Cervical spondylosis is a common disease that is often caused by long-term abnormal cervical curvature due to activities such as reading books and using computers or smartphones. This paper explores building an untethered and skin-integrated device in an e-skin form factor to monitor and haptically correct neck posture. The proposed design features a multilayered structure that integrates all flexible electronic circuits and components into a compact skin space while being untethered and skin conformal. An accelerometer in the e-skin attaches to the neck for posture sensing, while four vibration actuators closely touch the neck skin to provide localized vibrotactile stimuli that encode four-direction correction cues of neck flexion and lateral bending . To ensure the reliability of posture sensing and vibrotactile rendering during neck movement, it is necessary to prevent the e-skin device from shifting position. Thus, a hollow structure-based method is implemented for stably attaching the e-skin to the neck skin. Experiments validated the e-skin device's sensing precision, skin-conformal compliance, stickiness, stability and effectiveness during the motion of neck postures, including its discrimination of localized four-direction vibrotactile cues. A user study verified the device's performance for sensing and correcting different abnormal neck postures during activities such as using smartphones, reading books, and processing computer files. The proposed e-skin device may create opportunities for more convenient cervical spondylosis prevention and rehabilitation.