While the human brain may make us what we are, our sensory systems are our windows and doors to the world. Infact they are our ONLY windows and doors to the world. So when one of these systems fails, the corresponding partof our world is no longer accessible to us. Recent advances in engineering have made it possible to replace sensorysystems by mechanical and electrical sensors, and to couple those sensors electronically to our nervous system.While to many this may sound futuristic and maybe even a bit scary, it can work magically. For the auditory system,so called "cochlea implants" have given thousands of patients who were completely deaf their hearing back, so thatthey can interact and communicate freely again with their family and friends. Many research groups are alsoexploring different approaches to retinal implants, in order to restore vision to the blind. And in 2010 the first patienthas been implanted with a "vestibular implant", to alleviate defects in his balance system.

The wikibook "Biological Machines" wants to present our sensory system from an engineering and informationprocessing point of view. On the one hand, this provides some insight in the sometimes spectacular ingenuity andperformance of our senses. On the other hand, it provides some understanding of how our senses transduce externalinformation into signals that our central nervous system can work with, and how - and how well - this process canbe replaced by technical components.