Thermal energy conversion by coupled shape memory and piezoelectric effects

• Published in: Journal of micromechanics and microengineering Vol. 22; no. 9; pp. 94005 - 7
• Main Authors: Zakharov, Dmitry, Lebedev, Gor, Cugat, Orphee, Delamare, Jerome, Viala, Bernard, Lafont, Thomas, Gimeno, Leticia, Shelyakov, Alexander
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.09.2012
• Subjects: Cooling; Harvesters; Joining; Lead zirconate titanates; Piezoelectricity; Prototypes; Shape memory alloys; Thermal energy
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/22/9/094005

This work gives experimental evidence of a promising method of thermal-to-electric energy conversion by coupling shape memory effect (SME) and direct piezoelectric effect (DPE) for harvesting quasi-static ambient temperature variations. Two original prototypes of thermal energy harvesters have been fabricated and tested experimentally. The first is a hybrid laminated composite consisting of TiNiCu shape memory alloy (SMA) and macro fiber composite piezoelectric. This composite comprises 0.1 cm3 of active materials and harvests 75 µJ of energy for each temperature variation of 60 °C. The second prototype is a SME DPE 'machine' which uses the thermally induced linear strains of the SMA to bend a bulk PZT ceramic plate through a specially designed mechanical structure. The SME DPE 'machine' with 0.2 cm3 of active material harvests 90 µJ over a temperature increase of 35 °C (60 µJ when cooling). In contrast to pyroelectric materials, such harvesters are also compatible with both small and slow temperature variations.