The wearable acoustic sensors relieve the discomfort of getting close to a device or speaking loudly, especially in a noisy environment. [4,10,11] These sensors also enable user-friendly smart systems by providing surrounding environmental information through sound monitoring for augmented reality/virtual reality, healthcare, [12] audio surveillance, and noise pollution. [7,13] In this regard, recently, wearable acoustic sensors have been a new research field of electronic skin that has thinness, lightness, bendability, and flexibility like human skin. [8][9][10]12,14] They can serve as part of a second human skin to detect small and noncontact acoustic pressures beyond the human skin's natural function of contact pressure.Wearable acoustic sensors should have sensing performance comparable to human hearing ability. Considering human voices [15] (100-8000 Hz, 40-70 dB SPL ) and ambient sounds of quiet (30 dB SPL ) and noisy (120 dB SPL , e.g., rock concert) environment, [16] the sensors must have sufficient bandwidth (20-10 000 Hz) and acoustic-pressure range (30-120 dB SPL ). In addition, acoustic sensors should be able to compensate for inherent imperfections of human hearing ability and for its degradation due to aging or declining health. For example, human ears are insensitive to harmful low-frequency noises, [17] because the ears perceive the same sound pressure with different volumes depending on the frequency. Human hearing can be damaged by overexposure to loud sounds above 85 dB SPL . [18] Therefore, a wearable acoustic sensor should accurately detect sounds with linear response in ranges of acoustic frequency and pressure to cover human hearing ability.Various wearable and flexible acoustic sensors that exploit piezoelectric, [14,19,20] triboelectric, [8,9,12,21,22] capacitive, [10,23,24] or piezoresistive [25] mechanisms have been developed. However, those wearable sensors have been evaluated using only sensitivity as a performance parameter. [12,14,[19][20][21] High sensitivity is necessary for a good acoustic sensor, but not a sufficient condition. Accurate sound sensing is possible only when the sensor has sufficient bandwidth and dynamic range along with high sensitivity. However, the reported sensors cannot have consistent sensitivity over frequencies of the human-audible Wearable auditory sensors are critical in user-friendly sound-recognition systems for smart human-machine interaction and the Internet of Things. However, previously reported wearable sensors have limited sound-sensing quality as a consequence of a poor frequency response and a narrow acousticpressure range. Here, a skin-attachable acoustic sensor is presented that has higher sensing accuracy in wider auditory field than human ears, with flat frequency response (15-10 000 Hz) and a good range of linearity (29-134 dB SPL ) as well as high conformality to flexible surfaces and human skin. This high sound-sensing quality is achieved by exploiting the low residual stress and high processability of polymer materials in a diaphragm st...

The benzocoumarin dyes fluoresce negligibly in aqueous media but very strongly in cell, whereas representative conventional dyes display contrasting behaviour; the distinct emission behaviour of the fluorophores between in solution,...

A nanoparticle system for systemic delivery of therapeutics is described, which incorporates a means of tracking the fate of the nanocarrier and its residual drug payload in vivo by photoluminescence (PL). Porous silicon nanoparticles (PSiNPs) containing the proapoptotic antimicrobial peptide payload, [KLAKLAK] , are monitored by measurement of the intrinsic PL intensity and the PL lifetime of the nanoparticles. The PL lifetime of the PSiNPs is on the order of microseconds, substantially longer than the nanosecond lifetimes typically exhibited by conventional fluorescent tags or by autofluorescence from cells and tissues; thus, emission from the nanoparticles is readily discerned in the time-resolved PL spectrum. It is found that the luminescence lifetime of the PSiNP host decreases as the nanoparticle dissolves in phosphate-buffered saline solution (37 °C), and this correlates with the extent of release of the peptide payload. The time-resolved PL measurement allows tracking of the in vivo fate of PSiNPs injected (via tail vein) into mice. Clearance of the nanoparticles through the liver, kidneys, and lungs of the animals is observed. The luminescence lifetime of the PSiNPs decreases with increasing residence time in the mice, providing a measure of half-life for degradation of the drug nanocarriers.