Optimization and modeling of sensor systems based on ntc thick film segmented nickel manganese thermistors

[S. O. Aleksić]

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Apstrakt: Doktorska disertacija ima za temu tri vrste senzorskih sistema formiranih od NTC termistora (debeloslojnog tipa). Termistori kao senzorske komponete su primenjeni za različita merenja: 1. temperature sloja zemljišta po dubini, 2. protoka vode i 3. vektora brzine vetra. Termistorske paste su razvijene od prahova NiMn2O4 (nikl manganit) i praha Cu0,2Ni0,5Zn1,0Mn1,3O4 (modifikovani prah) uz dodatak organskog nosioca prahova i vezivnog stakla. Debeloslojni termistori imaju složenu planarnu višećelijsku strukturu redno-paralelnog (segmentiranog) tipa, koja je optimizovana za praćenje promena i prenosa toplote u ispitivanim radnim sredinama (fluidima ili zemlji). Analiza električnih pojava na debeloslojnim segmentiranim termistorima koji se samozagrevaju vršena je za različite uslove protoka fluda. Temperatura zemljišta (obradivog sloja) po dubini merena je svakodnevno u više tačaka za jednogodišnji ciklus. Električni odziv na realizovanim prototipovima senzorskih sistemima sa debeloslojnim NTC termistorima je meren a potom i analiziran kao funkcija promene parametara ambijenta: određen je radni opseg, osetljivost i na kraju je procenjena nesigurnost merenja. Sva pomenuta istraživanja i analize električnih pojava na debeloslojnim termistorima i senzorskim sistemima su vršena u cilju modelovanja odziva i određivanja opsega primene. Pri tome su korišćeni fizički zakoni koji opisuju rad termistora, a izvedene su i odgovarajuće relacije matematičko-fizičkog tipa. Primena prototipova (senzorskih sistema) opisanih u ovoj disertaciji očekuje se u industriji, poljoprivredi i meteorologiji.

Abstract : The topic of this dissertation are three kinds of sensor systems made of NTC thermistors (thick film type). The thermistors as sensor components were applied for different measurements: 1 ground temperature profile, 2. flow rate (liquids), and 3. wind velocity. Thermistors pastes are developed using the initial nickel manganese NiMn2O4 and modified nickel manganese Cu0,2Ni0,5Zn1,0Mn1,3O4 powders, organic vehicle and glass frits. Thick film thermistors have a complex planar cell-based structure of serial / parallel (segmented) type, which is optimized for monitoring a heat change and transfer in the operating media (fluids or ground). Analysis of electrical phenomena in thick film self-heating thermistors was done at different fluid flow regime. Analysis of ground temperature profile was based on daily temperature measurements at different depth points of the arable ground top layer during whole year cycle. The electrical responses on realized prototypes of sensor systems based on the NTC thermistors (thick films) were measured and initially analysed as a function of a few ambient parameters which affect the application range, sensitivity and inaccuracy of measurements. All mentioned experiments and analyses of electrical phenomena in the thick film thermistors and sensor systems were done with intention of modeling of the responses and defining of the application range. The physical laws which describe the thermistor operation were used and appropriate mathematical-physical equations were derived. The application of the described prototypes (sеnsor systems) in this dissertation is expected in industry, agriculture and meteorology.

debeloslojni NTC termistori, temperaturni profil tla, senzor protoka vode, senzor brzine vetra.

thick film NTC thermistors, ground temperature profile, water flow rate sensor, wind sensor.

536.587:620.172.21(043.3)

Elektrotehnika

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