Pb(Zr₀.₅₂Ti₀.₄₈)O₃ (PZT) thin films are of interest for their large dielectric permittivity, ferroelectric, and piezoelectric properties. The material has been widely studied for use in high frequency transducers, multi-layered capacitors, and ferroelectric random access memory. Copper foils are an inexpensive, flexible substrate with a low resistivity which makes them ideal for many transducer and capacitor applications. PZT thin films on copper foils were produced by RF sputtering and crystallized under reducing conditions. Causes and prevention of a cuprous oxide interlayer are discussed. The film structure was characterized by XRD, SEM, and AFM. The permittivity was low, but remanent polarization increased to as high as ~40 μC/cm² as film thickness and crystallization temperature increased. Residual stresses were measured by x-ray diffraction using the sin²ψ method. The relative permittivity of the PZT/Cu films was measured as a function of applied AC electric field. By performing a Rayleigh analysis on this data one can determine the relative contributions of the intrinsic, reversible, and irreversible components to the permittivity. The residual stress could be correlated to the reversible part of the permittivity. The first order reversal curves (FORCs), which characterize the ferroelectric switching, give indications of the defect state of the film. Cantilever energy harvesters were fabricated. Large electrodes were able to be evaporated onto the films after oxidizing pinholes and cracks on a hot plate. Devices were tested on a shaker table at < 100 Hz. A dynamic model based on Euler-Bernoulli beam equations was used to predict power output of the fabricated devices. The observed output was comparable to model predictions. Resonant frequency calculations were in line with observed first and second resonances at ~17 Hz and ~35 Hz which were also close to those predicted by the dynamic model. / Graduation date: 2013

Projektet beskriver ett tillvägagångssätt för att alstra energi genom solceller och piezoelektronik. Ett kretskortsbaserat system designades som utnyttjade superkondensatorer som lagringsenhet. Planen var att integrera systemet i en sko. Genom denna teknik kan man då substituera eller minimera batteriladdningen för smarta enheter eller mindre anordningar. Det önskvärda resultatet med projektet var att se om det gick att koppla detta system till en mikrokontroller som kunde drivas på låg spänning. Rapporten fick ett positivt resultat med en konstant utspänning på 1.8 volt som kunde driva en mikrokontroller. Dock tog det lång tid för superkondensatorerna att laddas upp på grund av den impedans som fanns i systemet. Aktiviteter som utnyttjar detta system kommer att påverka uppladdningens resultat. Detta gör kretsen optimal för aktiviteter som involverar rörelse och sol, såsom hiking. / The past couple of decades gave rise to smartphones, smart watches, and smart homes. Now researchers are looking for ways to make smart clothing. One use case of smart clothing is smart shoes which can give some very useful sensed information especially in the sports industry and healthcare. Such sensed data include temperature, distance and calories, fall detection and many more. This application scenario can be designed to be battery free if we make use of the human motion and solar power. Many research papers exist which present how to exploit swing and shock excitations from the shoes to harvest energy. In this project this energy combined with solar energy will be used to power a low driven MCU. I design a pcb which include solar panels and piezoelectric modules to store the energy in supercapacitors. The goal is to integrate this pcb in a shoe, meaning that it has to have a small size and low power. The results of the project showed that a constant voltage at 1.8 volt could be achieved however recharge time is a factor to take into consideration. The system showed positive results for activities including movements and sun such as hiking.