Battery-operated portable PCR system with enhanced stability of Pt RTD.

This paper reports an outdoor-use polymerase chain reaction (PCR) technology in which stability of resistance temperature detectors (RTDs) is remarkably improved. A thin-film RTD made of non-annealed Pt shows accuracy degradation because the resistance of the RTD tends to decrease during the PCR operation. Thus, the annealing process is applied to the Pt RTD to improve the stability, which is a prerequisite to the accurate measurement of the absolute temperature. Both heaters and the RTD are fabricated on a thin quartz substrate whose melting temperature is high enough for annealing. The performances in the PCR time and power consumption are enhanced by reducing the size of the heater chips with no degradation in the temperature uniformity. A spring-loaded electrode is employed to simplify the procedure of electrical connection to the thermal controller and loading/unloading of the PCR chip. The contact area of the electrical connection is so small that the conductive thermal resistance increases; thereby small heat dissipation can be exploited for low-power operation. The stability of the RTD is experimentally confirmed in terms of resistance variation over repeated PCR operations (four times). The least variation of 0.005%, which corresponds to a negligible temperature variation of 0.038 °C for the PCR, is achieved from the RTD annealed for 5 min at 450 °C. The gel-electrophoresis result indicates that the PCR performance of the proposed system using a film-type PCR chip is comparable to that of a conventional system using a vial tube despite its low power consumption.

Portable low-power thermal cycler with dual thin-film Pt heaters for a polymeric PCR chip.

Polymerase chain reaction (PCR) has been widely used for major definite diagnostic tool, but very limited its place used only indoor such as hospital or diagnosis lab. For the rapid on-site detection of pathogen in an outdoor environment, a low-power cordless polymerase chain reaction (PCR) thermal cycler is crucial module. At this point of view, we proposed a low-power PCR thermal cycler that could be operated in an outdoor anywhere. The disposable PCR chip was made of a polymeric (PI/PET) film to reduce the thermal mass. A dual arrangement of the Pt heaters, which were positioned on the top and bottom of the PCR chip, improved the temperature uniformity. The temperature sensor, which was made of the same material as the heater, utilized the temperature dependence of the Pt resistor to ensure simple fabrication of the temperature sensor. Cooling the PCR chip using dual blower fans enabled thermal cycling to operate with a lower power than that of a Peltier element with a high power consumption. The PCR components were electrically connected to a control module that could be operated with a Li-ion battery (12 V), and the PCR conditions (temperature, time, cycle, etc.) were inputted on a touch screen. For 30 PCR cycles, the accumulated power consumption of heating and cooling was 7.3 Wh, which is easily available from a compact battery. Escherichia coli genomic DNA (510 bp) was amplified using the proposed PCR thermal cycler and the disposable PCR chip. A similar DNA amplification capability was confirmed using the proposed portable and low-power thermal cycler compared with a conventional thermal cycler.

Imaging of the Finger Vein and Blood Flow for Anti-Spoofing Authentication Using a Laser and a MEMS Scanner.

A new authentication method employing a laser and a scanner is proposed to improve image contrast of the finger vein and to extract blood flow pattern for liveness detection. A micromirror reflects a laser beam and performs a uniform raster scan. Transmissive vein images were obtained, and compared with those of an LED. Blood flow patterns were also obtained based on speckle images in perfusion and occlusion. Curvature ratios of the finger vein and blood flow intensities were found to be nearly constant, regardless of the vein size, which validated the high repeatability of this scheme for identity authentication with anti-spoofing.

Ex vivo characterization of age-associated impedance changes of single vascular endothelial cells using micro electrical impedance spectroscopy with a cell trap.

We aimed to characterize aging of single vascular endothelial cells, which are indicators of senescence, using micro electrical impedance spectroscopy (µEIS) for the first time. The proposed µEIS was equipped with two barriers under the membrane actuator near the sensing electrodes, increasing its cell-trapping capability and minimizing the interference between the target cell and subsequent cells. The cell-trapping capability in µEIS with barriers was considerably improved (90%) with a capture time of 5 s or less, compared to µEIS without barriers (30%). Cells were extracted from transgenic zebrafish to minimize an initial discrepancy originating from genetic differences. In order to estimate useful parameters, cytoplasm resistance and membrane capacitance were estimated by fitting an electrical equivalent circuit to the data of ex vivo sensor output. The estimated cytoplasm resistance and membrane capacitance in the younger vascular endothelial cells were 20.16 ± 0.79 kΩ and 17.46 ± 0.76 pF, respectively, whereas those in the older cells were 17.81 ± 0.98 kΩ and 20.08 ± 1.38 pF, respectively. Discrimination of each group with different aging showed statistical significance in terms of cytoplasm resistance (p < 0.001) and membrane capacitance (p < 0.001). Considering both of the sensor and cellular level, the optimal frequency was determined as 1 MHz at which the electrical impedance of each group was clearly discriminated (p < 0.001).

A new posture-correcting system using a vector angle model for preventing forward head posture.

In modern society many people are afflicted with muscle pain in the neck and shoulders mainly caused by incorrect posture. The number of patients having neck pain is increasing as usage of digital devices becomes more frequent. If patients could be notified how inappropriate their postures are in real time, the number of patients could be lower. Unfortunately, there is no digitized standard way of diagnosis for forward head posture. This study applies a concept based on a vector related to two angles which are acquired from the neck and the head, so that a device can diagnose the posture by measuring and analysing the angles. To obtain the vector, integral calculations of displacement of the head are needed. As a result, with this device, patients' faulty posture can be easily detected.