'Besides visual enhancement, noninvasive monitoring of the wearer’s biomarkers and health indicators could be a huge future market. We’ve built several simple sensors that can detect the concentration of a molecule, such as glucose. Sensors built onto lenses would let diabetic wearers keep tabs on blood-sugar levels without needing to prick a finger. The glucose detectors we’re evaluating now are a mere glimmer of what will be possible in the next 5 to 10 years. Contact lenses are worn daily by more than a hundred million people, and they are one of the only disposable, mass-market products that remain in contact, through fluids, with the interior of the body for an extended period of time. When you get a blood test, your doctor is probably measuring many of the same biomarkers that are found in the live cells on the surface of your eye—and in concentrations that correlate closely with the levels in your bloodstream. An appropriately configured contact lens could monitor cholesterol, sodium, and potassium levels, to name a few potential targets. Coupled with a wireless data transmitter, the lens could relay information to medics or nurses instantly, without needles or laboratory chemistry, and with a much lower chance of mix-ups. Three fundamental challenges stand in the way of building a multipurpose contact lens. First, the processes for making many of the lens’s parts and subsystems are incompatible with one another and with the fragile polymer of the lens. To get around this problem, my colleagues and I make all our devices from scratch. To fabricate the components for silicon circuits and LEDs, we use high temperatures and corrosive chemicals, which means we can’t manufacture them directly onto a lens. That leads to the second challenge, which is that all the key components of the lens need to be miniaturized and integrated onto about 1.5 square centimeters of a flexible, transparent polymer. We haven’t fully solved that problem yet, but we have so far developed our own specialized assembly process, which enables us to integrate several different kinds of components onto a lens. Last but not least, the whole contraption needs to be completely safe for the eye. Take an LED, for example. Most red LEDs are made of aluminum gallium arsenide, which is toxic. So before an LED can go into the eye, it must be enveloped in a biocompatible substance. So far, besides our glucose monitor, we’ve been able to batch-fabricate a few other nanoscale biosensors that respond to a target molecule with an electrical signal; we’ve also made several microscale components, including single-crystal silicon transistors, radio chips, antennas, diffusion resistors, LEDs, and silicon photodetectors. We’ve constructed all the micrometer-scale metal interconnects necessary to form a circuit on a contact lens. We’ve also shown that these microcomponents can be integrated through a self-assembly process onto other unconventional substrates, such as thin, flexible transparent plastics or glass. We’ve fabricated prototype lenses with an LED, a small radio chip, and an antenna, and we’ve transmitted energy to the lens wirelessly, lighting the LED. To demonstrate that the lenses can be safe, we encapsulated them in a biocompatible polymer and successfully tested them in trials with live rabbits.' // spectrum.ieee.org/biomedical/bionics/augmented-reality-in-a-contact-lens
Posted on: Mon, 26 Aug 2013 20:11:38 +0000
Trending Topics
Recently Viewed Topics
© 2015