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Activity Funded

Microelectromechanical Systems Research Unit

Unidade de Investigação em Microssistemas Eletromecânicos

Reference
UIDP/04436/2020
Project Start Date
2020-01-01
Project End Date
2024-12-31
Principal Investigator
Scientific Area
Engineering and technology
Funding Program
Concurso de avaliação no âmbito do Programa Plurianual de Financiamento de Unidades de I&D (2017/2018) - Financiamento Programático

Abstract

10.2 Summary in English for general dissemination purposes The strategic program is addressing in particular the health area, with the emphasis on medical devices and with two innovative demonstrators: a multifunctional (electrical invasive and non-invasive, optical and thermal) neural probe (MULTINEURAL) and a smart hip implant (SHI). The MULTINEURAL project proposes to develop arrays of multifunctional microprobes for high temporal and spatial resolution brain studies. The arrays will incorporate 3D microelectrodes with embedded signal processing electronics. Microelectrodes will be designed for insertion in any part of cerebral cortex. They will integrate advanced features such optical sensing and stimulation (CMOS image sensor with optical filters and microlenses, microLEDs), cooling stimulation (nanostructured thermoelectric materials), besides the electrical recording and stimulation. Also, a non-invasive method for deep brain stimulation via temporally interference of multiple electric fields will be developed. The second medical-type of device to be addressed is a SHI. Stress shielding is one of the major drawbacks of joint prosthesis. A hip prosthesismay last for 5-10 years before sufficient stress shielding occurs that the prosthesis loosens enough to be symptomatic. The loose prosthesis is then removed by the orthopedist, and a new one is put in. However, the native bone around the original femoral component has substantially diminished bone stock so that the replacement cannot go on forever, since it eventually runs out of undisturbed bone in which to seat the prosthesis. A new approach to design, develop, manufacture, test and validate a SHI is proposed here. The approach merges the potential and benefits of new hybrid additive-subtractive processing technologies, functional materials, sensorized areas, actuating areas and remote monitoring (using MEMS devices) enabling to fully integrate the several components in the prosthesis during its processing. Regarding the component processing, an innovate approach based on a nano-micro-macro-level processing method with 3D degrees-of-freedom of material chemical composition is proposed. The manufacturing process enables the use of different materials locally positioned in different places of the component, and permits the creation of different cellular patterns along the component. This solution allows for the mimic, as close as possible, real boneswhere different materials, and different mechanical properties are tailored in each point of the component. Regarding other components functions, this project intends to use small size, lightweight, low power-consumption MEMS for sensing/monitoring of physiological aspects such as pressure (stress shielding), temperature (infections), micro-antennas (information transfer to exterior - wireless monitoring) and actuating devices/materials as piezo-electrics (osseo-integration) or shape memory alloys (changing components size to promote contact with bone), inside the human body. 10.3 Summary in English for evaluation The strategic program is addressing two innovative demonstrators: a multifunctional neural probe (MULTINEURAL) and a smart hip implant (SHI). The MULTINEURAL project proposes to develop arrays of multifunctional microprobes for high temporal and spatial resolution brain studies. The arrays will incorporate 3D microelectrodes with embedded signal processing electronics. Microelectrodes will be designed for insertion in any part of cerebral cortex. They will integrate advanced features such optical sensing and stimulation (CMOS image sensor with optical filters and microlenses, microLEDs), cooling stimulation (nanostructured thermoelectric materials), besides the electrical recording and stimulation. Also, a non-invasive method for deep brain stimulation via temporally interference of multiple electric fields will be developed in collaboration with the group of Prof. Edward Boyden (MIT Media Lab., Cambridge, USA). Optogenetics tools (optrodes) represents a device optimized for delivering light into a cell population genetically modified to show specific biological effects when exposed to light. Moreover, the combination between optrodes and optical imaging magnifies the profits of brain probes, considering microLEDs for neurons photostimulation (PS) and fluorophores excitation, and a CMOS image sensor (CMOS-IS) to measure the emitted fluorescence, which indicates the cell status. Introducing microLEDs and a CMOS-IS on a neural probe increases the spectrum of available wavelengths in a single probe enabling simultaneous stimulation and inhibition of different target cells in brain volume and the required wavelengths for optical imaging. However, two major problems emerge: 1) sometimes the required wavelengths for PS and optical imaging are to close, which interfere with the optical imaging that must only read the emitted light and reject the light from the µ-LEDs; and 2) the µ-LEDs emission irradiance needs to be at least 1 mW/mm2 for cells PS. MicroLEDs hardly have the emission irradiance required and although increasing the microLEDs power could solve the problem, it presents another issue with neurons overheat and high-power consumption. This project proposes the empowering of microLEDs and CMOS-IS, using Fabry Perot optical filters (a multilayer of thin films) and polydimethylsiloxane (PDMS) microlenses, fabricated on their surface. The optical filters will allow a narrowband, improving the selectivity of the system for a required stimulation and optical imaging. The PDMS microlenses will allow the light collimation, optimizing the incident light in the CMOS-IS and the emission irradiation of the microLEDs, ultimately improving the spatial resolution of the system. There are a number of ways in which to inactivate cortex that differ in reversibility, magnitude, and duration of sustained effects. The cooling technique with a neural probe for cortical inactivation will produce a reversible, highly localized inhibition of neuronal activity when the temperature of neurons is reduced to 20-24°C. The neural probe will integrate a thermoelectric device based in nanostructured Bi2Te3/Sb2Te3 materials. The enhancement is achieved by controlling the transport of phonons and electrons in the superlattices. The second medical-type of devices to be addressed deals with a new SHI solution. Stress shielding is one of the majordrawbacks of joint prosthesis. A hip prosthesis may last for 5-10 years before sufficient stress shielding occurs that the prosthesis loosens enough to be symptomatic. The loose prosthesis is then removed by the orthopedist, and a new one is put in. However, the native bone around the original femoral component has substantially diminished bone stock so that the replacement cannot go on forever, since it eventually runs out of undisturbed bone in which to seat the prosthesis. In the European region (500 million inhabitants in 28 countries) 1.360.000 hip and knee joint replacements take place every year, most of them due to stress shielding. A new approach to design, develop, manufacture, test and validate a SHI is proposed here. The approach merges the benefits of new processing technologies, functional materials, sensors, actuators and remote monitoring (using MEMS devices) enabling to fully integrate the several components in the prosthesis during its processing. The method is based on a micro-level processing enabling 3D degree-of-freedom of material chemical composition. The manufacturing process, a multi-material laser sintering process, previously developed, enables the use of different materials locally positioned in different places of the component, and permits the creation of different cellular patterns along the component. This approach allows to mimic, as close as possible, real bones where different materials, and different mechanical properties are tailored in each point of the component. This project intends to use small size, lightweight, low power-consumption MEMS for sensing/monitoring of physiological aspects such as pressure (stress shielding), temperature (infections), micro-antennas (wireless link) and actuating devices/materials as piezo-electrics (osseo-integration) or shape memory alloys (changing components size to promote contact with bone), inside the human body. In vivo sensors are now being used during surgery or for a short period after surgery, or for immediate inspection, but devices meant for permanent implantation hardly exist. Optimization to enable the real-time creation or built-up of some sensing/actuating devices such as piezo-electrics actuators, shape memory alloys (as actuators) or micro-antennas is needed. The goal is direct component creation during the manufacturing process to give origin to fully integrated smart components/devices. Once this challenge is achieved, the technology would represent a worldwide major step forward on smart components processing and integration, as compared to existing processing technologies.

Institutions

Main Institutions

  • Universidade do Minho Labbels (CMEMS-UMinho/UM)
  • Universidade do Minho (UMinho)

Funding 356.250,00 €

Fundação para a Ciência e a Tecnologia (FCT) - Portugal

356.250,00 €