A thickness longitudinal mode (TLM) thin film bulk acoustic resonator biosensor is demonstrated to operate in water with a high quality-factor, Q. This is achieved using a layer of carbon nanotubes (CNTs) on top of the resonator which has a significantly different acoustic impedance to either the resonator or liquid whilst being susceptible to the binding of biological molecules. This allows the resonance to be decoupled from direct energy loss into the liquid, although still retaining mass sensitivity. AlN solidly mounted resonators (SMRs) having a thickness shear mode (TSM) at 1.1 GHz and TLM at 1.9 GHz are fabricated. CNTs with different forest densities are grown by chemical vapor deposition on the active area with Fe as the catalyst and resulting devices are compared. High forest density CNTs are shown to acoustically decouple the SMRs from the water and in-liquid TLM Q values higher than 150 are recorded even exceeding TSM SMRs without CNTs. The TLM Q in water is remarkably improved from 3 to 160 for the first time by dense CNT forests, rendering the large-scale fabrication of TLM SMRs for liquid-phase sensing applications possible. Despite this partial isolation, SMRs with CNT forests ∼15 μm tall can still detect binding of bovine serum albumin.

厚度纵向模式（TLM）薄膜体声波谐振器生物传感器被证明可以在水中以高品质因数Q工作。这是通过在谐振器顶部使用一层碳纳米管（CNT）来实现的，该碳纳米管对谐振器或液体具有明显不同的声阻抗，同时容易受到生物分子的结合。尽管仍保持质量灵敏度，这可以使共振与直接能量损失解耦到液体中。制作具有在1.1 GHz的厚度剪切模式（TSM）和在1.9 GHz的TLM的AlN固体安装谐振器（SMR）。以Fe为催化剂，通过化学气相沉积在活性区域上生长出具有不同森林密度的CNT，并比较了所得器件。高森林密度的碳纳米管显示出可以将SMR与水和液体中的TLM Q分离开甚至超过了不含CNT的TSM SMR时，记录的值也高于150。密集的CNT森林首次将水中的TLM Q从3显着提高到160，使得大规模生产用于液相传感应用的TLM SMR成为可能。尽管进行了部分隔离，但具有约15μm高的CNT林的SMR仍可以检测到牛血清白蛋白的结合。