Low-Power and ppm-Level Multimolecule Detection by Integration of Self-Heated Metal Nanosheet Sensors

Abstract

H 2 and NH 3 detection with low power consumption was demonstrated by integrated chemiresistive Pt and PtRh nanosheet sensors on glass substrates. The selfheating effects realized low power and local heating of metal nanosheet sensors, enabling the integration of sensors with different operating temperatures. Based on different resistance changes in Pt and PtRh nanosheets toward H 2 and NH 3 , the concentration of each gas was detected from a gas mixture by consuming around 1-mW power. For decreasing the power consumption and further integration of sensors, sensor scaling and pulsed operations were numerically and experimentally studied. In addition to good connectivity of metal nanosheet sensors to large-scale integration (LSI) circuits, improvements of the power consumption by sensor scaling were proven. The pulsed operations required for integrated sensor arrays maintained a sensor response, or a resistance change, of approximately 60%, even when the power consumption was reduced by 20%.

Simultaneous Detection of Mixed-Gas Components by Ionic-Gel Sensors with Multiple Electrodes

“…Even in the parts-per-million-order components in the mixed gas, the fabricated sensor can recognize the gas species as well as the gas concentrations. Note that the estimated gas concentrations of H 2 , NH 3 , and C 2 H 5 OH were in the usual concentration range in human breath. ,, The comparison of sensing properties of our sensor and recently reported sensors are shown in Table . ,− Many papers have reported highly sensitive sensors for single target gas. On the other hand, there have been limited papers on sensors for the simultaneous detection of mixed-gas components.…”

“…To clarify the origin of the dipole, the dipole on the Pt electrode with absorbed NH 3 or chemisorbed hydrogen was calculated using molecular dynamics simulations, as shown in Figure c. The chemisorbed hydrogen was considered as a result of the catalytic reaction of NH 3 on Pt . To our knowledge, a reaction of gas molecules around the IG/electrode interface is still unclear.…”

“…As these chemical species depend on one’s health condition, − health monitoring based on breath sensing has been studied extensively. Several studies have reported the detection of gas species in breath using many types of sensors, such as metal nanosheets, − graphene, − metal oxides, , and ionic liquids (ILs). − Although these gas sensors can detect parts-per-million-order target gas molecules, simultaneous detection of multiple gas components in a mixed gas such as breath is almost impossible by using only a single sensor. To detect multiple components in a mixed gas simultaneously, gas sensor arrays composed of different types of gas sensors are required, because it allows us to utilize an advanced classification scheme.…”

“…To detect multiple components in a mixed gas simultaneously, gas sensor arrays composed of different types of gas sensors are required, because it allows us to utilize an advanced classification scheme. In the reported chemoresistive gas sensor arrays, the size of each gas sensor can be reduced using advanced lithography technology . However, due to high liquidity of the IL, micrometer-scale downsizing of the IL-based sensor is limited by incompatibility with the usual micro- or nanofabrication process.…”

Ultra-low-power switching circuits based on a binary pattern generator with spiking neurons

“…In particular, energy harvesting circuits often involve various types of switching operations 25 , 43 , which could be simply implemented by the binary pattern generator. Low-power sensing could also exploit the advantage of the binary pattern generator; for example, the self-heating gas sensors require fast switching operations to minimize heating power 44 . Finally, it may also be useful for low-power wireless communication especially the one based on the pulse signals, where the intermittent pulse generation is the key to achieve extreme low power on average in the order of nanowatt 45 , 46 .…”