Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Lab Chip. 2011 Feb 21;11(4):645-51. doi: 10.1039/c0lc00447b. Epub 2010 Dec 22.
Precision frequency detection has enabled the suspended microchannel resonator (SMR) to weigh single living cells, single nanoparticles, and adsorbed protein layers in fluid. To date, the SMR resonance frequency has been determined optically, which requires the use of an external laser and photodiode and cannot be easily arrayed for multiplexed measurements. Here we demonstrate the first electronic detection of SMR resonance frequency by fabricating piezoresistive sensors using ion implantation into single crystal silicon resonators. To validate the piezoresistive SMR, buoyant mass histograms of budding yeast cells and a mixture of 1.6, 2.0, 2.5, and 3.0 µm diameter polystyrene beads are measured. For SMRs designed to weigh micron-sized particles and cells, the mass resolution achieved with piezoresistive detection (∼3.4 fg in a 1 kHz bandwidth) is comparable to what can be achieved by the conventional optical-lever detector. Eliminating the need for expensive and delicate optical components will enable new uses for the SMR in both multiplexed and field deployable applications.
精密频率检测使悬浮微通道谐振器（SMR）能够测量单个活细胞、单个纳米粒子以及在流体中吸附的蛋白质层的重量。迄今为止，SMR 共振频率是通过光学方法确定的，这需要使用外部激光和光电二极管，并且不容易进行多路复用测量的阵列化。在这里，我们通过在单晶硅谐振器中进行离子注入来制造压阻式传感器，从而首次实现了 SMR 共振频率的电子检测。为了验证压阻式 SMR，我们测量了出芽酵母细胞的浮力质量直方图以及 1.6、2.0、2.5 和 3.0 µm 直径聚苯乙烯珠的混合物。对于设计用于测量微米级颗粒和细胞重量的 SMR，压阻式检测（在 1 kHz 带宽内约为 3.4 fg）的质量分辨率与传统的光学杠杆检测器相当。消除对昂贵且精密的光学组件的需求，将使 SMR 在多路复用和现场部署应用中得到新的应用。
