One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20ms, indicating a very high efficiency of pulse driving.

The influence of ultrasonication pretreatment on fermentative bioenergy [ethanol/hydrogen (H₂)] production from a newly isolated microalgae biomass (Scenedesmus obliquusYSW15) was investigated. S. obliquusYSW15 biomass was sonicated for 0 min (control), 5 min (short-term treatment), 15 and 60 min (long-term treatment), which caused different states of cell lysis for microbial fermentation. Long-term sonication significantly damaged the microalgal cell integrity, which subsequently enhanced the bioenergy production. The accumulative bioenergy (ethanol/hydrogen) production after long-term sonication was almost 7 times higher than that after short-term treatment or the control. The optimal ratio of microalgal biomass to anaerobic inoculum for higher bioenergy production was 1 : 1. Microscopic analyses with an energy-filtering transmission electron microscope (EF-TEM) and an atomic force microscope (AFM) collectively indicated that cells were significantly damaged during sonication and that the carbohydrates diffused out of the microalgae interiors and accumulated on the microalgae surfaces and/or within the periplasm, which led to enhanced bioaccessibility and bioavailability of the biomass. These results demonstrate that ultrasonication is an effective pretreatment method for enhancing the fermentative bioenergy production from microalgal biomass.