Artificial organs are made up of biological material or synthetic materials based on requirement and localized response of material with tissue. The surface of implants which is in contact with the body tissue made of a biomedical material or biomaterials such as titanium, silicone or apatite depending on what is the most functional and biocompatible. In some medical cases, implants contain electronics, e.g. artificial pacemakers for heart substitutes and cochlear implants for ear substitute. The implants are bioactive, such as subcutaneous drug delivery devices in the form of implantable pills or drug-eluting stents in order to induce the function. Bioartificial organs are also a focus area in research with major application, such as with hepatic assist devices that use liver cells within an artificial bioreactor construct.