to the vetor. This type of the sensor hs een nmed domin-dissiptive [,, 6]. The physis of the proesses ourring in these trnsduers, is studied insuffiiently. It is supposed, tht ig.. Trnsient responses of the trnsduers whih re shown in: ig. а; - ig. ; - ig. 4

3 ISSN 9-4 ULTRAGARSAS (ULTRASOUND), Vol. 66, No., 0. Aording to ig. nd, there is hnge of reltive positions of vetors, nd. Therefore, dynmi hrteristis of trnsduers essentilly hnge. This irumstne opens vrious opportunities t designing of sensors [,, 7].. Sptil rrngement nd onnetion of piezoelement eletrodes Chnge of output signl eletri field vetor Е position n e relize y division of piezoelement eletrodes into prts nd onnetion of these prt so tht the ngle α etween the vetor Е nd the polriztion vetor Р is 0<α<90 o ig. 4. Trditionl piezoelement with divided eletrodes It is known tht piezoelement with two or more eletrodes is lled piezotrnsformer [4]. If the piezoelement eletrodes re divided two equl prts the sensor hrge sensitivity will derese twie, euse the hrge is proportionl to the eletrodes re. The voltge sensitivity remins the sme s for the piezoelement with undivided eletrodes. It is quite ovious, tht the pity etween the eletrodes -' (or '-) will e less, thn the pity etween the eletrodes -' ( - '). Therefore it is possile to otin the eletri voltge severl times more thn on the eletrodes -' or -' [4, 7]. The piezosensor voltge sensitivity will inrese even more, if eletrodes nd re shifted from eh other (for wht it is possile to divide initil eletrodes into three prts (ig. 5). / ' ig. 5. iezoelement with system of three eletrodes It is neessry to notie, tht the sptil rrngement of eletrodes nd their onnetion results not only in hnge of eletrodes pity nd sensitivity, ut lso is hnge of dynmi hrteristis (AR, pulse nd trnsient responses). Sensors n e mde from piezoelements in the shpe of disks or hollow ylinders with eletrodes in the form of semi-disks, disks nd rings [4, 7]. / ' /. Sptil eletromehnil feedk It is known tht the feedk llows to hnge essentil hrteristis of utomti ontrol systems (input nd output resistne, time onstnt, dynmi hrteristis et.). The feedk is lso widely used in the mesuring tehni []. or exmple, the positive feedk llows to exite resonnt osilltions in piezosensors nd to uild on this sis sensors of vrious physil dimensions []. A negtive feedk in resonnt piezotrnsduers gives the hne to linerize them grdution hrteristis []. The feedk possesses unique properties nd llows to improve prmetres of mesuring devies essentilly. In kind of tht piezosensors output size ( hrge or voltge) depends not only from mehnil influene (fore, pressure, elertion, tht is diret piezoeffet), ut lso of eletri voltge (the return piezoeffet), ws offered to enter feedk into the uxiliry hnnel whih ws reted y mens of dditionl system of eletrodes or the dditionl piezoelement whih hd with the ore plnr or oplnr. The sheme of one of mny versions piezoermi sensor with feedk, implementing the offered method, is shown in ig. 6 [, 4]. This sensor represents the losed stti utomti system []. It onsists of the piezoelement nd voltge mplifier A. Three eletrodes, nd re put on piezoelement. The eletrode is onneted to the input of the voltge mplifier, the eletrode - to the generl wire of the iruit nd the eletrode - n dditionl eletrode on the piezoelement - to the output the voltge mplifier. U ig. 6. The piezoermi sensor with feedk U OUT The eletrodes re pled on vrious sides of piezoelement, therefore the feedk in this se is lled sptil. The trnsfer funtion of suh devie is given y WTR WB = W, + WTR β () were W (р) is the trnsfer funtion of the iruit of the diret trnsformtion; W TR (р) is the trnsfer funtion of the iruit of diret trnsformtion with feedk; β(р) is the trnsfer funtion of the feedk iruit. Reltive error γ B of the devie, presented in ig. 6, it is possile to define y []: γ B = γ W γ W ( ), () + W β + W β were γ W is the reltive error of iruit of the diret trnsformtion with feedk. A 5

