Nedelcu Stefan, Thodkar Kishan, Hierold Christofer
Micro- and Nanosystems, Department of Mechanical and Process Engineering, ETH Zurich, Tannenstrasse 3, 8092 Zurich, Switzerland.
Microsyst Nanoeng. 2022 Jan 14;8:10. doi: 10.1038/s41378-021-00343-1. eCollection 2022.
Customizable, portable, battery-operated, wireless platforms for interfacing high-sensitivity nanoscale sensors are a means to improve spatiotemporal measurement coverage of physical parameters. Such a platform can enable the expansion of IoT for environmental and lifestyle applications. Here we report a platform capable of acquiring currents ranging from 1.5 nA to 7.2 µA full-scale with 20-bit resolution and variable sampling rates of up to 3.125 kSPS. In addition, it features a bipolar voltage programmable in the range of -10 V to +5 V with a 3.65 mV resolution. A Finite State Machine steers the system by executing a set of embedded functions. The FSM allows for dynamic, customized adjustments of the nanosensor bias, including elevated bias schemes for self-heating, measurement range, bandwidth, sampling rate, and measurement time intervals. Furthermore, it enables data logging on external memory (SD card) and data transmission over a Bluetooth low energy connection. The average power consumption of the platform is 64.5 mW for a measurement protocol of three samples per second, including a BLE advertisement of a 0 dBm transmission power. A state-of-the-art (SoA) application of the platform performance using a CNT nanosensor, exposed to NO gas concentrations from 200 ppb down to 1 ppb, has been demonstrated. Although sensor signals are measured for NO concentrations of 1 ppb, the 3 limit of detection (LOD) of 23 ppb is determined (1: 7 ppb) in slope detection mode, including the sensor signal variations in repeated measurements. The platform's wide current range and high versatility make it suitable for signal acquisition from resistive nanosensors such as silicon nanowires, carbon nanotubes, graphene, and other 2D materials. Along with its overall low power consumption, the proposed platform is highly suitable for various sensing applications within the context of IoT.
用于连接高灵敏度纳米级传感器的可定制、便携式、电池供电的无线平台是提高物理参数时空测量覆盖率的一种手段。这样的平台能够推动物联网在环境和生活方式应用方面的扩展。在此，我们报告一种平台，它能够以20位分辨率和高达3.125 kSPS的可变采样率采集满量程范围从1.5 nA至7.2 µA的电流。此外，它具有在-10 V至+5 V范围内可编程的双极电压，分辨率为3.65 mV。有限状态机通过执行一组嵌入式功能来控制系统。该有限状态机允许对纳米传感器偏置进行动态、定制化调整，包括用于自热的升高偏置方案、测量范围、带宽、采样率和测量时间间隔。此外，它还能将数据记录到外部存储器（SD卡）并通过低功耗蓝牙连接进行数据传输。对于每秒三个样本的测量协议，该平台的平均功耗为64.5 mW，包括发射功率为0 dBm的低功耗蓝牙广告。已经展示了该平台性能在使用碳纳米管纳米传感器的最先进（SoA）应用，该传感器暴露于浓度范围从200 ppb降至1 ppb的一氧化氮气体中。尽管针对1 ppb一氧化氮浓度测量了传感器信号，但在斜率检测模式下确定的检测限（LOD）为23 ppb（1:7 ppb），包括重复测量中的传感器信号变化。该平台宽电流范围和高通用性使其适用于从诸如硅纳米线、碳纳米管、石墨烯和其他二维材料等电阻式纳米传感器采集信号。连同其总体低功耗，所提出的平台非常适合物联网背景下的各种传感应用。
