BTY100-Lec#6.3 Biomedical Engineering Bionics

Outline Bionics: Basic concept Bionic Arms Powered Exoskeleton Bionic Legs

BIONICS Bionics is the application of methods and systems found in nature to the study and design of engineering systems. In medicine, Bionics usually means the replacement or enhancement of organs or other body parts by mechanical versions or electrical add ons. Building bionic limbs with machine intelligence that can sense their environment and predict a user's intentions.

Bionic Arm

BASIC REQUIREMENT The “bionic arm” technology is possible primarily because of two facts of amputation. The motor cortex in the brain is still sending out control signals even if certain voluntary muscles are no longer available for control; and When doctors amputate a limb, they don’t remove all of the nerves that once carried signals to that limb. So even if a person’s arm is gone , there are working nerve endings that end in the shoulder.

STRUCTURE

Bionic Arm Surgeons basically dissect the shoulder to access the nerve endings that control the movements of arm joints like the elbow, wrist and hand. Then, without damaging the nerves, they redirect the endings to a working muscle group. To use those signals to control the bionic arm, the setup places electrodes on the surface of the chest muscles. Each electrode controls one of the six motors that move the prosthetic arm’s joints

Bionic Arm When a person thinks “open hand,” the brain sends the “open hand” signal to the appropriate nerve, now located in the chest. When the nerve ending receives the signal, the chest muscle it’s connected to contracts. When the “open hand” chest muscle contracts, the electrode on that muscle detects the activation and tells the motor controlling the bionic hand to open. And since each nerve ending is integrated into a different piece of chest muscle, a person wearing the bionic arm can move all six motors simultaneously, resulting in a pretty natural range of motions for the prosthesis.

BIONIC LEGS

STRUCTURE

Working Mechanism Works in a manner Similar to Bionic Arm redirect nerves from damaged muscle in amputated limb to healthy hamstring muscle above his knee. When the redirected nerves instruct the muscles to contract, sensors on the patient’s leg detect tiny electrical signals from the muscles. A specially-designed computer program analyzes these signals and data from sensors in the robotic leg. It instantaneously decodes the type of movement the patient is trying to perform and then sends those commands to the robotic leg. Using muscle signals, instead of robotic sensors, makes the system safer and more intuitive.

POWERED EXOSKELETON is a mobile machine consisting primarily of an outer framework worn by a person, and powered by a system of motors or hydraulics that delivers at least part of the energy for limb movement. Function : assist the wearer by boosting their strength and endurance.

EXAMPLE Ekso Bionics is developing and manufacturing intelligently powered exoskeleton bionic devices that can be strapped on as wearable robots to enhance the strength, mobility, and endurance of soldiers and paraplegics.

EXAMPLE Activelink: plans to begin rollout of the first batch of 1000 starting in 2015. At its heart will be a lithium-ion battery pack that can provide for several hours of general purpose activity.

ReWalk is a commercial bionic walking assistance system, using powered leg attachments to enable paraplegics to stand upright, walk, and climb stairs. The system is powered by a backpack battery, and is controlled by a simple wrist-mounted remote which detects and enhances the user's movements.

Problems Encountered Power Supply Skeleton Actuators Joint flexibility Detection of unsafe/invalid motions