System Bits: June 2

Biosensor chip for precise medicine; algorithm for autonomous robots; light-based computing.

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Subcutaneous medicine chip
A biosensor chip developed at EPFL is capable of simultaneously monitoring the concentration of a number of molecules, such as glucose and cholesterol, and certain drugs.

It’s only a centimeter long, placed under a patient’s skin, powered by a patch on the surface of the skin, and communicates with a mobile phone.

(Source: EPFL)

(Source: EPFL)

EPFL researchers stressed that the future of medicine lies in ever greater precision, not only when it comes to diagnosis but also drug dosage. The blood work that medical staff rely on is generally a snapshot indicative of the moment the blood is drawn before it undergoes hours – or even days – of analysis.

To this end, several EPFL laboratories are working on devices allowing constant analysis over as long a period as possible. The latest development is this biosensor chip, created by researchers in the Integrated Systems Laboratory working together with the Radio Frequency Integrated Circuit Group.

The team said this is the world’s first chip capable of measuring not just pH and temperature, but also metabolism-related molecules like glucose, lactate and cholesterol, as well as drugs. A group of electrochemical sensors works with or without enzymes, which means the device can react to a wide range of compounds, and it can do so for several days or even weeks.

The device measures one square centimeter and contains three main components: a circuit with six sensors, a control unit that analyses incoming signals, and a radio transmission module. It also has an induction coil that draws power from an external battery attached to the skin by a patch. A simple plaster holds together the battery, the coil and a Bluetooth module used to send the results immediately to a mobile phone.

Autonomous robot algorithm
According to researchers at MIT, today’s industrial robots are remarkably efficient — as long as they’re in a controlled environment where everything is exactly where they expect it to be. Put them in an unfamiliar setting, where they have to think for themselves, and their efficiency plummets. In addition, the difficulty of on-the-fly motion planning increases exponentially with the number of robots involved. For even a simple collaborative task, a team of, say, three autonomous robots might have to think for several hours to come up with a plan of attack.

Interestingly, MIT researchers have created a new algorithm that can significantly reduce robot teams’ planning time. The plan the algorithm produces may not be perfectly efficient, but in many cases, the savings in planning time will more than offset the added execution time, they said.

MIT researchers tested the viability of their algorithm by using it to guide a crew of three robots in the assembly of a chair. (Source: MIT)

MIT researchers tested the viability of their algorithm by using it to guide a crew of three robots in the assembly of a chair.
(Source: MIT)

Light-based computing
Given that light can transmit more data while consuming far less power than electricity, a technological advancement by Stanford University electrical engineers brings optical data transport closer to replacing wires in order to make computers faster and more efficient by reinventing how they send data back and forth between chips.

Infrared light enters this silicon structure from the left. The cut-out patterns, determined by an algorithm, route two different frequencies of this light into the pathways on the right. This is a greatly magnified image of a working device that is about the size of a speck of dust. (Source: Stanford University)

Infrared light enters this silicon structure from the left. The cut-out patterns, determined by an algorithm, route two different frequencies of this light into the pathways on the right. This is a greatly magnified image of a working device that is about the size of a speck of dust. (Source: Stanford University)

The researchers reminded that today, in computers, data is pushed through wires as a stream of electrons; this takes a lot of power, and helps explain why laptops get so warm. Specifically, up to 80 percent of the microprocessor power is consumed by sending data over the wires – so-called interconnects.

To address this, the Stanford team developed a process that they believe could revolutionize computing by making it practical to use light instead of electricity to carry data inside computers by miniaturizing the proven technology of the Internet, which moves data by beaming photons of light through fiber optic threads.

Optical transport uses far less energy than sending electrons through wires, and for chip-scale links, light can carry more than 20 times as much data. Theoretically, this is doable because silicon is transparent to infrared light – the way glass is transparent to visible light. So wires could be replaced by optical interconnects: silicon structures designed to carry infrared light.

So far, however, optical interconnects have been designed one at a time, and given that thousands of such linkages are needed for each electronic system, optical data transport has remained impractical.

But the Stanford engineers now believe they’ve broken that bottleneck by inventing what they call an inverse design algorithm that works as the name suggests: the engineers specify what they want the optical circuit to do, and the software provides the details of how to fabricate a silicon structure to perform the task. This has been used to design a working optical circuit and the team has made several copies in the lab.