Novel magnetic stimulation methodology for low-current implantable medical devices. (November 2019)

• Record Type: Journal Article
• Authors: Bernardo, Rodrigo; Rodrigues, André; Soares dos Santos, Marco P.; Carneiro, Pedro; Lopes, António; Sequeira Amaral, João; Sequeira Amaral, Vítor; Morais, Raul
• Is Part Of: Medical engineering & physics. Volume 73(2019)
• Page Start: 77
• Page End: 84
• Publication Date: 2019-11
• Subjects: Medical device -- Biomagnetic device -- Implantable device -- Magnetic stimulation -- Magnetic field; Biomedical engineering -- Periodicals; Biomedical Engineering -- Periodicals; Physics -- Periodicals; Génie biomédical -- Périodiques; Biomedical engineering; Electronic journals; Periodicals; 610.28
• DOI: 10.1016/j.medengphy.2019.07.015
• Languages: English
• ISSNs: 1350-4533

Abstract

Highlights: Current micro-scale biomagnetic devices require very high electric current excitations. A novel biomagnetic methodology requiring up to 50-fold lower currents is proposed. Osteogenic stimuli (0.1–7 mT) is achieved by low current excitations (0.06–4.3 mA). Device designs with heights lower than 1 mm are able to deliver effective stimuli. Stimuli heterogeneity can be defined by core diameters and stimulators positioning. Abstract: Recent studies highlight the ability of inductive architectures to deliver therapeutic magnetic stimuli to target tissues and to be embedded into small-scale intracorporeal medical devices. However, to date, current micro-scale biomagnetic devices require very high electric current excitations (usually exceeding 1 A) to ensure the delivery of efficient magnetic flux densities. This is a critical problem as advanced implantable devices demand self-powering, stand-alone and long-term operation. This work provides, for the first time, a novel small-scale magnetic stimulation system that requires up to 50-fold lower electric current excitations than required by relevant biomagnetic technology recently proposed. Computational models were developed to analyse the magnetic stimuli distributions and densities delivered to cellular tissues during in vitro experiments, such that the feasibility of this novel stimulator can be firstly evaluated on cell culture tests. The results demonstrate that this new stimulative technology is able to deliver osteogenic stimuli (0.1–7 mT range) by current excitations in the 0.06–4.3 mA range. Moreover, it allows coil designs with heights lower than 1 mm without significant loss of magnetic stimuli capability. Finally, suitable core diameters and stimulator-stimulator distances allow to define heterogeneity or quasi -homogeneity stimuli distributions. These results support the design of high-sophisticated biomagnetic devices for a wide range of therapeutic applications.