All-Printed MXene–Graphene Nanosheet-Based Bimodal Sensors for Simultaneous Strain and Temperature Sensing

Multifunctional sensors with integrated multiple sensing capabilities have enormous potential for in situ sensing, structural health monitoring, and wearable applications. However, the fabrication of multimodal sensors typically involves complex processing steps, which limit the choices of materials and device form factors. Here, an aerosol jet printed flexible bimodal sensor is demonstrated by using graphene and Ti3C2Tx MXene nanoinks. The sensor can detect strain by measuring a change in the AC resistive voltage while simultaneously monitoring temperature by detecting the DC Seebeck voltage across the same printed device pattern. The printed bimodal sensor not only expands the sensing capability beyond conventional single-modality sensors but also provides improved spatial resolution utilizing the microscale printed patterns. The printed temperature sensor shows a competitive thermopower output of 53.6 μV/°C with ultrahigh accuracy and stability during both steady-state and transient thermal cycling tests. The printed sensor also demonstrates excellent flexibility with negligible degradations after 1000 bending cycles. The aerosol jet printing and integration of nanomaterials open many opportunities to design and manufacture multifunctional devices for a broad range of applications.