Department of Electronic and Electrical Engineering, and Sungkyunkwan University Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
Nanotechnology. 2011 Nov 4;22(44):445501. doi: 10.1088/0957-4484/22/44/445501. Epub 2011 Oct 11.
We fabricated nanoparticle-based gas through in situ ac dielectrophoretical assembling of drop-coated SnO(2) nanoparticles to bridge the gap between electrodes with high aspect ratio. While the conventional dielectrophoresis (DEP) adopts a microfluidic system for continuous flow of the solution during the process, we just drop-coated a small amount of solution onto the electrodes and executed in situ DEP for a very short time. This is a very simple, cost-effective, time-saving, and highly reproducible process. We fixed the duration time and applied voltage for the DEP at 1 s and 1 V respectively and changed the frequencies from 1 up to 500 kHz. I-V characteristics of the samples were checked and it was found that DEP samples fabricated at 1 s, 1 V and 150 kHz conditions showed considerably higher connectivity of the nanoparticles. This can be attributed to the excellent step coverage achieved by ac DEP under those conditions. The devices drop-coated and dielectrophoretically assembled at other ac frequency conditions showed poor connectivity. Hydrogen gas sensing properties of the sensors fabricated under 1 s, 1 V and 150 kHz conditions were checked by flowing through 160 ppm H(2). The sensitivity reaches a maximum value of ~ 700% at 350 °C. The response time is ~ 200 s at 350 °C.
我们通过原位交流电介电泳组装滴涂的 SnO(2)纳米粒子来制造纳米粒子气体，从而桥接高纵横比电极之间的间隙。虽然传统的介电泳（DEP）在溶液流经微流控系统的过程中采用连续流动，但我们只在电极上滴涂少量溶液，并在非常短的时间内执行原位 DEP。这是一个非常简单、经济高效、节省时间且高度可重复的过程。我们将 DEP 的持续时间和施加电压分别固定在 1 s 和 1 V，并将频率从 1 增加到 500 kHz。我们检查了样品的 I-V 特性，发现在 1 s、1 V 和 150 kHz 条件下制造的 DEP 样品表现出相当高的纳米粒子连通性。这可以归因于在这些条件下交流电介电泳实现的优异阶梯覆盖率。在其他交流电频率条件下滴涂和电介质组装的器件表现出较差的连通性。在 1 s、1 V 和 150 kHz 条件下制造的传感器的氢气传感性能通过流经 160 ppm H(2)进行检查。在 350°C 时，灵敏度达到约 700%的最大值。在 350°C 时，响应时间约为 200 s。
