Staff directory Peng Xiao



  • Optomechanical crystals for spatial sensing of submicron sized particles

    Navarro-Urrios D., Kang E., Xiao P., Colombano M.F., Arregui G., Graczykowski B., Capuj N.E., Sledzinska M., Sotomayor-Torres C.M., Fytas G. Scientific Reports; 11 (1, 7829) 2021. 10.1038/s41598-021-87558-4. IF: 4.379

    Optomechanical crystal cavities (OMC) have rich perspectives for detecting and indirectly analysing biological particles, such as proteins, bacteria and viruses. In this work we demonstrate the working principle of OMCs operating under ambient conditions as a sensor of submicrometer particles by optically monitoring the frequency shift of thermally activated mechanical modes. The resonator has been specifically designed so that the cavity region supports a particular family of low modal-volume mechanical modes, commonly known as -pinch modes-. These involve the oscillation of only a couple of adjacent cavity cells that are relatively insensitive to perturbations in other parts of the resonator. The eigenfrequency of these modes decreases as the deformation is localized closer to the centre of the resonator. Thus, by identifying specific modes that undergo a frequency shift that amply exceeds the mechanical linewidth, it is possible to infer if there are particles deposited on the resonator, how many are there and their approximate position within the cavity region. OMCs have rich perspectives for detecting and indirectly analysing biological particles, such as proteins, viruses and bacteria. © 2021, The Author(s).

  • Reversing the Humidity Response of MoS2- And WS2-Based Sensors Using Transition-Metal Salts

    Xiao P., Mencarelli D., Chavez-Angel E., Joseph C.H., Cataldo A., Pierantoni L., Sotomayor Torres C.M., Sledzinska M. ACS Applied Materials and Interfaces; 13 (19): 23201 - 23209. 2021. 10.1021/acsami.1c03691. IF: 9.229

    Two-dimensional materials, such as transition-metal dichalcogenides (TMDs), are attractive candidates for sensing applications due to their high surface-to-volume ratio, chemically active edges, and good electrical properties. However, their electrical response to humidity is still under debate and experimental reports remain inconclusive. For instance, in different studies, the impedance of MoS2-based sensors has been found to either decrease or increase with increasing humidity, compromising the use of MoS2 for humidity sensing. In this work, we focus on understanding the interaction between water and TMDs. We fabricated and studied humidity sensors based on MoS2 and WS2 coated with copper chloride and silver nitrate. The devices exhibited high chemical stability and excellent humidity sensing performance in relative humidity between 4 and 80%, with response and recovery times of 2 and 40 s, respectively. We have systematically investigated the humidity response of the materials as a function of the type and amount of induced metal salt and observed the reverse action of sensing mechanisms. This phenomenon is explained based on a detailed structural analysis of the samples considering the Grotthuss mechanism in the presence of charge trapping, which was represented by an appropriate lumped-element model. Our findings open up a possibility to tune the electrical response in a facile manner and without compromising the high performance of the sensor. They offer an insight into the time-dependent performance and aging of the TMD-based sensing devices. © 2021 American Chemical Society.


  • Fracturing of Polycrystalline MoS2 Nanofilms

    Marianna Sledzinska, Gil Jumbert, Marcel Placidi, Alois Arrighi, Peng Xiao, Francesc Alzina, Clivia M. Sotomayor Torres Acs Applied Electronic Materials. 2 (4): 1169-1175; 2 (4): 1169 - 1175. 2020. 10.1021/acsaelm.0c00189. IF: 0.000