Miniaturization of PCR Machine

The polymerase chain reaction (PCR) is a technique defined for copying specific DNA sequences. The three basic steps in that process - splitting a DNA template into its two single strands (called denaturation); adding short segments of complementary DNA called primers to initiate replication of a chosen DNA sequence (annealing); and adding DNA polymerase to synthesis the complementary strand (called extension) - are repeated again and again to amplify the sequence. Each of these steps occurs optimally at a different temperature, so heating and cooling is carried out with an instrument called a thermal cycler. Better than the conventional big size PCR here we have designed a circuit which is capable of performing fast temperature rise and fall and that is within small region. This design supports the easy transportability of the machine because of its smaller size with very low design cost

Smartphone-powered, ultrasensitive, and selective, portable and stable multi-analyte chemiresistive immunosensing platform with PPY/COOH-MWCNT as bioelectrical transducer: Towards point-of-care TBI diagnosis

Traumatic Brain Injury, one of the significant causes of mortality and morbidity, affects worldwide and continues to be a diagnostic challenge. The most desirable and partially met clinical need is to simultaneously detect the disease-specific-biomarkers in a broad range of readily available body fluids on a single platform with a rapid, low-cost, ultrasensitive and selective device. Towards this, an array of interdigitated microelectrodes was fabricated on commercially existing low-cost single-side copper cladded printed-circuit-board substrate followed by the bioelectrodes preparation through covalent immobilization of brain injury specific biomarkers on carboxylic functionalized multi-walled carbon nanotubes embedded polypyrrole nanocomposite modified interdigitated microelectrodes. Subsequently, the immunological binding events were transduced as the normalized change in bioelectrode resistance with and without the target analyte via current-voltage analysis. As proof of concept, current-voltage responses were primarily recorded using a conventional probe station, and later, a portable handheld-electronic-readout was developed for the point-of-care application. The data compilation and analysis were carried out using the in-house developed android-based mobile app. Notably, the smartphone powered the readout through a PL-2303 serial connector, avoiding integrating power sources with the readout. Further, this technology can be adapted to other point-of-care biosensing applications

Fabrication of micro separation column for miniaturized gas chromatography system

The emphasis of this work is on the fabrication of a micro separation column for applicaton in miniaturized gas chromatography system. The micro column was made by microchannels fabricated on the silicon wafer and sealed with a glass lid. The microchannels were fabricated by wet etching process and the channels were of length 2m , width 200 μm and depth 100 μm. The channels were closed by sealing with Pyrex glass. Silicide bonding was done for the bonding of silicon with Pyrex glass. Ti was used as an intermediate layer and bonded at a temperature of 377 ◦C and a force of 1kN. During bonding Ti forms an alloy with silicon and forms Titanium silicide and this helps to bond the glass wafer with silicom wafer with microchannels etched on it

Measurement and modeling of pulsatile flow in microchannel

An experimental study of pulsatile flow in microchannel is reported in this paper. Such a study is important because time-varying flows are frequently encountered in microdevices. The hydraulic diameter of the microchannel is 144 μm and deionized water is the working fluid. The pressure drop across the microchannel as a function of time is recorded, from which the average and r.m.s. pressure drops are obtained. The experiments have been performed in the quasi-steady flow regime for a wide range of flow rate, frequency of pulsations, and duty cycle. The results suggest that the pressure with pulsations lies between the minimum and maximum steady state pressure values. The average pressure drop with pulsation is approximately linear with respect to the flow rate. The theoretical expression for pressure has also been derived wherever possible and the experimental data is found to lie below the corresponding theoretical values. The difference with respect to the theoretical value increases with an increase in frequency and a decrease in flow rate, with a maximum difference of 32.7%. This is attributed to the small size of the microchannel. An increase in frequency of square waveform leads to a larger reduction in pressure drop as compared to rectangular waveform, irrespective of the duty cycle. The results can be interpreted with the help of a first-order model proposed here; the model results are found to compare well against the experimental results. A correlation for friction factor in terms of the other non-dimensional governing parameters is also proposed. Experimental study of mass-driven pulsatile flow in microchannel is being conducted for the first time at these scales and the results are of both fundamental and practical importance

Analysis of Impact of Transformer Coupled Input Matching on Concurrent Dual-Band Low Noise Amplifier

