## 1 Introduction  
The fabrication of low electrical percolation threshold polymer nanocomposites aims to reduce the weight fraction of electrically conductive nanomaterial necessary to achieve a given level of electrical resistivity of the nanocomposite [1]. There are several strategies to achieve a lower electrical percolation threshold in nanocomposites [2]. Most methods consist of aligning the conductive nanoparticles [3] or constraining the location of carbon nanotubes (CNTs), such as the utilisation of polymer beads during in situ polymerization, forcing the contact between CNTs [4] or the migration to the interface of immiscible polymers [5]. Concerning nanocomposites with aligned nanoparticles, [PERSON] et al. [6] demonstrated that mechanical deformation induced a decrease in nanoparticle contacts, thus decreasing the electrical conductivity of the composite. The use of immiscible polymers to force the nanoparticle's location at the interface does not allow the control of their position within the nanocomposite. Conversely, magnetic forces may induce the contact between conductive nanoparticles with a ferromagnetic response, making it possible to control their location in the polymer matrix, thus allowing the fabrication of conductive patterns that can be used as sensor electrodes.  
The magnetic field can be generated using electromagnets or permanent magnets. During the fabrication process, the strong magnetic field can lead to coil overheating problems that may damage the electromagnets [7], thus making the use of permanent magnets more attractive. The latter is more straightforward to use, but the magnetic field density can be lower. The effective use of lower magnetic fields may be possible by functionalising CNTs with magnetic nanoparticles or using metal plating techniques, as reported by [PERSON] et al. [8]. Several metal plating methodologies were investigated in their work, including nickel, cobalt, and nickel-iron plating. Still, this is an unnecessary extra step when the MWCNTs can already provide a magnetic response.  
The magnetic response of CNTs has been interpreted using different theories. [PERSON] et al. [9] interpret it as resulting from the movement of the electrons circling the circumference of the CNTs producing a significant orbital magnetic moment, explaining the anisotropic susceptibility. Other theories are related to vacancies in the CNT structure that induce ferromagnetic behaviour [10]. CNTs produced by the Catalytic Chemical Vapor Deposition (CCVD) method present significant contamination by the catalyst materials used in their fabrication process, which are typically encapsulated in the CNTs, and will undoubtedly be the primary source of their magnetic response [11].  
The precise control of the location of the MWCNTs in the polymer matrix may lower the electrical percolation threshold and help sensor fabrication. This technique can be used for the application of piezoresistive sensors [12], triboelectric sensors and generators [13; 14; 15], capacitive sensors [16], temperature sensors [17], heating bands [18], etc. The present work explores the use of permanent magnets to fabricate low electrical percolation threshold samples by controlling the position of the MWCNTs inside PDMS. The nanocomposites were tested for application as triboelectric and piezoresistive sensors to detect physical contact and mechanical deformation. In the future, this fabrication technique can produce multisensory devices in the same substrate, which may be applicable in soft robotics and wearables [19].