Abstract
Flexible microphone and earphone prototypes for wearable applications were developed by using ElectroMechanical Film (EMFiℳ)*. A suitable application for the developed headset can be, for instance, as accessory of rescue services or sport enthusiasts. Due its versatile properties, EMFi can be used both as microphone and earphone material. The sensor operation is based on thickness changes caused by an external force or pressure, generating charge and thus voltage on the electrodes. EMFi also works conversely, converting electrical energy to vibration and hence functioning as an actuator. In addition, measurement electronics for the microphone and earphone were implemented. Preliminary test measurements were carried out: the frequency response of the EMFi microphone was compared with the one of a reference B&K microphone. The EMFi microphone provides rather good response. Also subjective listening tests were done. For these measurements, the EMFi headset was integrated inside a neoprene hood used by the surface rescuers. Both with the microphone and earphone the quality of voice was sufficient. Based on the results, EMFi seems to be a promising material for some wearable audio applications.
Keywords
EMFi is a registered trademark of Emfit Ltd.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
M. Paajanen, J. Lekkala and K. Kirjavainen, ElectroMechanical Film (EMFi) — a New Multipurpose Electret Material, Sensors and Actuators A: Physical, 84 (2000), pp. 95–102, 2000.
Encyclopedia Britannica, http://www.britannica.com.
Homepage of Emfit Ltd, http://www.emfit.com.
M. Paajanen, J. Lekkala and H. Välimäki, Electromechanical modeling and properties of the electret film EMFi, IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 8, No. 4, pp. 629–636, 2001.
K. Kirjavainen, Electromechanical Film and procedure for manufacturing same, U.S. Patent No. 4654546, 1987.
J. Backman and M. Karjalainen, Audio and ultrasonic transducers based on Electrothermomechanical Film (ETMF), Acoustics, Speech, and Signal Processing International Conference on 3–6 Apr. 1990, 1173–1776.
G. Evreinov and R. Raisamo, One-directional position-sensitive force transducer based on EMFi, Sensors and Actuators A: Physical, 123–124 (2005), pp. 204–209.
M. Antila, H. Nykänen and K. Saarinen, Multichannel Electromechanical Film panel loudspeakers, AES 16th International Conference on Spatial Sound Reproduction, 1999.
H. Nykanen, M. Antila, J. Kataja, J. Lekkala, and S. Uosukainen, Active control of sound based on utilizing EMFi technology, ACTIVE 99, pp. 1159–1170.
Homepage of Screentec Ltd, http://www.screentec.com.
Homepage of B-Band Ltd, http://www.b-band.com.
T. Koivistoinen, S. Junnila, A. Varri and T. Koobi, A new method for measuring the ballistocardiogram using EMFi sensors in a normal chair, Engineering in Medicine and Biology Society, 2004. pp. 2026–2029.
H. Young and R. Freedman, University Physics, 9th edition, Addison-Wesley Publishing Company, Ch. 21, pp. 646–668.
M. Paajanen, H. Välimäki and J. Lekkala, Modelling the Electromechanical Film (EMFi), Journal of Electrostatics, 48 (2000), 193–204.
J. Lekkala, M. Paajanen and K. Kirjavainen, A New dimension in loudspeakers, Materials World, 2001, 22–24.
Genelec 1029A Active monitoring system datasheet, www.genelec.com.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2007 International Federation for Medical and Biological Engineering
About this paper
Cite this paper
Kärki, S., Salpavaara, T., Lekkala, J. (2007). EMFi in wearable audio applications. In: Leonhardt, S., Falck, T., Mähönen, P. (eds) 4th International Workshop on Wearable and Implantable Body Sensor Networks (BSN 2007). IFMBE Proceedings, vol 13. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-70994-7_15
Download citation
DOI: https://doi.org/10.1007/978-3-540-70994-7_15
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-70993-0
Online ISBN: 978-3-540-70994-7
eBook Packages: EngineeringEngineering (R0)