Globalpress: Stanford implants IC in a bloodcell
Lack of industrial interest in funding research into chips which can be implanted into the body to deliver medical benefits is holding up their commercialisation, says Dr Ada Poon, Assistant Professor at the Stanford School of Engineering.
?The devices receive signals from a radio transmitter outside the body sending signals to a magnetically coupled receiver in the device.
The school has built a 2mm x 2mm wireless locomotive implant which travels through the body to deliver, sensors drugs or cameras to exactly the required location in the body. The implant has a motor to allow movement. One milliamp of current allows the implant to move at a speed of one centimetre a second.
The direction of the locomotive can be controlled from outside the body by magnetic transmission. Current loops on the implant can generate magnetic movement in any 3D direction.
The chip contains a rectifier and bandgap reference, a demodulator, the propulsion system, a digital controller and a regulator. The propulsion system requires 250 microWatts and the whole chip 267 microWatts.
The implant can be swallowed or injected.
A microTag measuring 18microns by 7 has been implanted in a bloodcell by the school. The cell can survive for five days with the tab inside it, said Poon. Transmissions from the tag allow a sensing capability of the cell.
Asked about commercialization of the technology Poon replied. “The semiconductor industry won’t fund this kind of research because it doesn’t make money.”
The school has developed 1mm x 0.32mm iProbes for the heart to detect the relative timings of the electrical signals in the heart to cope with irregular heartbeat – arrhythmia. They make possible the wireless probing of the heart.
The school is also about to prove the concept of wireless charging of an implant from outside the body.
“The problem with pacemakers is the battery,” said Poon, “we want to eliminate it with wireless power transmission.”
“Most studies on wireless power transmission omit the displacement current,” said Poon, “we have built a power receiver at 1GHz that is 100x smaller at the same power transfer efficiency and range. That’s the optimal frequency for wireless power transfer in a homogeneous medium.”
Discovering this frequency was Dr Poon’s big breakthrough. Before her discovery, the frequencies used required antennae in the receiver which were too big to be implanted.
Once again, the problem with developing this technology to the point where it can help people with pacemakers is the lack of industrial interest in funding the research, said Poon.