Towards a magnetoresistive platform for neural signal recording

Abstract

A promising strategy to get deeper insight on brain functionalities relies on the investigation of neural activities at the cellular and sub-cellular level. In this framework, methods for recording neuron electrical activity have gained interest over the years. Main technological challenges are associated to finding highly sensitive detection schemes, providing considerable spatial and temporal resolution. Moreover, the possibility to perform non-invasive assays would constitute a noteworthy benefit. In this work, we present a magnetoresistive platform for the detection of the action potential propagation in neural cells. Such platform allows, in perspective, the in vitro recording of neural signals arising from single neurons, neural networks and brain slices.

Advances in Magnetoresistive Biosensors

“…Although their approach was interesting, the neural response recorded is still obscure. At about the same time, a similar platform for in vitro magnetic neural recording from an array of 12 MTJs, each of 3 × 40 μm 2 , was reported by Sharma et al [141]. According to their report, for a bias field of 6 mT for noise measurements, the integrated noise observed was at 250 nT (RMS) for a frequency range of 1 Hz to 1kHz.…”

“…Since the permeability of the biological tissues is like the permeability of free space, the magnetic field recordings from the brain have high spatial as well as temporal resolution. In this respect, linear MR sensors [138][139][140][141][142] have been investigated for neural signal recording.…”

“…Although Amaral et al's [138] work with GMR as a neural recording probe in an in vitro set-up showed promising results, it lacks any experimental corroboration from other existing techniques of recording a neural response, e.g., LFP recording or patch-clamp recording. Sharma et al's [141] work on in vitro magnetic recording using MTJ sensor array is also promising but their experiments lack an adequate number of repeats and controls. Despite attempts to study the in vivo magnetic responses of SV-GMR sensors, the reports published require further validation.…”

“…The signal (in mV) and the resistance (in Ω) are the local field potential (LFP) recordings and MTJ signal response, respectively. The shape of both the signal resembles each other[141]; (b) in vivo experimental set-up to record neural response from rat cerebral cortex[140]; (c) Four TMR sensors arranged in Wheatstone Bridge configuration along with neural response as recorded by the sensor configuration (in pT)[142]. (a) Reprinted under a Creative Commons Attribution (CC BY) license.…”

Biocompatibility of a Magnetic Tunnel Junction Sensor Array for the Detection of Neuronal Signals in Culture

“…Due to the long-term biocompatibility requirements and the high sensitivity of cultured neurons to toxic elements (in particular metals) that can be released by the devices immersed in a saline solution, no attempts have been carried out so far for primary neuronal cultures. Recent studies assessing the capability of these magnetoresistive sensors in detecting a magnetic field of biological origin at the local scale (Barbieri et al, 2016; Caruso et al, 2017) concern macroscopic in vitro and in vivo systems, such as muscle or visual cortex, except for Sharma et al (2017b), in which very preliminary results on cell viability were shown for neurons cultured for 2 weeks on magnetic tunneling junctions (MTJ) protected by 170 nm of capping layers.…”