Emerging advancements in telecommunication system need robust radio devices which can capable of working multiple frequency bands seamlessly. In any Radio Frequency (RF) receiver architecture, Low Noise Amplifier (LNA) is the mandatory front-end part in which takes place in between antenna and mixer. To support multiple frequency bands with single hardware, concurrent LNA is the more preferred topologies among others. As LNA is the very front end level of receiver, Input matching, Noise Figure (NF) and gain are the major performance parameters to be concerned. In this work, the impact of transformer coupled input matching on concurrent dual-band LNA is analyzed and verified. A concurrent LNA with concurrent matching without transformer coupling is used for comparison. A transformer coupled input matching is proposed for tunable concurrent dual-band LNA. All the circuits are implemented in UMC 180nm CMOS technology, and simulated using Cadence SpectreRF simulation tool

Three-Dimensional Numerical Study of Conjugate Heat Transfer in Diverging Microchannel

Increase in applications of varying cross sectional area microchannels in microdevices has provided the need to understand fluid flow and heat transfer through such flow passages. This study focuses on conjugate heat transfer study through a diverging microchannel. Three-dimensional numerical simulations are performed using commercially available package. Diverging microchannels with different geometrical configurations (i.e. varying angle: 1-8°, depth: 86-200 μm, solid-to- fluid thickness ratio: 1.5-4) are employed for this purpose. Simulations are carried out for varying mass flow rate (3.3 x 10 –5 -8.3 x 10 –5 kg/s) and heat flux (2.4-9.6 W/cm 2 ) conditions. Heat distribution along the flow direction is studied to understand the effect of wall conduction. Wall conduction number ( M ) varies from 0.006 to 0.024 for the range of parameters selected in the study. Wall conduction is observed to be a direct function of depth and solid-to-fluid thickness ratio, and varies inversely with angle of diverging microchannel. It is observed that the area variation and wall conduction contribute separately towards redistribution of the supplied heat flux. This leads to reduced temperature gradients in diverging microchannel. The results presented in this work will be useful for designing future microdevices involving heating or coolin

Efficient adaptive switch design for charge pumps in micro-scale energy harvesting

The performance of Micro-scale energy harvesting unit depends on the efficient design of charge-pump. Optimization of the dimension of MOSFET switches in charge pump is one of the techniques to improve the efficiency. In this work, a new optimization technique for transistor sizing and a concept of reconfigurable adaptive switches has been introduced to maximize the extracted power. A control unit is designed for adaptive reconfiguration of the switches. These proposed techniques are validated for linear charge-pump topology in UMC 180nm technology. Combined effect of size optimization of switch along with reconfigurable switch offers an improvement up to 23.5% in the net harvested power with 6% less silicon area

Highly sensitive and ultra-fast responsive ammonia gas sensor based on 2D ZnO nanoflakes

Detecting ammonia in ambient air with high sensitivity and ultra-fast responsivity is crucial given its implications on human health. The response of such sensors should also be reversible to use them for continuous monitoring. Herein, we report a reversible ammonia (NH3) sensor based on 2D ZnO nanoflakes at 250 °C. The sensor exhibited a maximum response of 80% and sub-15 s response and recovery times upon exposure of 0.6–3 ppm NH3. Further, we formulated and corrected the baseline drift with a simple and straightforward baseline manipulation method. The excellent response of the sensor indicates the feasibility of using it in diverse applications where high sensitivity and rapid response are crucial. © 202

Design, Process Development and Fabrication of SU-8 based CMOS Compatible Capacitive MEMS Platform for Bio-sensing Applications

Bio sensors are integrated devices which could provide information about the composition of Biological samples (semi) quantitatively. The key element of Bio sensors are their transducers which are usually Micro or Nano scale structures with Biological recognition elements as part of them. Realization of a practical and usable Bio sensor involves a wide range of interdisciplinary activities. The emerging interdisciplinary fields of Nanotechnology and Nano fabrication has helped the heterogeneous integration of Biology with Engineering systems which was not possible earlier

A Smartphone-based High Sensitivity Impedance Readout Circuit for Milk Adulteration

The proposed work develops a lab-on-chip platform to detect the milk adulteration which exploit the smartphone to overcome the external battery usage and calibration. To have a low cost and convenient platform for sensing, the interface circuit is powered through the smartphone and calibration is done through the customized built Application using Android studio and Arduino IDE.A great accuracy of 0.1Ω change is achieved by this work. The OTA designed has a high GBW of 110 MHz, high gain of 90 dB and very low noise floor .Apart from this, a wide range resistive readout circuit is also implemented which could sense the resistance ranging from 10KΩ-1GΩ.The whole design is analyzed in TSMC 0.18µ technology