Brain diseases affect millions of people and have a huge social and economic impact.The use of neural probes for studies in animals has been the main approach to increasing knowledge about neural network functioning.Ultimately,neuroscientists are trying to develop new and more effective therapeutic approaches to treating neurological disorders.The implementation of neural probes with multifunctionalities(electrical,optical,and fluidic interactions)has been increasing in the last few years,leading to the creation of devices with high temporal and spatial resolution.Increasing the applicability of,and elements integrated into,neural probes has also led to the necessity to create flexible interfaces,reducing neural tissue damage during probe implantation and increasing the quality of neural acquisition data.In this paper,we review the fabrication,characterization,and validation of several types of flexible neural probes,exploring the main advantages and drawbacks of these devices.Finally,future developments and applications are covered.Overall,this review aims to present the currently available flexible devices and future appropriate avenues for development as possible guidance for future engineered devices.