X-optogenetics and U-optogenetics: Feasibility and Possibilities
  To address these limitations of optogenetics, here we propose two new methods for optogenetic stimulation. The first is x-optogenetics, which uses visible light-emitting nanophosphors stimulated by focused x-rays. This idea is not new but the application to optogenetics is novel. X-rays can penetrate much more deeply than infrared light and could allow for nerve cell stimulation in any part of the brain. In this paper, we discuss the feasibility and possibilities of such a method by describing the advances in nanomaterials, x-ray focusing, and x-ray sources. Also, we discuss concerns when dealing with x-rays such as radiation dosage. Through the use of quantities and assumptions backed by recent literature, manufacturer specifications, and personal correspondence, a full feasibility analysis of x-optogenetics is completed. The second proposed method we explore is u-optogenetics, which is the application of sonoluminescence to optogenetics. Such a technique uses ultrasound waves instead of x-rays to induce light emission, so there would be no introduction of radiation. However, the penetration depth of ultrasound is less than that of x-ray. The key issues affecting feasibility are laid out for further investigation into both x-optogenetics and u-optogenetics. 
Rachel Berry, Matthew Getzin, Lars Gjesteby, and Ge Wang
physics.bio-ph physics.med-ph