US Patent 11689119 Variable stiffening device comprising electrode stacks in a flexible envelope

A variable stiffening device that includes a flexible envelope having a fluid chamber, a dielectric fluid housed within the fluid chamber, and an electrode stack that includes a plurality of electrodes and one or more abrasive strips. The electrode stack is housed within the fluid chamber and is configured to receive voltage. In addition, the one or more abrasive strips are each positioned between adjacent electrodes, such that when voltage is applied to the electrode stack thereby electrostatically drawing adjacent electrodes together, the one or more abrasive strips generate frictional engagement between adjacent electrodes to actuate the variable stiffening device from a relaxed state to a rigid state.