This paper proposes a novel flexible pressure sensor based on carbon black (CB), carboxy-methyl cellulose (CMC), and gelatin. CMC and gelatin are both food-grade materials that are degradable, non-toxic, and environmentally friendly. Freeze drying is performed to obtain a sensor porous honeycomb structure that achieves not only a wide monitoring range from 0 to 140% strain, but also high sensitivity (maximum gauge factor of 12.5, which is higher than ordinary conductive CB composite systems). After 3000 repeated presses, the sensor remains unchanged and retains its high sensitivity. This stable sensor response is promising for long-term practical applications. The proposed sensor is applied to a speech recognition system and can distinguish the different components of a sentence, thereby achieving accurate speech recognition. It is also capable of monitoring human body movements, including joint flexion and finger movement. Finally, a sensor integrated network is constructed for application to a human-machine interface. The proposed CB sponge pressure sensor has important applications for medical wearable devices and smart wear.