S-MRUT: Sectored-Multi Ring Ultrasonic Transducer for selective powering of brain implants

One of the main challenges of the current ultrasonic transducers for powering brain implants is the complexity of focusing ultrasonic waves in various axial and lateral directions. The available transducers usually use electrically controlled phased array for beamforming the ultrasonic waves, which increases the complexity of the system even further. In this paper, we propose a straightforward solution for selective powering of brain implants to remove the complexity of conventional phased arrays. Our approach features a Sectored-Multi Ring Ultrasonic Transducer (S-MRUT) on a single piezoelectric sheet, specifically designed for powering implantable devices for optogenetics in freely moving animals. The proposed uni-directional S-MRUT is capable of focusing the ultrasonic waves on brain implants located at different depths and regions of the brain. The S-MRUT is designed based on Fresnel Zone Plate (FZP) theory, simulated in COMSOL, and fabricated with microfabrication process. The acoustic profile of the seven different configurations of the SMRUT were measured using a hydrophone with the total number of 7436 grid points. The measurements show the ability of the proposed S-MRUT to sweep the focus point of the acoustic waves in the axial direction in depths of 1 – 3mm, which is suitable for powering implants in the striatum of the mouse. Furthermore, the proposed S-MRUT demonstrates a steering area with the average radius of 0:862mm, and 0:678mm in experiments, and simulations, respectively. The S-MRUT is designed with the size of 3.8 × 3.8 × 0.5mm3 and the weight of 0:054gr, showing that it is compact and light enough to be worn by a mouse. Finally, the S-MRUT was tested in our measurement setup, where it successfully transfers sufficient power to a 2:8mm3 optogentic stimulator to turn on a microLED on the stimulator

Ultrasonically powered compact implantable dust for optogenetics

This paper presents an ultrasonically powered microsystem for deep tissue optogenetic stimulation. All the phases in developing the prototype starting from modelling the piezoelectric crystal used for energy harvesting, design, simulation and measurement of the chip, and finally testing the whole system in a mimicking setup are explained. The developed system is composed of a piezoelectric harvesting cube, a rectifier chip, and a micro-scale custom-designed light-emitting-diode (LED), and envisioned to be used for freely moving animal studies. The proposed rectifier chip with a silicon area of 300 μm × 300 μm is implemented in standard TSMC 0.18 μm CMOS technology, for interfacing the piezoelectric cube and the microLED. Experimental results show that the proposed microsystem produces an available electrical power of 2.2 mW while loaded by a microLED, out of an acoustic intensity of 7.2 mW/mm 2 using a (1 mm) 3 crystal as the receiver. The whole system including the tested rectifier chip, a piezoelectric cube with the dimensions of (500 μm) 3 , and a μLED of 300 μm × 130 μm have been integrated on a 3 mm × 1.5 mm glass substrate, encapsulated inside a bio-compatible PDMS layer and tested successfully for final prototyping. The total volume of the fully-packaged device is estimated around 2.85 mm 3

Realization of high efficiency ultrasound-powered micro-LEDs for optogenetics

We present the fabrication, characterization, and demonstration of high-efficiency ultrasound-powered micro- light emitting diodes (μLED) for use in optogenetic applications. InGaN based blue-emitting LED material wafers grown on a patterned sapphire substrate (PSS) were used to assist in the out-scattering of the light. The turn-on voltage of the LEDs is around 2.5 volts and the electrical ideality factor is 1.2 confirming high radiative recombination efficiency. A power density of more than 50 mW/mm2 was obtained from a 130 x 300 μm2 LED with a mesa of 100 μm diameter at 3 mA which is much more than is required to excite channelrhodopsin transfected neural cells. A high external quantum efficiency (EQE) of 33% is obtained at 3 mA measured in an integrating sphere. The peak wavelength of the μLED was measured at 483 nm at different current densities. The μLEDs are integrated directly onto a rectifier and Piezoelectric Transducer (PZT) harvester to realise a highly efficient ultrasound-powered light delivery unit capable to generate mWs of optical power. The concept was validated by powering the integrated device with ultrasound

Proteome Analysis of Pod and Seed Development in the Model Legume Lotus japonicus

Legume pods serve important functions during seed development and are themselves sources of food and feed. Compared to seeds, the metabolism and development of pods are not well-defined. The present characterization of pods from the model legume Lotus japonicus, together with the detailed analyses of the pod and seed proteomes in five developmental stages, paves the way for comparative pathway analysis and provides new metabolic information. Proteins were analyzed by two-dimensional gel electrophoresis and tandem-mass spectrometry. These analyses lead to the identification of 604 pod proteins and 965 seed proteins, including 263 proteins distinguishing the pod. The complete data set is publicly available at http://www.cbs.dtu.dk/cgi-bin/lotus/db.cgi, where spots in a reference map are linked to experimental data, such as matched peptides, quantification values, and gene accessions. Identified pod proteins represented enzymes from 85 different metabolic pathways, including storage globulins and a late embryogenesis abundant protein. In contrast to seed maturation, pod maturation was associated with decreasing total protein content, especially proteins involved in protein biosynthesis and photosynthesis. Proteins detected only in pods included three enzymes participating in the urea cycle and four in nitrogen and amino group metabolism, highlighting the importance of nitrogen metabolism during pod development. Additionally, five legume seed proteins previously unassigned in the glutamate metabolism pathway were identified