Medical contact lens embedds wireless MEMs sensor

March 25, 2010 // Julien Happich

STMicroelectronics announced it will develop and supply a wireless MEMS sensor that acts as a transducer, antenna and mechanical support for additional read-out electronics in a breakthrough platform developed by Swiss company Sensimed AG. This solution will enable better management of glaucoma patients via earlier diagnosis and treatment that is optimally tailored to the individual patient.

Known as the Sensimed Triggerfish, the solution is based on a “smart” contact lens that uses a tiny embedded strain gauge to monitor the curvature of the eye over a period of, typically, 24 hours, providing valuable disease management data that is not currently obtainable using conventional ophthalmic equipment. 

Glaucoma3, the second most common cause of blindness around the world, is an irreversible progressive disease of the optic nerve that can eventually lead to blindness. 

Although it cannot be cured, its progress can be controlled once it is diagnosed and treated properly. The standard test is the measurement of intra-ocular pressure (IOP), using an instrument known as a tonometer, during periodic visits to an ophthalmologist.

However, the tonometer may fail to detect an elevated IOP, especially in glaucoma patients, because the pressure varies during the day and often peaks during sleep or outside of office hours. As a result, the disease is often diagnosed only after significant damage to the optic nerve has already occurred, and the disease keeps progressing in many patients due to inadequate treatment.

Sensimed's ingenious solution is a two-part system comprising the smart contact lens and a small receiver worn around the patient's neck. In addition to the strain gauge the lens contains an antenna, a tiny dedicated processing circuit and an RF transmitter to communicate the measurements to the receiver. 

The lens is powered via the received radio waves and does not need to be connected to a battery. The embedded components are positioned in the lens in such a way that they do not interfere with the patient's vision. The lens is fitted by the ophthalmologist and when the patient returns the next day the ophthalmologist removes the lens and receiver, obtaining a complete record of IOP changes over the preceding 24 hours.

The Sensimed Triggerfish has obtained the CE mark4, is currently running numerous application trials, and is commercially available in selected centers. ST engineers are now working with Sensimed to translate this breakthrough technology into a reliable commercial MEMS product ready for mass production.

ST expects the development of the MEMS sensor to be completed in Q2 2010 and manufacturing to start in Q3 2010, with availability outside trials to doctors and patients subject to regulatory approvals. Sensimed and ST anticipate progressively rolling out the product country-by-country across Europe beginning in Q3 and entering the US market by the end of 2011.  

“We have a strong focus on developing and manufacturing wireless sensor networks for diagnostics and other applications in medicine. This wireless, self-powered, on-body sensor will be used in a product that promises to greatly help the millions of people at risk and suffering from glaucoma,” said Benedetto Vigna, General Manager of STMicroelectronics' MEMS, sensors and high performance analog division.

Visit Sensimed at www.sensimed.ch

Visit STMicroelectronics at www.st.com

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