Neural implants are set to be revolutionised by a new type of graphene transistor with a liquid gate. The emerging technology of neural prostheses has the power to change what it means to be human. The ability to implant electrodes into the eyes ears, spine or even the brain has the potential to overcome degenerative disease, mend broken bodies and even enhance our senses with superhuman abilities.
But despite numerous trials of electronic devices implanted into the human body, there are still many challenges ahead. The problem is that most of these devices are based on silicon substrates which are hard, rigid and sharp. Those are not normally qualities that sit well with soft tissue.
Graphene solution-gated field effect transistors (SGFETs) and their applications in bioelectronics. The fabrication and characterization of arrays of graphene SGFETs is presented and discussed with respect to competing technologies. To obtain a better understanding of the working principle of solution-gated transistors, the graphene-electrolyte interface is discussed in detail. The in-vitro biocompatibility of graphene is assessed by primary neuron cultures. Finally, bioelectronic experiments with electrogenic cells are presented, confirming the suitability of graphene to record the electrical activity of cells.
Concept for a retinal implant. An image is acquired by a camera which is mounted to eyeglasses. After processing, the information is transferred to a retinal implant which stimulates nerve cells to transmit the signal to the brain.
In this article, we have provided some insight on fundamental aspects of graphene solution-gated field effect transistors, and at the same time we have discussed their use as transducers for the recording of the electrical activity of living cells.
We have shown that due to its outstanding chemical, electrical, and mechanical properties, graphene is an ideal material for the fabrication of bioelectronic devices based on field effect transistors. In particular, the high mobility of carriers in graphene together with the singular double layer formed at the graphene/electrolyte interface results in FET devices which far outperform current technologies in terms of their gate sensitivity. Further, even at this relatively early stage of development, graphene FETs exhibit a noise performance that equals or even surpasses that of already well-established technologies. New advancements in the growth of high quality graphene are expected to further increase the substantial advantages of graphene for sensing applications.
Looking beyond the state of the art described in this article, the challenge resides in the development of high performance graphene-based devices on flexible substrates. Provided that this issue can be successfully addressed, graphene-based SGFETs have the potential to set a new paradigm in bioelectronics and, in particular, in the field of neural prostheses.
SOURCES- Arxiv, Technology Review