We present the optical realization and characterization of complex suspended microchannel resonator (SMR) for biomechanical sensing applications. We exploit the flexibility of two-photon direct laser writing to optimize a highly versatile fabrication strategy based on a shell-writing procedure with the aim to reduce fabrication time of big inlet/outlet sections compatible with most microfluidic systems for lab-on-chip. Compared with standard microfabrication techniques, requiring several technological steps to obtain suspended hollow structures, this method allows to fabricate complex SMR sensors in only one fabrication step by virtue of its intrinsically 3-D nature. The realized resonant structure was characterized by laser doppler vibrometry, showing good agreement with finite-element methods simulations and an experimental quality factor of the fundamental mode of ~60.