Homoharringtonine In the first test the

In the first test, the chip was covered with Homoharringtonine and thermally ablated once. Then it was thermally ablated again in increments, and resonant frequencies were measured in between increments. Small frequency shifts were measured (~2kHz) for the third mode, with diminishing shifts as the number of increments increased, indicating that an increase in heating time leads to a small reduction in residual content. The result also supports the conclusion that the offset in the linear regression is due to the vaporization of the residual content. In the second test, the chip was placed on the heating element of an oven as it heated up from room temperature to 550°C over 10min. Observations under the microscope showed that this strategy removed nearly all residual content on the biosensor. However, the extreme temperature shorted the piezoelectric layer, preventing further actuation of the biosensor. Therefore, a maximum temperature between 370 and 550°C may be more suitable for thermal ablation of devices featuring an aluminum nitride piezoelectric film. This could be achieved with a more powerful hot plate. In the third test, instead of gradually heating up the chip on the hot plate, the chip at room temperature was placed on the hot plate at maximum temperature and left there for 1min. This restored the biosensor\'s third resonant frequency to 104±7% of its initial value, using a calculated average over three tests. While this strategy shows promise for the present biosensor, such an extreme temperature rise may change material properties in certain biosensor designs.
Conclusion The surface of a silicon biosensor can be effectively regenerated by placing the chip on a hot plate and thermally ablating bound biological material at 370°C. Images show that most of the cellular content of bound E. coli cells is removed from the sensing surface. Measurements and analysis further reveal that the biosensor\'s resonant frequencies are restored to 82% of their initial value. The remaining 18% of the resonant frequencies shift is attributable to residual cellular content. This residual content may be further removed, without affecting biosensor performance, by performing thermal ablation using a higher temperature rise or a higher temperature. Nonetheless, this convenient regeneration technique is of interest for researchers developing and testing biosensors made of silicon or other heat resistant materials.
Acknowledgments The authors would like to thank NSERC (327081) for funding support and CMC Microsystems for fabrication service support.
Introduction Due to its high nutritional value and distinctive flavor with a tender and delicate texture, the consumer demand for shrimp is enormous. In USA, the volume of imports of shrimp was about 1120 million pounds in 2013 [1]. In China, the volume of shrimp culture was about 5314 million pounds in 2011 [2]. Shrimp undergoes bacterial contamination and enzymatic activity during transportation and storage [3–10], the ingredients like protein, fat and carbohydrates are decomposed into ammonia, hydrogen sulfide, ethyl mercaptan, aldehydes, aldehyde acids, alcohols, ketones, aldehydes, and carboxylic acid gases [3,6]. These chemical compounds give rise to off-flavors and other unpleasant characteristic [4–7], the freshness of shrimp degrades. Consumption of spoilage shrimp could cause serious health hazards [3,5]. It is important to assess the freshness of shrimp. The spoilage shrimp gives off unpleasant odors. If the shrimp odor is detected, its freshness could be assessed. A simple, quick technology to inspect food odor is electronic nose. Electronic nose is a simulation of biological functions to identify some simple or complex odor [11,12]. The electronic nose is used as a non-destructive method for food quality detection [13–17], such as classifying stored grain, analyzing water and wastewater, monitoring roasting process, testing freshness of fish and fruit, controlling the manufacture of cheese, sausage, beer, and bread, and detecting bacterial growth in meat and vegetables.