Biomechatronics is an applied interdisciplinary science that aims to integrate mechanical elements, electronics and parts of biological organisms. Biomechatronics includes the aspects of biology, mechanics, and electronics. It also encompasses the fields of robotics and neuroscience. One example of Biomechatronics is a study done by Hugh Herr, a professor at MIT. Herr excised the muscles of frog legs, to attach to a mechanical fish and by pulsing electrical current through the muscle fibers, he caused the fish to swim. The goal of these experiments is to make devices that interact with human muscle, skeleton, and nervous systems. The end result is that the devices will help with human motor control that was lost or impaired by trauma, disease or birth defects.
How it works 
Biomechatronics is how the human body works. For example, four different steps must occur to be able to lift the foot to walk. First, impulses from the motor center of the brain are sent to the foot and leg muscles. Next the nerve cells in the feet send information to the brain telling it to adjust the muscle groups or amount of force required to walk across the ground. Different amounts of force are applied depending on the type of surface being walked across. The leg's muscle spindle nerve cells then sense and send the position of the floor back up to the brain. Finally, when the foot is raised to step, signals are sent to muscles in the leg and foot to set it down.
Biosensors are used to detect what the user wants to do or their intentions and motions. In some devices the information can be relayed by the user's nervous system or muscle system. This information is related by the biosensor to a controller which can be located inside or outside the biomechatronic device. In addition biosensors receive information about the limb position and force from the limb and actuator. Biosensors come in a variety of forms. They can be wires which detect electrical activity, needle electrodes implanted in muscles, and electrode arrays with nerves growing through them.
Mechanical sensors 
The purpose of the mechanical sensors is to measure information about the biomechatronic device and relate that information to the biosensor or controller.
The controller in a biomechatronic device relays the user's intentions to the actuators. It also interprets feedback information to the user that comes from the biosensors and mechanical sensors. The other function of the controller is to control the biomechatronic device's movements.
The actuator is an artificial muscle. Its job is to produce force and movement. Depending on whether the device is orthotic or prosthetic the actuator can be a motor that assists or replaces the user's original muscle.
Biomechatronics is a rapidly growing field but as of now there are very few labs which conduct research. The Rehabilitation Institute of Chicago, University of California at Berkeley, MIT, and University of Twente in the Netherlands are the researching leaders in biomechatronics. Three main areas are emphasized in the current research.
- Analyzing human motions, which are complex, to aid in the design of biomechatronic devices
- Studying how electronic devices can be interfaced with the nervous system.
- Testing the ways to use living muscle tissue as actuators for electronic devices
Analyzing motions 
A great deal of analysis over human motion is needed because human movement is very complex. MIT and the University of Twente are both working to analyze these movements. They are doing this through a combination of computer models, camera systems, and electromyograms.
Interfacing allows biomechatronic devices to connect with the muscle systems and nerves of the user in order send and receive information from the device. This is a technology that is not available in ordinary orthotics and prosthetics devices. Groups at the University of Twente are making drastic steps in this department. Scientists there have developed a device which will help to treat paralysis and stroke victims who are unable to control their foot while walking. The researchers are also nearing a breakthrough which would allow a person with an amputated leg to control their prosthetic leg through their stump muscles.
MIT research 
Hugh Herr is the leading biomechatronic scientist at MIT. Herr and his group of researchers are developing a sieve integrated circuit electrode and prosthetic devices that are coming closer to mimicking real human movement. The two prosthetic devices currently in the making will control knee movement and the other will control the stiffness of an ankle joint.
Robotic fish 
As mentioned before Herr and his colleagues made a robotic fish that was propelled by living muscle tissue taken from frog legs. The robotic fish was a prototype of a biomechatronic device with a living actuator. The following characteristics were given to the fish.
- A styrofoam float so the fish can float
- Electrical wires for connections
- A silicone tail that enables force while swimming
- Power provided by lithium batteries
- A microcontroller to control movement
- An infrared sensor enables the microcontroller to communicate with a handheld device
- Muscles stimulated by an electronic unit
Arts research 
New media artists at UCSD are using biomechatronics in performance art pieces, such as Technesexual (more information, photos, video), a performance which uses biometric sensors to bridge the performers' real bodies to their Second Life avatars and Slapshock (more information, photos,video), in which medical TENS units are used to explore intersubjective symbiosis in intimate relationships.
The demand for biomechatronic devices are at an all-time high and show no signs of slowing down. Many biomechatronic researchers are closely collaborating with military organizations. The US Department of Veterans Affairs and the Department of Defense are giving funds to different labs to help soldiers and war veterans 
See also 
- Biomedical engineering
- Brain-computer interface
- Neural engineering
- Biomechatronics lab at MIT
- Biomechatronics lab at the Rehabilitation Institute of Chicago
- Biomechatronics lab at University of Twente
- Experimental Biomechatronics Lab at Carnegie Mellon University
- Laboratory for Biomechatronics at the University of Lübeck