New York, Oct 29 : A new smartphone case under $50 could soon enable people with visual impairments, tremors and spasms to use touch screens independently. Developed at the University of Michigan in the US, the case named 'BrushLens' could help users perceive, locate and tap buttons and keys on the touch screen menus now ubiquitous in restaurant kiosks, ATM machines and other public terminals. Users can comb through a touch screen interface by holding a phone connected to BrushLens against a touch screen and dragging the phone across the screen. The phone sees what's on the screen with its camera then reads the options aloud by harnessing the phone's built-in screen readers. Users indicate their menu choice through screen readers or an enlarged, easy-to-tap button in the BrushLens app. "So many technologies around us require some assumptions about users' abilities, but seemingly intuitive interactions can actually be challenging for people," said Chen Liang, a doctoral student in computer science and engineering. "People have to be able to operate these inaccessible touch screens in the world. Our goal is to make that technology accessible to everyone," Liang added. Liang and Anhong Guo, assistant professor of computer science and engineering developed BrushLens with Alanson Sample, an associate professor in the same department. When given a target, BrushLens divides the screen into a grid, then guides the user's hand toward the section of the screen containing their menu choice by saying the coordinates of both the target and device. Once those coordinates overlap, pushbuttons or autoclickers on the underside of the phone case tap the screen for the user, depending on the model. "The user doesn't have to precisely locate where the button is and perform the touch gesture," Liang said. Ten study participants, six with visual impairments and four with tremors or spasms, tested the hardware and app. For one participant with cerebral palsy, BrushLens improved their accuracy by nearly 74 per cent. The inventors of BrushLens recently applied for a patent with the help of Innovation Partnerships, U-M's central hub for research commercialization. The team hopes to bring the product to users as an affordable phone accessory. "The parts that we used are relatively affordable. Each clicker costs only $1," Liang said. "The whole device is definitely under $50, and that's a conservative estimate. /IANS