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This paper reports a global digital controller for multi-channel high density micro-stimulator applications. By centralizing the essential functions including stimulation timing controls, tissue-electrode impedance (TEI) monitoring and power supply modulation in the global digital controller (GDC), digital blocks in the local electrode driver channels (LEDCs) can be greatly simplified, resulting in compact electrode drivers suitable for high density intracellular stimulations. Based on the proposed column-parallel row-scanning (CPRS) stimulator topology, the 5-wire global control ensures customized per channel stimulation with minimal interfacing overhead. A 4-column GDC stimulator prototype is fabricated in a 0.18 µm CMOS process. It features flexible stimulation with a power consumption of 18 µW/column while enabling global power-supply modulation and real-time TEI monitoring for improved stimulation efficiency and safety. [ABSTRACT FROM AUTHOR]

Highlights • Achieving the reference hybridization equilibrium with >13 times faster reaction rate. • Rapid mixing with wide range of DNA concentrations (from 1 to 10 μM). • On-chip isothermal DNA hybridization within ±0.1°C. Abstract DNA hybridization kinetics has been playing a critical role in molecular diagnostics for binding discrimination, but its study on digital microfluidic (DMF) systems is ultimately restrained by the laminar flow condition. The kinetic mixing technique is widely employed to ensure a fast reaction rate, but poses intrinsic risk in cross contamination and exhibits instable fluorescence intensity during the droplet transportation. While the electrothermal technique can provide stationary droplet mixing through the established thermal gradient within the hybridization solution, the significant increase in the droplet temperature will inevitably undermine the hybridization equilibrium and jeopardize the binding discrimination. To enhance the hybridization efficiency while ensuring a stable droplet temperature (within ±0.1℃), this paper presents a DMF platform that can perform isothermal hydrodynamic-flow-enhanced droplet mixing. Specifically, with a single electrode, droplet-boundary oscillation under a slow AC actuation is studied for improving the reaction rate. The dependencies between the mixing efficiency and the actuation voltage, actuation frequency and the spacer thickness are also systematically studied. Reliable mixing efficiency improvement is further validated over a wide range of solute concentrations. The results from real-time on-chip DNA hybridization kinetics with stationary droplets using the complete sandwiched DMF system shows that the proposed rapid mixer can achieve the same hybridization equilibrium with >13 times faster reaction rate when compared to the reference one through pure diffusion, while preventing biased hybridization kinetics as demonstrated in the electrothermal technique. [ABSTRACT FROM AUTHOR]

This paper proposes a precision bandgap voltage reference (BGR) with a segmented curvature compensation technique, demonstrating both small temperature coefficient (TC) and low power consumption. By segmenting the output voltage of a conventional first-order BGR over a wide temperature range and implementing compensation for each segment, the output reference voltage can be systematically aligned to an identical voltage level, effectively reducing the achievable TC. An additional circuit consists of comparators, logic gates, switches and current mirrors is proposed to achieve this compensation scheme, which also optimizes the overall BGR power consumption. Implemented and simulated in a standard 65 ​nm CMOS process, the proposed BGR achieves an average output of 496.17 ​mV and a TC of 1.08 ​ppm/°C from −40 ​°C to 125 ​°C. It consumes a current of 765 ​nA under a 1.2 ​V supply while exhibiting a line regulation of 0.725%/V with V DD from 1.0 to 1.8 ​V ​at 27 ​°C. [ABSTRACT FROM AUTHOR]