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The StatIQ Band samples voltage at 1200 Hz. Therefore, the onboard microcontroller can detect the rate of change of body voltage with great accuracy. This allows for an ESD detection algorithm that identifies rapid voltage changes that occur from a grounding event well below what is felt as an electrostatic shock. It is these low voltage ESD events that are most concerning in an ESD environment, as they go unnoticed and can cause latent damage to electronics.

There are two scenarios in which the relationship between E-field and body voltage breaks down. If the user is naturally charged and stands close to a grounded object, the charge distribution on the body will be asymmetric and the voltage measurement from the StatIQ Band will be slightly higher or lower than the actual voltage. However, the polarity is always correct, and zero charge means zero voltage. Second, if the user stands near a charged insulator, the charged object will induce a charge on the body even if it is grounded, and the StatIQ Band will detect this. Just remember that a non-zero voltage measurement from the StatIQ Band always indicates the presence of charge on the user, which should be considered an ESD concern.

We sell a SB200 version of the StatIQ Band, which does not contain any radios, making it appropriate for use in secure locations. Settings on the device can be changed from a computer with a connection via the USB-C cable.

The StatIQ band’s sensor is an electric field mill, the smallest and most accurate of its kind, which allows it to be packaged in a wearable device. The principles of electrostatics dictate that the electric field on the surface of a conductor is proportional to the underlying charge density. Therefore, the E-field measurement is always a measure of charge on the arm, whether generated by the user or from induced charge effects (by standing next to a charged object).

The localized charge on insulating fabrics near the StatIQ Band creates false readings when the local E-field measurement is translated to body voltage. Example: The user might be at 100V body voltage, but wearing a polyester shirt, the StatIQ Band measures 1000V because of the local charge near the Band. Also, ESD event detection is suppressed, because charge stays on the insulating shirt even if there is a grounding event on the body. We haven't exhaustively tested all fabrics, but have found that pure cotton clothing gives accurate results to within 100V because it doesn't hold a lot of local charge compared to nylon or polyester.

By definition, voltage is measured relative to a point of reference (it is a difference in potential). Electrostatic charge, however, is an absolute quantity that doesn’t require a reference. The StatIQ Band measures the local charge on the arm of the user. This charge is extrapolated to the total charge on the body, then divided by the body’s self-capacitance to determine voltage. This conversion is valid in the absence of nearby charged objects.

The zero disc corrects for the minimal drift that the sensor may experience. It creates a complete faraday cage around the electric field mill, providing an accurate zero reference. If there is a consistent offset in your environment that remains after zero’ing the StatIQ Band with the zero disc, it is also possible to remove this offset by zero’ing from the mobile apps. Be careful with this function because it may mask the actual presence of charge in your environment.

The onboard LiPo battery provides up to 20 hours of run time. It may be recharged in 1 hour via the USB-C cable, much like your cell phone.

StatIQ Band measurements have been meticulously compared to body voltage measurements from industry standard charge plate monitors. Except under certain circumstances, these measurements agree to within 10% for a wide range of body geometries. The StatIQ Band's sensor has <10V equivalent RMS noise, and <20V drift per day (drift can be corrected by zero'ing the device with the included zero disc).

The reference for the field mill measurement is really the user’s body. The StatIQ Band measures the electric field coming off the body that results when static charge is present. This relationship holds whether or not the body is electrically connected to Earth ground.