The given master thesis deals with polypyrrole (PPy) filled porous silicon (pSi) as a potential candidate for novel electrochemically controlled actuators and sensors. One part is to investigate the response of the atomic lattice of the pSi matrix on the electrochemical actuation of PPy. The characterisation of the lattice parameter is done in-situ at beamline P08, PETRA III, DESY. An electrochemical cell is designed allowing for the simultaneous measurement of the diffraction signal during the electroactuation. During the electrochemical actuation charge is consumed irreversibly. The irreversible behaviour can be observed in the strain of the lattice, too. The mechanical characterisation is achieved by utilizing laser excited ultrasonic guided waves. The setup used for this was built by RECENDT GmbH. Initially, it could be used to quantify the elasticity of isotropic materials. It was commissioned and extended in the previous project work to extend the usability to the characterisation of anisotropic materials like crystalline pSi. The results of the mechanical characterisation are compared to anodic aluminium oxide (AAO) as a similar but simpler porous material. For AAO a small deviation from perfect isotropy is obtained. pSi’s behaviour is much more complex. Anisotropy, caused by the crystalline matrix, induces changes in dispersion relations measured in different propagation directions. Furthermore, additional complexity is introduced by the pores and their shape. The measured dispersions cannot be described by one effective medium as the density increases with the depth of the pores. pSi is synthesized by electrochemical etching of monocrystalline silicon. Empty membranes and epi-layers are functionalized with PPy by electropolymerization. The porosities and filling fractions of the samples are characterized by sorption isotherms.