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# Detection of biological signals from a live mammalian muscle using an early stage diamond quantum sensor

Paper Title:

### Detection of biological signals from a live mammalian muscle using an early stage diamond quantum sensor

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##### Journal
NatureView Original

### Abstract

Jargon-minimized Summary: A room-temperature biosensor based on the quantum mechanical property of Nitrogen-Vacancy(NV) centers in diamond was used to detect the action potential(AP) signal from mice' hind limb muscles. Specifically, ion flows associated AP signal generates weak current and produces magnetic field, which were detected by the NV centers. Since the experiment was carried out in an unshielded environment, the authors further explored de-noise solutions that could remove background and obtained AP magnetic signal that correlates well with simultaneous probe electrophysiology measurement. Optimistically, the authors believe that this is a step towards non-invasive mapping of the brain neuron signal using diamond quantum sensor. Original Summary: The ability to perform noninvasive and non-contact measurements of electric signals produced by action potentials is essential in biomedicine. A key method to do this is to remotely sense signals by the magnetic field they induce. Existing methods for magnetic field sensing of mammalian tissue, used in techniques such as magnetoencephalography of the brain, require cryogenically cooled superconducting detectors. These have many disadvantages in terms of high cost, flexibility and limited portability as well as poor spatial and temporal resolution. In this work we demonstrate an alternative technique for detecting magnetic fields generated by the current from action potentials in living tissue using nitrogen vacancy centres in diamond. With 50 pT/$$\sqrt{\text {Hz}}$$sensitivity, we show the first measurements of magnetic sensing from mammalian tissue with a diamond sensor using mouse muscle optogenetically activated with blue light. We show these proof of principle measurements can be performed in an ordinary, unshielded lab environment and that the signal can be easily recovered by digital signal processing techniques. Although as yet uncompetitive with probe electrophysiology in terms of sensitivity, we demonstrate the feasibility of sensing action potentials via magnetic field in mammals using a diamond quantum sensor, as a step towards microscopic imaging of electrical activity in a biological sample using nitrogen vacancy centres in diamond.

### Discussion5

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