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MAY 2025 I PCB007 MAGAZINE 33 were trained to wear gowns before entering the air lock and then follow decontamination pro- cedures before entering the cleanroom. Our investigation revealed that unauthorized per- sonnel ignored these procedures because they didn't want to take the time to do things prop- erly. It took around 30 minutes for the clean- room to return to its rated particle count when- ever someone opened the door without the proper precautions. Maintaining a Class 10,000 rating was difficult when the door constantly opened and closed throughout the day. Written procedures are worthless if not followed. To keep defects to a minimum, management must provide leadership. However, those run- ning the various processes must also buy into the effort. I've been in far too many shops where a single process engineer tries to con- trol every process in the plant with minimally paid operators running the equipment, whose only goal is to put in their eight hours and go home. Without the operators' cooperation, any attempt to reduce defects and increase yields is doomed to failure. PCB007 Don Ball is a process engineer at Chemcut. To read past columns or to contact Ball, click here. The likelihood of two human fingerprints being identi- cal is extremely low—about 1 in 640 billion. Even identi- cal twins, despite sharing the same genetic information, have unique fingerprints. A new technology now allows us to engrave these unique fingerprint patterns onto electronic skin, with the probability of matching an arti- ficial fingerprint being 10²³² times lower than that of hu- man fingerprints. A research team, led by Professor Kyoseung Sim from the Department of Chemistry at UNIST has developed advanced electronic skin that features unique wrinkling patterns, surpassing even those of human fingerprints. This innovation may pave the way for a new era in which physical AI robots can possess unique fingerprint identi- fication capabilities. To be effective, electron- ic skin must incorporate sen- sors for tactile sensation while also maintaining flexibility. Thus, flexible organic materi- als are more suitable than rig- id inorganic ones. Moreover, electronic skin meant for fin- gers must be capable of dis- tinguishing between objects, making it challenging to create skin that possesses both func- tionality and unique finger- print-like patterns. Professor Sim's team has Study Unveils Groundbreaking Fingerprint-enabled Electronic Skin With Enhanced Security designed a method to easily engrave random wrinkling patterns on styrene–ethylene–butylene–styrene (SEBS) electronic skin. The technique involves chemically treat- ing a flexible polymer to initially create the skin and then applying toluene solvent before spinning it rapidly. As the toluene evaporates, the skin's surface contracts to form these random wrinkles. The probability of this artificial fingerprint being repro- duced in the exact same shape is merely 10 -43 based on a 1mm² area—an astounding figure that is 10²³² times lower than the probability for human fingerprints. When scaled up to the size of a human fingerprint, the likelihood of producing the same pattern approaches zero. Addition- ally, this electronic skin is resilient to physical impacts, heat, and humidity, allowing for the preservation of its fin- gerprint-like structure. When implanted into a robotic hand, the developed electronic skin enables the robot to grasp objects similarly to humans, rec- ognize surface textures, and dif- ferentiate between living be- ings. The research team has demonstrated a physical inter- action where a robot equipped with temperature-sensing elec- tronic skin avoids hot objects, mimicking human responses. (Source: UNIST)