Stretchable Magnetoelectronics

Research on non-rigid electronics started almost 20 years ago originally motivated by an interest in flexible, paper-like displays [Gus92, Rog01]. There are several ways to achieve non-rigid electronics [Kim10-1]. One is related to the development of organic electronics [Sek10], which is flexible but slow. A good alternative to this approach are stretchable inorganic electronics, which combine advantages of being flexible with the speed and performance of conventional semiconductor-based electronics [Cav10]. Since being first introduced, stretchable electronics have become a dynamically developing research area which is of strong application interest due to the possibility to reshape the functional element on demand after its fabrication (Figure 1). There are already a variety of stretchable devices commercially available, i.e. electronic displays [Rog01, Chu09] and integrated circuitry [Kel04] to name a few. Until recently, the main focus was on fabrication of stretchable high-speed electronics [Kim11] and optoelectronics [Kim10] (Figure 1). However, the family of shapeable electronics is not limited to these two members. Only very recently, we reported for the first time the fabrication of stretchable magnetoelectronics [Mel11, Mel12, Mel12-1]. These stretchable magnetoelectronics pave the way towards the development of a unique class of devices with important functionality being not only stretchable and fast, but also with the ability to react and respond to a magnetic field.

Figure 1: Family of shapeable electronics: (Top panel) Opto-electronics [Kim10]: array of light emitting diodes (LEDs). (Bottom left) Electronics [Kim11]: Multifunctional inflatable balloon catheters. (Bottom right) New member of the family - shapeable magneto-electronics: a giant magneto-resistive (GMR) sensor element on a free-standing rubber membrane. The shapeability of the magnetic sensor element is due to the wrinkle formation. The figure is taken from [Mel11].

Layered magnetic structures revealing a giant magnetoresistance (GMR) effect are crucial components of highly sensitive magnetic sensor devices. We fabricated [Co/Cu] and [Py/Cu] GMR multilayers [Mel11, Mel12] as well as spin valve systems [Mel12-1] on free-standing elastic Poly(dimethylsiloxane) (PDMS) membranes. The GMR performance of GMR sensors on rigid silicon and on free-standing PDMS is similar and does not change with tensile deformations of up to 29% revealing a top sensitivity of 0.8 %/Oe in the magnetic field of 12 Oe [Mel12-1]. These highly stretchable and highly sensitive elements responding to a magnetic field are demanded for novel application fields like smart skin, flexible and stretchable consumer electronics equipped with magnetic functionalities.

References:

[Gus92] G. Gustafsson et al., Nature 357, 477 (1992).
[Rog01] J. A. Rogers et al., PNAS 98, 4835 (2001).
[Kim10-1] D. H. Kim et al., Adv. Mater. 22, 2108 (2010).
[Sek10] T. Sekitani et al., Adv. Mater. 22, 2228 (2010).
[Cav10] F. Cavallo et al., Soft Matter 6, 439 (2010).
[Chu09] I. J. Chung et al., Molecular Crystals and Liquid Crystals 507, 1 (2009).
[Kel04] T. W. Kelley et al., Chemistry of Materials 16, 4413 (2004).
[Kim10] R. H. Kim et al., Nature Mater. 9, 929 (2010).
[Kim11] D. H. Kim et al., Nature Mater. 10, 316 (2011).
[Mel11] M. Melzer et al., Nano Letters 11, 2522 (2011).
[Mel12] M. Melzer et al., RSC Adv. 2, 2284 (2012).
[Mel12-1] M. Melzer et al., Adv. Mater. 24, 6468 (2012).