Three children are raising £20,000 to fund bionic arms for Christmas . Caleb and Lennon, both nine, and eight-year-old Imogen, all born with one arm each, were picked for the Big Hero 3 campaign - which aims to raise the money to give a bionic arm to each child. The bionic arm , named the "Hero Arm", is the world's first multi-grip bionic arm for children. The campaign has already raised more than £2,000, but needs help to reach the £20,000 target by mid-November - so the children can receive