Timely detection of breast cancer not only positively influences patient treatment and life quality, but also possesses far-reaching implications for public health and medical research. And miRNAs, as emerging breast cancer-related biomarkers, demonstrate heightened sensitivity to disease progression. In this study, the same precursor was utilized to prepare micromaterials with large and small cavities, this was the safeguard for sensing probes and signals. And the signal amplification process was accomplished with strand displacement assistance by target excitation. Encouragingly, it was successfully and accurately detected miRNA-21 and miRNA-155 within 10 fmol/L - 10 nmol/L. Due to the unique sensing design, the signal can be read out not only by small fluorescent devices, but also by portable glucometers. The biosensor features several excellent working performances and illuminates resource-poor areas by equipping the most common glucometers. So, it is a sensitive, portable and promising biosensor.