The researchers have integrated a conventional solid-state complementary metal-oxide-semiconductor (CMOS) integrated circuit with an artificial lipid bilayer membrane containing ATP-powered ion pumps. The solution paves the way to creating new artificial systems that contain both biological and solid-state components. The study, led by Ken Shepard, Lau Family Professor of Electrical Engineering and professor of biomedical engineering at Columbia Engineering, has been published online in Nature Communications.
“In combining a biological electronic device with CMOS, we will be able to create new systems not possible with either technology alone,” said Shepard. “We are excited at the prospect of expanding the palette of active devices that will have new functions, such as harvesting energy from ATP, as was done here, or recognizing specific molecules, giving chips the potential to taste and smell.”
Shepard, whose lab is a leader in the development of engineered solid-state systems interfaced to biological systems, noted that despite its success, CMOS solid-state electronics is incapable of replicating certain functions natural to living systems, such as the senses of taste and smell and the use of biochemical energy sources. Living systems achieve this functionality with their own version of electronics based on lipid membranes and ion channels and pumps, which act as a kind of ‘biological transistor’. They use charge in the form of ions to carry energy and information – ion channels control the flow of ions across cell membranes. Solid-state systems, such as those in computers and communication devices, use electrons; their electronic signaling and power are controlled by field-effect transistors.
In living systems, energy is stored in potentials across lipid membranes, in this case created through the action of ion pumps. ATP is used to transport energy from where it is generated to where it is consumed in the cell. To build a prototype of their hybrid system, Shepard’s team, led by PhD student Jared Roseman, packaged a CMOS integrated circuit (IC) with an ATP-harvesting ‘biocell’. In the presence of ATP, the system pumped ions across the membrane, producing an electrical potential harvested by the IC.
“We made a macroscale version of this system, at the scale of several millimeters, to see if it worked,” explained Shepard. “Our results provide new insight into a generalized circuit model, enabling us to determine the conditions to maximize the efficiency of harnessing chemical energy through the action of these ion pumps. We will now be looking at how to scale the system down.”
While other groups have harvested energy from living systems, Shepard and his team are exploring how to do this at the molecular level, isolating just the desired
function and interfacing this with electronics. “We don’t need the whole cell,” explained Shepard. “We just grab the component of the cell that’s doing what we want.
For this project, we isolated the ATPases because they were the proteins that allowed us to extract energy from ATP.”
“With appropriate scaling, this technology could provide a power source for implanted systems in ATP-rich environments such as inside living cells,” added Roseman.
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