4 ISSN 9-4 ULTRAGARSAS (ULTRASOUND), Vol. 66, No., 0. rom this expression it is esy to see ondition t whih the error of the piezosensor with feedk will e equl to zero, γ B = 0: W β = () The sensitivity of the sensor t W β = will derese twie. It is neessry to note tht, in this se vrious rrngement of vetors,, IN, Е B llows to with piezoelement in the shpe of prllelepiped, to otin tens versions of sensors with vrious hrteristis. 4. Inlusion of piezoelements in eletri filters The ide is sed on development of suh piezoelements whih fter inlusion in the eletri filter possess the mplitude-frequeny responses (АR) whih will orrespond to the АR of the filter [4, 9]. letri filters re well enough studied nd desried in [6-8]. As the eletri filter is lled the devie serving for pssing (or suppression) of eletri voltge or urrents of different frequenies. Depending on hrteristis, some filters whih re of the gretest interest for the given se, re y low-pss nd high-pss filters frequenies re known. Low-pss filters (L) pss flututions of ll frequenies from diret urrent nd to some ut-off frequeny ω t. High-pss filters (H) pss osilltions from some ut-off frequeny ω to infinitely high. Two versions of the sensor with piezoelements in L nd H re shown in ig. 7 [7]. in shemes of the sensors piezotrnsformers, tht is piezoelements with two systems of eletrodes. Besides, it is proposed to hve eletrodes on piezoelement so tht the eletri field vetor etween these eletrodes ws under n ngle α to the polristion vetor (0<α 90 ). It llows to otin n eletri voltge whih exeeds the voltge for onventionl se when on these eletrodes α=0 [4]. Two shemes of the sensors relising these ides re shown in ig. 8 [4, 9]. R 5 R 4 5 R 4 R ig. 8. Sensors with piezotrnsformers in eletri filters: а - in L; - in H R R4 U out U out ig. 7. Sensors with piezoelements in shemes of eletri filters: а - in L; - in H Drwk of these sensors is neessity to use in some iruits two piezoelements or piezoelement nd pitor. To eliminte this drwk, it is offered to use R R 5. Tehnology of dditionl elements The essene of this tehnology onsists in ddition to piezoelement of elements whih hnge sensor hrteristis. Here two ses re possile, t lest. In the first se the seond piezoelement, metl plte or the ultrsoni onentrtor mehnilly is joined to piezoelement [, 4]. In the seond se the pity joins piezoelement eletril indutne, n osilltory ontour, piezoelement or piezoelement prt [, 7]. Two piezoelements onneted mong themselves mehnilly nd eletrilly (symmetri imorph piezoelement), llow to inrese sensitivity 0-0 times nd t the sme time to redue resonnt frequeny. Connetion of piezoelement nd metl plte (symmetri imorph piezoelement) lso leds to inrese of sensitivity 0 times to nd redution of the resonnt frequeny. In imorph piezoelements rise flexurl osilltions tht llows to use them in miroeletromehnil systems nd devies (ММS), for exmple, in snners of nnomirosopes [0-]. Joining of the ultrsoni onentrtor to piezoelement [4] inreses mplitude of the osilltory displement (or prtile veloity), tht llows to use suh devies for ultrsoni utting, wshing, dispersion of liquids, nd lso in mesuring devies on the sis of 6

