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In this paper we report two different doping strategies to prepare a series of novel HAp:Ln(3+) (Ln = Eu or Tb) nanocrystals with tunable aspect ratios via facile hydrothermal synthetic routes. Adopting a one-pot synthetic strategy, with increasing rare-earth doping dosage, the as-prepared nanocrystals have relatively weak fluorescence intensity, and change from nanorods with lengths of about 150 nm into nanowires with lengths of about 2 μm. Using the synthetic pure HAp nanorods as matrices, they are endowed with bright green or red luminescent properties by doping Tb(3+) or Eu(3+) ions via a second hydrothermal process, and simultaneously retain their original morphologies (diameter 8 nm, length 150 nm). The hydrophobic HAp:Ln(3+) nanorods with strong optical properties are converted into hydrophilic particles with a surfactant (Pluronic F127) and successfully applied to live cell imaging.

Since most of the contact conduction type of heart sound sensors don’t take into account the acoustic signal attenuation problem caused by the heart sound signal transmitting to a sensor whose filling materials’ impedance is different to human soft tissue, the signal-to-noise ratio (SNR) of the heart sound sensors is not very well. Human heart is immersed in blood. If the sensor’s core sensitive element can be immersed in fluid, the attenuation of heart sound signal may be decreased greatly. Inspired by the principle of hydroacoustic signal’s detection, this paper proposes the design of heart sound sensor based on the bionic vector hydrophone. Then theoretical analysis and finite element method (FEM) simulation about the sensor have been carried out. Combined sensitivity with resonant frequency, the optimum dimension of the sensor’s structure has been determined. The sensor’s micro-structure has been fabricated by using Micro-Electro-Mechanical System (MEMS) technology and coupling encapsulated by choosing a kind of medical coupling agent as the filling material. Finally, the performance of the proposed sensor is tested. The fact is that the proposed sensor can work well with either healthy people or patients with heart disease. The obtained data clearly show that: the SNR of the proposed heart sound sensor is superior to 3200-type of 3M Littmann 8.2 dB.