Energy harvesting from cerebrospinal fluid pressure fluctuations for self-powered neural implants

Abstract

In this paper, a novel method to generate electrical energy by converting available mechanical energy from pressure fluctuations of the cerebrospinal fluid within lateral ventricles of the brain is presented. The generated electrical power can be supplied to the neural implants and either eliminate their battery need or extend the battery lifespan. A diaphragm type harvester comprised of piezoelectric material is utilized to convert the pressure fluctuations to electrical energy. The pressure fluctuations cause the diaphragm to bend, and the strained piezoelectric materials generate electricity. In the framework of this study, an energy harvesting structure having a diameter of 2.5 mm was designed and fabricated using microfabrication techniques. A 1:1 model of lateral ventricles was 3D-printed from raw MRI images to characterize the harvester. Experimental results show that a maximum power of 0.62 nW can be generated from the harvester under similar physical conditions in lateral ventricles which corresponds to energy density of 12.6 nW/cm. Considering the available area within the lateral ventricles and the size of harvesters that can be built using microfabrication techniques it is possible to amplify to power up to 26 nW. As such, the idea of generating electrical energy by making use of pressure fluctuations within brain is demonstrated in this work via the 3D-printed model system.

Implantable microfluidics: methods and applications

“…For instance, implantable microfluidic systems can harvest energy from biological fluids such as blood flow or cerebrospinal fluid, converting the mechani-cal or chemical energy into electrical energy to power implanted sensors or therapeutic devices. 113,114 The ability to harvest energy and serve as a power source within the human body or in surrounding environments offers great potential for the development of long-lasting and autonomous implantable devices, reducing the need for frequent battery replacements or external power sources. 115 While implantable microfluidic devices as energy harvesters or power sources are not yet widely implemented, there is immense potential for their future integration.…”

Developments in Deep Brain Stimulators for Successful Aging Towards Smart Devices—An Overview

“…Several mechanisms for this have been explored in literature constituting mechanical energy, radio frequency, ultrasound, and thermal ( Shi et al, 2018 ; Zhao et al, 2020 ; Zou et al, 2021 ). One work demonstrated the potential of harvesting ambient mechanical energy from pressure fluctuations in the CSF within the lateral ventricles of the brain ( Beker et al, 2017 ). In general, the harvester should be designed to have the maximum efficiency possible and should be positioned where there are maximum physical stimuli while having minimal coupling loss.…”

Challenges in Scaling Down of Free-Floating Implantable Neural Interfaces to Millimeter Scale

“…The potential of collecting mechanical energy induced by pressure fluctuations in the cerebrospinal fluid (CSF) within the lateral ventricles is explored. Energy density of 12.6 nW/cm 2 was generated using such energy harvesting device (2.5 mm in diameter) and is possible to be increased up to 26 nW given the available space in the largest cavities of the ventricular system [101]. The very nature of the mechanism this approach utilizes, the need of space for motion or vibration, inadvertently renders it less efficient when it is scaled down.…”