5 ISSN 9-4 ULTRAGARSAS (ULTRASOUND), Vol. 66, No., 0. resonnt piezoelements []. The use of onentrtors for inrese of performne of low-frequeny ultrsoni rditors is lso promising. Beuse the piezoelement is the eletromehnil devie whih my e represented y n equivlent iruit (in speifi se - resonnt iruit), onnetion to it of eletri elements (resistors, pitne, indutne) n hnge hrteristis of piezosensors. or exmple, onnetion of resistor in series with piezoelement, redues qulity of piezoelement nd expnds ndwidth of the trnsduer []. Inlusion f the pitor etween the input nd the output systems of eletrodes of piezotrnsformers type sensor lso llows to expnd working rnge of frequenies [4]. Indutne onnetion etween eletrodes of the piezotrnsformer type sensor llows to inrese level of the output voltge nd ousti power, to expnd ndwidth of the sensor, et. Investigtion results in this re will e pulished in seprte work. 6. Tehnology of synthesis of the trnsduers, onsidering eletri signls Chnge eletri signl form pplied to the trnsduer, n led to hnge of its hrteristis. or exmple, if to put on the eletro-ousti trnsduer eletri voltge in the form of mender, АR of suh trnsduer extends towrds low frequenies []. Applying to piezoelement simultneously two eletri signls new properties nd trnsduer funtions n e otined. or exmple, if to put on piezoelement with two inputs two signls of the sinusoidl shpe with frequenies lose to its resonnt frequeny powerful lowfrequeny signl my e otined [4]. 7. The omined tehnology In this se the tehnologies desried ove re used simultneously or in vrious omintions. It is esy to see, tht in this se from one piezoelement hundreds of versions of sensors with vrious hrteristis, mong whih it is possile to get the sensor with neessry or est hrteristis (inrese of ury, stility, sensitivity, expnsion of working rnge of frequenies, et.) n e otined. Conlusions Tehnologies of synthesis of piezoeletri trnsduers, exploiting sptil energy fore struture, sptil eletromehnil feedk, sptil rrngement nd swithing of eletrodes of piezoelement, tehnology of inlusion piezoeletri virtors nd piezotrnsformers into eletri filters, tehnology of joining to piezoelement of dditionl elements nd others re developed. By results of this work out 400 ptents of the USSR, the Russin edertion nd Ukrine hve een otined. Referenes. Shrpov V. M., Musienko M.., Shrpov. V. iezoeletri sensors. d. V.M. Shrpov. Mosow: Tehnospher (in Russin).. Shrpov V. iezoermi sensors. NY: Springer, Sensors. d. Shrpov V. nd olishuk. Cherkssy: Brm (in Russin). 4. riden J. Modern sensors. The diretory. Mosow: Tehnospher (in Russin). 5. iezoermi trnsformers nd sensors. Shrpov V., Мinev I., Sotul Zh., Bzilo К., Kunitsky L. d. Shrpov V. Cherkssy: Vertil (in Russin). 6. Shrpov V., Vldisusks A., Bzilo K., Kunitsky L., Sotul Zh. Methods of synthesis of piezoermi trnsduers: sptil energy fore struture of piezoelemеnt. ISSN 9-4 Ultrsound Vol.64. No Jonson D., Jonson D., Мur G. The diretory on tive filters. М.: nergotomizdt (in Russin). 8. Тitse У., Shenk К. Semi-ondutor iruitry. М.: Мir. 98 (in Russin). 9. Каufmn М., Sidmn А. rtil guidne y lultions of shemes in eletronis. The diretory in t. Т. : d..n. okrovskiy (in Russin). 0. Shrpov V., Kzys R., Vldisusks A., Kunitsky L., Sotul Zh., Тuz V., Bzilo K. Trnsduers with piezoelements in shemes of eletri filters. ISSN 9-4 Ultrsound. 00. Vol. 65. No Mironov V. L. undmentls of snning proe mirosopy. Mosow: Tehnosfer (in Russin).. Shrpov V., Vldisusks, ilimonov S. Bimorph ylindril piezoermi snner for snning proe nnomirosopes. ISSN 9-4 Ultrsound Vol. 64. No Shrpov V., Vldisusks, ilimonov S. iezoermi snners on the sis of plnr imorph piezoelements for snning proe nnomirokopes. ISSN 9-4 Ultrsound. 00. Vol. 65. No Shrpov V., Мusiyenko M., Sotul Zh, Kunitsky L. Aout the effet of expnsion of reprodued frequeny nd y еletroousti trnsduer. ISSN 9-4 Ultrsound Vol. 64. No V. M. Shrpov, A. Vldišusks,. A. Molhnov, Zh. V. Sotul Nujos pjezokerminių jutiklių sintezės tehnologijos Reziumė Sukurtosios jutiklių sintezės tehnologijos leidži keisti jutiklių erdvinį elektromehninį grįžtmąjį ryšį ir tip pkeisti jutiklių dro džnines hrkteristiks. Tm tikslui nudojms pjezoelements su dug elektrodų, ki kurie iš jų jungimi į stiprintuvų grįžtmąjį ryšį r yr du pjezoelementi, kurių viens jungims į elektrinės shemos grįžtmąjį ryšį. teikt spudi