Triboelectrification is a process of charge separation and transfer between tow materials through mechanical contact and friction. [9] The electrical output performance of TENG can be improved by enhancing the surface roughness of the triboelectric materials, which can lead to an enlargement of the contact or friction area. [10] Hence, a lot of investigations focus on developing the protruding surface structures, including the dome array, [2b] cube array, [11] pyramid array, [12] nanorod array, [13] and subwavelength architectures, [14] in order to enhance the output electricity. However, the above structures have some limitations including complex, long-time, high-cost fabrication processes based on photolithography, electrochemical deposition, or soft lithography methods. [9a,14-15] Trinh and Chung [9a] proposed a microneedle array (MA)-based TENG and its novel mechanism of mixed bending-friction-deformation behavior for increasing the output performance. The MA-based TENG exhibited extremely high output power.The key component of MA-based TENG is a bendable MA. Various techniques have been developed to fabricate MA. Typically, MA can be fabricated by the subtractive processes, in which the 3D structures of MA are selectively carved out of a 2D substrate, including lithography with wet or dry etching, [16] laser cutting, [17] micromachining, [18] and wireelectrode cutting. [19] The limitations of these subtractive processes are complex, expensive, time consuming, or not suitable for mass production. Additive processes, such as 3D printing, [20] droplet-born air blowing, [21] electro-drawing lithography, [22] thermal drawing lithography, [23] and magnetorheological drawing lithography, [24] also can form 3D structures of polymer MA from droplets or 2D surfaces. 3D printing is a flexible process that allows personalized customization, but it is not suitable for mass production. The other processes suffer from the limitations of difficult operation and relatively low production efficiency. [22a,25] The micromolding technique is a near-net-shape forming process, which has been employed to fabricate polymer microneedles owing to its potential for mass production. [9a,26] However, it is characterized by multiple costly and time-consuming steps, such as master preparation, mold fabrication, polymer filling, and microneedles separation. [22a,27] Furthermore, Since the invention of triboelectric nanogenerator (TENG) in 2012, it has become one of the most important innovations in energy conversion technologies. A flexible microneedle array (MA)-based TENG is proposed using the closed bending-friction-deformation behavior of MA for the mechanical energy harvest. A novel magnetization-induced self-assembling method is introduced to efficiently fabricate the bendable MA for the TENG. The 3D structures of MA are continuously self-assembled from a moving film of curable magnetorheological fluid under the assistance of a rotating external magnetic field. The mass production of MA may be achieved using this method ...