For people with spinal-cord injuries, just trying to feed themselves or pick up objects can be exhausting and frustrating. MIT researchers Kailas Narendran and John McBean, working with mechanical engineer Woodie Flowers, have built a powered elbow brace that allows patients to bend and extend their arms under their own control. Carried in a hip pack is a small electric motor that drives the elbow brace via a set of miniature cables. Electrodes placed on the skin pick up electrical signals from the biceps muscle as the wearer flexes his or her arm; a control box interprets these signals and commands the motor to move the elbow joint with just the right amount of force to let the patient, for instance, wave or pick up a cup. Initial tests have been completed on spinal-injury patients at Spaulding Rehabilitation Hospital in Boston; a larger clinical study is now under way, says Narendran, who with McBean is starting up a company this summer to develop the product.