MIT engineers have built a fast, ultra-broadband, low-power radio chip, modelled on the human inner ear, that could enable wireless devices capable of receiving cell phone, Internet, radio and television signals. Rahul Sarpeshkar, associate professor of electrical engineering and computer science, and his graduate student, Soumyajit Mandal, designed the chip to mimic the inner ear, or cochlea. The chip is claimed to be faster than any human-designed radio-frequency spectrum analyser and also operates at much lower power,reports efytimes.
The RF cochlea mimics the structure and function of the biological cochlea, which uses fluid mechanics, piezoelectrics and neural signal processing to convert sound waves into electrical signals that are sent to the brain.
As sound waves enter the cochlea, they create mechanical waves in the cochlear membrane and the fluid of the inner ear, activating hair cells (cells that cause electrical signals to be sent to the brain). The cochlea can perceive a 100-fold range of frequencies -- in humans, from 100 to 10,000 Hz. Sarpeshkar used the same design principles in the RF cochlea to create a device that can perceive signals at million-fold higher frequencies, which includes radio signals for most commercial wireless applications.
The RF cochlea, embedded on a silicon chip measuring 1.5 mm by 3 mm, works as an analogue spectrum analyser, detecting the composition of any electromagnetic waves within its perception range. Electromagnetic waves travel through electronic inductors and capacitors (analogous to the biological cochlea's fluid and membrane). Electronic transistors play the role of the cochlea's hair cells.
The analogue RF cochlea chip is faster than any other RF spectrum analyser and consumes about 100 times less power than what would be required for direct digitisation of the entire bandwidth. That makes it desirable as a component of a universal or 'cognitive' radio, which could receive a broad range of frequencies and select which ones to attend to.
This is not the first time Sarpeshkar has drawn on biology for inspiration in designing electronic devices. Trained as an engineer but also a student of biology, he has found many similar patterns in the natural and man-made worlds.
