Another classic e-textile prototype, a coil pattern made of conductive silver paste, is screen printed on paper mulberry sheet. Firstly a sound source signal from an amplifier is sent into the coil to generate magnetic field. These magnetic fields are combined with the paper placed behind the paper mulberry paper. The strong magnetic resonance transmits the vibrations into the air, and these air vibrations are transmitted to the eardrum, and a simple paper mulberry finger speaker is completed. There are many conditions that determine the quality of the speaker, such as the strength of the magnetic field. Basically, if the lower the impedance of the conductive silver paste, the more turn of the coil, the wider width of the coil line, indicating that more current can be passed through the coil, therefore the stronger magnetic field it is. In addition, the flexibility and elasticity of the substrate for the conductive coils also determine the quality of the resonance. For example, too thick cotton cloth is not suitable for the substrate to generate vibration. Generally, the resonance of synthetic fiber cloth will be the best option, such as the fabric for umbrella.