Hand-Powered Inertial Microfluidic Syringe-Tip Centrifuge

Conventional sample preparation techniques require bulky and expensive instruments and are not compatible with next-generation point-of-care diagnostic testing. Here, we report a manually operated syringe-tip inertial microfluidic centrifuge (named i-centrifuge) for high-flow-rate (up to 16 mL/min) cell concentration and experimentally demonstrate its working mechanism and performance. Low-cost polymer films and double-sided tape were used through a rapid nonclean-room process of laser cutting and lamination bonding to construct the key components of the i-centrifuge, which consists of a syringe-tip flow stabilizer and a four-channel paralleled inertial microfluidic concentrator. The unstable liquid flow generated by the manual syringe was regulated and stabilized with the flow stabilizer to power inertial focusing in a four-channel paralleled concentrator. Finally, we successfully used our i-centrifuge for manually operated cell concentration. This i-centrifuge offers the advantages of low device cost, simple hand-powered operation, high-flow-rate processing, and portable device volume. Therefore, it holds potential as a low-cost, portable sample preparation tool for point-of-care diagnostic testing.

PEMURNIAN BIOGAS DARI GAS H2S MENGGUNAKAN KARBON AKTIF DARI BUAH MANGROVE

Biogas layak sebagai bahan bakar mesin pembakaran dalam (internal combustion engine) karena kandungan metana (CH4) yang dimiliki tinggi. Namun, kandungan H2S dalam biogas yang relatif tinggi dapat menyebabkan korosi pada peralatan proses dan berdampak negatif ke lingkungan. Salah satu metode yang dapat dilakukan untuk pemisahan H2S dari biogas adalah dengan adsorpsi menggunakan arang aktif. Penelitian ini dilakukan untuk mengetahui efektivitas pemurnian H2S dalam biogas menggunakan arang aktif dari buah mangrove, serta menentukan konstanta isoterm adsorpsi Freundlich dan Langmuir. Aktivasi adsorben menggunakan larutan KOH 0,5M dan ukuran adsorben pada -3+4 mesh dan -6+8 mesh. Rangkaian alat adsorpsi terdiri dari 3 alat utama yaitu kondenser, flow stabilizer, dan kolom adsorber. Laju alir biogas yang digunakan diatur sebesar 4 liter per menit (lpm) pada suhu ruang dengan tinggi tumpukan adsorben divariasikan pada 6 dan 8 cm. Dari hasil penelitian diperoleh daya adsorpsi maksimum sebesar 0,324 mg/gram dengan efisiensi penjerapan H2S mencapai 83,16% pada ukuran adsorben -6+8 mesh dan tinggi tumpukan 8 cm. Konstanta kesetimbangan adsorpsi H2S dengan metode Langmuir diperoleh sebesar -239,981 dan metode Freundlich sebesar 824,89. Berdasarkan nilai koefisien korelasi (R2), model isoterm Langmuir lebih sesuai untuk adsorpsi H2S dalam biogas dengan arang aktif dari ampas magrove. Kata kunci: Biogas, hidrogen sulfida, buah mangrove, karbon aktif, adsorpsi, adsorben.

Adsorption of Sulphur in Biogas by Activated Carbon Derived From Mangrove Fruits (Rhizopora stylosa) as Solid Residue of Natural Dyes Extraction

Hydrogen sulfide (H2S) is considered as impurity in biogas. H2S could react to form sulfur dioxide (SO2) and sulfuric acid (H2SO4) during the burning process. The corrosive property of these compounds possibly cause damage the power plant system. Overcoming this problem, activated carbon impregnated with KOH has been proven to work very well in adsorbing H2S. On the other hand, mangrove fruits pulp residue from the natural dyes extraction process has not utilized. Mangrove (Rhizopora stylosa) fruits contain about 50% fixed carbon which is possibly made as activated carbon. The purposes of this research were to determine the adsorption efficiency of H2S in biogas using activated carbon derived from mangrove fruits residue and to determine isotherm equilibrium constants for adsorption. The small scale adsorption devices consist of cooler, flow stabilizer, flow regulator, flow meter and column adsorber. At certain flow rate, biogas was sampled in every 10 minutes and then analyzed using portable H2S gas analyzer. Temperatures of biogas entered the adsorption column were in the range of 33-34oC. The optimum biogas flow rate was 4 liter per minute (lpm) for 250 grams (16 cm of height) of activated carbon. We found the adsorption efficiency was decreased by time and still reached 79.6% for 50 minutes contact time. Based on coefficient of correlation value (R2) on isotherm model, Langmuir model is more suitable for the H2S adsorption of biogas in this study. We found the Langmuir equilibrium constant k was 0.033 and maximum adsorption capacity (x/m)max was 0.284 mg/mg.

Flow stabilizer on a syringe tip for hand-powered microfluidic sample injection

We proposed a novel syringe flow-stabilizer for hand-powered, precise, continuous-flow microfluidic sample injection in resource-poor settings.

An Adaptive Control of Machine Table Reciprocation Using a Hydrophone - A Method for Improving the System Efficiency and Reliability -

In order to eliminate unnecessary table-over-travel of a surface grinding machine, the authors previously developed an adaptive table-reciprocation-control system using a hydrophone. The system eliminated the over-travel and reduced grinding time by 20-40%. However, during the stage of the grinding-wheel approach to a workpiece the system did not work. In order to improve the efficiency and reliability of the system, a fluid-flow stabilizer and a new coolant-supply nozzle have been developed and their performances were experimentally investigated. By using these devices, the reciprocation-control system showed its capability even during the stage of the grinding-wheel approach and this ability improved the system efficiency and reliability.