This paper presents a real-time electrocardiogram (ECG) monitoring system for wearable devices. The system is based on the proposed parallel delta modulator architecture with local maximum point and local minimum point algorithms to detect QRS and PT waves. Therefore, using the proposed system and algorithm, real-time PR and RT intervals, and ST segment measurements can be achieved in long-term wearable ECG recording. The algorithm is tested with the MIT-BIH Arrhythmia Database for QRS complex detection and with the QT Database for the P and T wave detections. The simulation result shows that the algorithm achieves above 99%, 91%, and 98% accuracy in the QRS complex, P wave, and T wave detections, respectively. Experimental results are presented from the system prototype, in which the parallel delta modulator circuits are fabricated in IBM 0.13 $\mu \text{m}$ standard CMOS technology and the algorithms are implemented in a Xilinx Spartan-6 field programmable gate array (FPGA). The parallel delta modulators consume 720 nW at 1 kHz sampling rate with $\pm$0.6 V power supply. The proposed system has the potential to be applied in future long-term wearable ECG recording devices.
Polylactide
[PLA, two enantiomers: poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA)] has been widely applied as biomaterials because
of its biocompatibility, biodegradability, and good mechanical capacity.
However, the chirality of PLA materials has not been intensively explored
yet. In the present study, chiral porous poly(high internal-phase
emulsion)s (polyHIPEs) derived from enantiopure PLAs were successfully
prepared via a HIPE template method. The resulting polyHIPEs show
optical activity. More interestingly, the polyHIPEs demonstrate enantioselective
release capacity, using cinchona alkaloid and naproxen as the model
chiral drugs. Notably, PLLA-based polyHIPE shows enantioselectivity
in both the drug-loading step and drug-releasing step, while PDLA-based
polyHIPE fails. The interesting finding is essentially different from
other chiral polymer materials reported earlier. The cytotoxicity
test demonstrates that all the three types of polyHIPEs, PLLA-, PDLA-,
and PDLLA-based polyHIPE show biocompatibility; however, their different
chirality exerts varying effects on cell growth. Accordingly, special
attention should be devoted to the chirality of PLA when used as biomaterials.
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