246. Is This Device Safe to Use Near My Programmable Shunt Valve? Evaluation of Smartphone Magnetometers in Detection of Unsafe Devices

Authors: Smruti K. Patel, MD; Smruti Patel, MD; Jorge Fernandez, MD; Carlie McCoy; Jesse Skoch, MD (Cincinnati, OH)


Electromagnetic fields(EMFs) produced by many “smart” devices can often be a concern for parents of children with shunted hydrocephalus harboring programmable valves(PVs). Due to lack of data regarding EMF strengths of these devices, it is generally recommended to limit their use in close vicinity to a PV. The aim of this study was to evaluate the EMFs of commonly used devices using a smartphone magnetometer in determining safety near a programmable shunt.


A total of five mobile phones(iPhone X,iPhone 7,Sony Xperia,Samsung Galaxy S9,and Xiaomi Mi A1) were used to measure the magnetic properties of various devices. The calibrated magnetometer on the multi-platform smartphone app Phyphox was used to measure the EMF of each device at the source and at two inches away from the source. Measurements were obtained in microTesla and Gauss. 


We found that among the smartphones used for measurement, the values obtained by each magnetometer was comparable across all devices and in the range of manufacturer published values. Each device reaches a threshold between 40 and 50 Gauss at which point the magnetometer value saturates and stops providing information beyond this field strength.


A growing body of literature regarding various magnetic devices reports the potential risks of inadvertent shunt valve resistance changes.  An expanding abundance of consumer grade technology is available that produces EMFs and could come in proximity to a PV by either design or accident.  While some PVs are extremely resistant to strong EMF noise, many sensitive valves are still in use today.  Rather than limit patients with an over-cautious ban on all devices with EMFs, we submit that self-screening with a very cautious 40 Gauss threshold using any smartphone could allow for safe use of select technologies without waiting for third-party reports to be generated.