TY  - JOUR
A1  - Assagra, Yuri A.O.
A1  - Altafim, Ruy Alberto Pisani
A1  - do Carmo, Joao P.
A1  - Altafim, Ruy A.C.
A1  - Rychkov, Dmitry
A1  - Wirges, Werner
A1  - Gerhard, Reimund
T1  - A new route to piezo-polymer transducers: 3D printing of polypropylene ferroelectrets
JF  - IEEE transactions on dielectrics and electrical insulation
N2  - Here, a promising approach for producing piezo-polymer transducers in a one-step process is presented. Using 3D-printing technology and polypropylene (PP) filaments, we are able to print a two-layered film structure with regular cavities of precisely controlled size and shape. It is found that the 3D-printed samples exhibit piezoelectric coefficients up to 200 pC/N, similar to those of other PP ferroelectrets, and their temporal and thermal behavior is in good agreement with those known of PP ferroelectrets. The piezoelectric response strongly decreases for applied pressures above 20 kPa, as the pressure in the air-filled cavities strongly influences the overall elastic modulus of ferroelectrets.
KW  - 3D printing
KW  - polymer ferroelectrets
KW  - sensors and actuators
KW  - piezoelectrets
KW  - electret polymers
KW  - soft electro-active materials
KW  - functional materials
KW  - soft matter
Y1  - 2020
U6  - https://doi.org/10.1109/TDEI.2020.008461
SN  - 1070-9878
SN  - 1558-4135
VL  - 27
IS  - 5
SP  - 1668
EP  - 1674
PB  - Inst. of Electr. and Electronics Engineers
CY  - Piscataway
ER  - 
TY  - JOUR
A1  - Altafim, Ruy Alberto Pisani
A1  - Basso, Heitor Cury
A1  - Altafim, Ruy Alberto Pisani
A1  - Lima, L.
A1  - de Aquino, C. V.
A1  - Goncalves Neto, Luiz
A1  - Gerhard, Reimund
T1  - Piezoelectrets from thermo-formed bubble structures of fluoropolymer-electret films
N2  - The acetone extracts of the root bark and stem bark of Erythrina sacleuxii showed antiplasmodial activities against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the acetone extract of the root bark afforded a new isoflavone, 7-hydroxy-4 -methoxy-3'- prenylisoflavone (trivial name 5-deoxy-3' - prenylbiochanin A) along with known isoflavonoids as the antiplasmodial principles. Flavonoids and isoflavonoids isolated from the stem bark of E. sucleuxii were also tested and showed antiplasmodial activities. The structures were determined on the basis of spectroscopic evidence.
Y1  - 2006
UR  - http://ieeexplore.ieee.org/servlet/opac?punumber=94
U6  - https://doi.org/10.1109/TDEI.2006.247822
SN  - 1070-9878
ER  - 
TY  - JOUR
A1  - Basso, Heitor Cury
A1  - Aquino, C. V.
A1  - Altafim, Ruy Alberto Pisani
A1  - Altafim, Ruy Alberto Pisani
A1  - Gerhard, Reimund
T1  - Piezoelectricity of a single bubble formed by two oppositely charged Teflon-FEP films
Y1  - 2006
SN  - 1-4244-0547-5
ER  -