Highly Sensitive Flexible Poly(dimethylsiloxane) Composite Sensors Based on Flame-Synthesized Carbon Foam Made of Vertical Carbon Nanosheet Arrays

A simple approach for the flame synthesis of carbon foam (FCF) via one-step catalytic deposition of carbon on a Ni template was developed. FCF was deposited within 5 min at ∼500 °C in an alcohol flame and the foam strut wall was found to be actually made of vertical carbon nanosheets. The carbon strut layer displayed a distinctive morphology between its two surface sides. The rough inner surface of the carbon strut originated from the vertically aligned carbon sheets, while some short carbon nanotubes with a length less than 1 μm grew on the outer strut surface. The strain sensitivity of the FCF@poly(dimethylsiloxane) composite was investigated, including the dynamic electrical response. It was believed that the unique hierarchical structure of the carbon foam promoted the performance of the composite sensors, which exhibited one of the highest strain sensitivity among the carbon foam-based strain sensors. At 30% stretching strain, the resistance of the composite increased remarkably more than 700%. Moreover, the sensor exhibited high and stable sensitivity in various physiological detection, including the finger bending and wrist pulse. The present flame synthesis method could be a facile and an effective technique to deposit a vertical carbon nanosheet array, which could find many promising applications, including human physiology monitoring and medical detection.