This paper reports an implantable microsystem capable of recording neural activity simultaneously on 64 channels, wirelessly transmitting spike occurrences to an external interface. The microsystem also allows the user to examine the spike waveforms on any channel with 8 bit resolution. Signals are amplified by 60 dB with a programmable bandwidth from < 100 Hz to 10 kHz. The input-referred noise is 8 ?Vrms. The channel scan rate for spike detection is 62.5 kS/sec using a 2 MHz clock. The system dissipates 14.4 mW at 1.8 V, weighs 275 mg, and measures 1.4 cm 1.55 cm.

An Implantable 64-Channel Wireless Microsystem for Single-Unit Neural Recording

An optical interference display panel is disclosed that has a substrate, an optical interference reflection structure, and an opaque protection structure. The optical interference reflection structure has many color-changeable pixels and is formed on the substrate. The opaque protection structure is adhered and fixed onto the substrate with an adhesive and encloses the optical interference reflection structure between the substrate and the opaque protection structure. The opaque protection structure blocks and/or absorbs light, and light is thus not emitted outward by passing through defects in the optical interference reflection structure. Moreover, the opaque protection structure and the adhesive also prevent the optical interference reflection structure from being damaged by an external environment.

Optical interference display panel

We have developed a single-wafer vacuum encapsulation for microelectromechanical systems (MEMS), using a thick (20-mum) polysilicon encapsulation to package micromechanical resonators in a pressure 600 cycles of -50 to 80degC, and no measurable change in cavity pressure was seen. We have also performed accelerated leakage tests by driving hydrogen gas in and out of the encapsulation at elevated temperature. Two results have come from these hydrogen diffusion tests. First, hydrogen diffusion rates through the encapsulation at temperatures 300-400degC have been determined. Second, the package was shown to withstand multiple temperature cycles between room and 300-400degC without showing any adverse affects. The high robustness and stability of the encapsulation can be attributed to the clean, high-temperature environment during the sealing process

/pdf/long-term-and-accelerated-life-testing-of-a-novel-single-3ylhgpsftp.pdf

Long-Term and Accelerated Life Testing of a Novel Single-Wafer Vacuum Encapsulation for MEMS Resonators

https://www.repository.cam.ac.uk/bitstream/handle/1810/246007/Coriolis-draft-paper-V8.1-FMI-Larger-Fonts.pdf?sequence=1

Coriolis flowmeters: a review of developments over the past 20 years, and an assessment of the state of the art and likely future directions

A first electrode and a sacrificial layer are sequentially formed on a substrate, and then first openings for forming supports inside are formed in the first electrode and the sacrificial layer. The supports are formed in the first openings, and then a second electrode is formed on the sacrificial layer and the supports, thus forming a micro electro mechanical system structure. Afterward, an adhesive is used to adhere and fix a protection structure to the substrate for forming a chamber to enclose the micro electro mechanical system structure, and at least one second opening is preserved on sidewalls of the chamber. A release etch process is subsequently employed to remove the sacrificial layer through the second opening in order to form cavities in an optical interference reflection structure. Finally, the second opening is closed to seal the optical interference reflection structure between the substrate and the protection structure.

Optical interference display panel and manufacturing method thereof

A new approach to vacuum packaging of micro-machined resonant, tunneling, and display devices is covered in this paper. A multi-layer, thin-film getter, called a NanoGetter, which is particle free and does not increase the chip size of the microsystem has been developed and integrated into conventional wafer-to-wafer bonding processes. Hermetic electrical feedthroughs are also provided as part of this total-solution technology. Experimental data taken with silicon resonators is presented in which Q values in excess of 21,000 have been obtained. Applications for this technology include gyroscopes, accelerometers, displays, flow sensors, density meters, infrared (IR) sensors, microvacuum tubes, radio frequency microelectromechanical systems (RF-MEMS) and pressure sensors.

Chip-level vacuum packaging of micromachines using NanoGetters

A new microfluidic system for measuring the mass flow rate, dose, chemical concentration, fluid density, specific gravity and temperature has been developed. Vacuum packaged, resonating silicon microtubes are employed to form both a Coriolis mass flow and density sensor. The micro Coriolis mass flow sensor has 10 times the resolution of the best commercially available macro Coriolis mass flow sensors. An onchip temperature sensor (RTD) has been added to the microchip, enabling accurate fluid temperature monitoring. At constant temperature the density resolution/or output stability approaches 1 over 1 million (6 digits) in the new system. Also a new method of chip-level gettering was developed to achieve the milliTorr pressures needed for adequate resonator signal quality for the vacuum packaged microsensors. Applications for both mass flow measurements and density sensing are discussed.

/pdf/coriolis-mass-flow-density-and-temperature-sensing-with-a-1qj850hj0n.pdf

D.R. Sparks

Papers

Chip-level vacuum packaging of micromachines using NanoGetters

Coriolis mass flow, density and temperature sensing with a single vaccum sealed mems chip