3 research outputs found
Integrated Circuits for Programming Flash Memories in Portable Applications
Smart devices such as smart grids, smart home devices, etc. are infrastructure systems that connect the world around us more than before. These devices can communicate with each other and help us manage our environment. This concept is called the Internet of Things (IoT). Not many smart nodes exist that are both low-power and programmable. Floating-gate (FG) transistors could be used to create adaptive sensor nodes by providing programmable bias currents. FG transistors are mostly used in digital applications like Flash memories. However, FG transistors can be used in analog applications, too. Unfortunately, due to the expensive infrastructure required for programming these transistors, they have not been economical to be used in portable applications. In this work, we present low-power approaches to programming FG transistors which make them a good candidate to be employed in future wireless sensor nodes and portable systems. First, we focus on the design of low-power circuits which can be used in programming the FG transistors such as high-voltage charge pumps, low-drop-out regulators, and voltage reference cells. Then, to achieve the goal of reducing the power consumption in programmable sensor nodes and reducing the programming infrastructure, we present a method to program FG transistors using negative voltages. We also present charge-pump structures to generate the necessary negative voltages for programming in this new configuration
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Micron-scale monolithically-integrated ultrasonic wireless sensing motes for physiological monitoring
There has been increasing interest in emerging implantable medical devices (IMDs) for continuous in vivo sensing of physiological signals, including temperature, PH, pressure, oxygen, and glucose, directly at the target locations. Many of these applications can benefit from wireless, miniaturized IMDs that eliminate the percutaneous power cords and facilitate the implantation procedures.
This thesis describes such a device for real-time in vivo monitoring of physiological temperature, such as the monitoring of core body temperature and temperature evaluation during thermal-related therapeutic procedures. Featuring a custom temperature sensor chip with a micron-scale piezoelectric transducer fabricated on top of the chip, the monolithic device, in the form of a mote, measures only 380 μm × 300 μm × 570 μm and weighs only 0.3 mg. The device utilizes ultrasound for wireless powering and communication through the on-chip transducer and achieves aggressive miniaturization through “chip-as-system” integration. The proposed motes were successfully validated in both in vitro experiments with animal tissues and in vivo settings with a mouse model. Compared to the state-of-the-art and equivalent commercial devices, the motes performed comparably or better in a fully-wireless manner while presenting a more compact form factor.
Such extreme miniaturization through monolithic integration enables multiple of these motes to be implanted/injected using minimally invasive surgeries with improved biocompatibility and reduced subject discomfort. This offers new approaches for localized in vivo monitoring of spatially-fine-grained temperature distributions and also provides a platform for sensing other types of physiological parameters