Thermal analysis of injectable, cellular-scale optoelectronics with pulsed power

Abstract

An ability to insert electronic/optoelectronic systems into precise locations of biological tissues provides powerful capabilities, especially in neuroscience such as optogenetics where light can activate/deactivate critical cellular signalling and neural systems. In such cases, engineered thermal management is essential, to avoid adverse effects of heating on normal biological processes. Here, an analytic model of heat conduction is developed for microscale, inorganic light-emitting diodes (μ-ILEDs) in a pulsed operation in biological tissues. The analytic solutions agree well with both three-dimensional finite-element analysis and experiments. A simple scaling law for the maximum temperature increase is presented in terms of material (e.g. thermal diffusivity), geometric (e.g. μ-ILED size) and loading parameters (e.g. pulsed peak power, duty cycle and frequency). These results provide useful design guidelines not only for injectable μ-ILED systems, but also for other similar classes of electronic and optoelectronic components.

Closed-Loop and Activity-Guided Optogenetic Control

“…Implantable devices like miniaturized LEDs not only cannot alone provide such readout capability, but can also emit substantial heat, the effects of which must be carefully measured and/or controlled for in vivo (Yizhar et al, 2011a; Li et al, 2013b; Yeh et al, 2014, Society for Neuroscience abstract). LED-based devices can be designed with more inputs and outputs, but any associated increase in size and complexity may lead to more damage to tissue when implanted (a caveat not unique to electro-optical devices).…”

Mechanics and thermal management of stretchable inorganic electronics

“…[69] further extended the above model to perform thermal management of μ -ILEDs in optogenetics. Figs 17a and b show injectable, cellular-scale μ -ILEDs, which are inserted into the brain of mouse [70].…”

Miniaturized optogenetic neural implants: a review

“…Third, optical stimulation parameters should be optimized to enable effective opsin activation, while preventing the overheating of brain tissue. In order to reduce electrical heat generated during the operation of µLEDs, the thermal performance of µLEDs has been explored analytically and experimentally 68,93,101,102 . LEDs with different dimensions were fabricated 68 on a poly(ethyleneterephthalate) (PET) substrate.…”