Thanks to the rapid development of wireless sensor networks and ultra-low-power electronic technology, the demand for long survival times of electronic components is becoming more and more urgent. Harvesting energy from the surrounding environment is highlighted as the alternative way of powering small electronic devices, especially for those placed in irreplaceable and inaccessible places. Conversion of mechanical energy into electrical energy using piezoelectric materials has been a promising solution to solve these problems among these potential solutions, called Piezoelectric Energy Harvesting (PEH). A typical piezoelectric energy harvester is composed of three parts: a main mechanical structure that works under the excitation of external vibrations, an electrical interface circuit that converts the generated AC voltage to DC voltage for the needs of most electronic devices, and an energy storage device that stores electrical energy for intermittent use. The configuration of a rectangular piezoelectric cantilever for vibrational energy harvesting has been well studied in various literature, including modeling, design, and parameter optimization of the cantilever-type piezoelectric harvester. For best performance, the piezoelectric energy harvester should be mostly excited around its resonant frequency; deviation from its resonant frequency would cause a significant reduction in the output voltage. However, practical environmental vibrations are mostly random and uncertain, i.e. broadband and multidirectional. These problems have been addressed recently in some aspects. The first approach consists in tuning the resonance frequency of the vibration-capturing structure, thus adapting it to the excitation of the external vibration; the second is to expand the bandwidth... to the middle of the paper... including the scalable standard interface for M-PEH, the scalable Series-SSHI interface for M-PEH and the scalable SECE interface for M-PEH . The operating principles and technical characteristics of these scalable collection interfaces for M-PEH are demonstrated. Furthermore, the harvested power of these scalable harvesting interfaces for M-PEH is calculated in theory and validated in experiments. The rest of the document is structured as follows. In Section 2, the basics of piezoelectric harvester modeling are first reviewed, and then three scalable harvesting interfaces for M-PEH are proposed. In Section 3, the theoretical analysis and harvested power expressions of these three interfaces for M-PEH are derived. A detailed description of the experimental setup and results is provided in Section 4. In Section 5, some concluding remarks and future work are discussed.