Historically, contact electrification (CE) was humanity's first and only source of electricity up until around the 18th century, yet its true nature is still elusive. Today it is considered a core component of technologies such as laser printers, LCD production processes, electrostatic painting, and separation of plastics for recycling as well as a major industrial hazard (damage to electronic systems, explosions in coal mines, fires in chemical plants, etc.) due to electrostatic discharges (ESD) accompanying CE. In a vacuum, ESDs of a simple adhesive tape are so powerful that they generate enough X-rays to take an X-ray image of a finger.
