Yusmeeraz Yusof

A Flexible Optical Sensor for Microalbuminuria Spectroscopy

Zarina Mohd Noh*, Abdul Rahman Ramli, Marsyita Hanafi, M Iqbal Saripan, Ridza Azri Ramlee 1,2,3,4 Department of Computer and Communication Systems Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia 1,5 Fakulti Kejuruteraan Elektronik dan Kejuruteraan Komputer, Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya, 75450 Durian Tunggal, Melaka, Malaysia

Controlled defect on multilayer graphene surface by oxygen plasma

The study pertaining defect fabrication of graphene has gained interest nowadays. To date, the fabrication of the defect using reactive ion etching on the oxygen flow rate has not been adequately studied. In this work, fabrication defect on multilayer graphene using reactive ion etching at 30 sccm and 50 sccm oxygen flow rates as a controlled parameter. The other parameters such as pressure, exposure time and power are set as well. The resistance of the exposed multilayer graphene devices at 30 sccm and 50 sccm are respectively 38 and 49 times higher than the non-exposed device. The increased oxygen flow rate in the reactive ion etching deteriorates the crystalline quality of the multilayer graphene thus declines its function as a device. It is suggested that only low oxygen flow rate is to be used to fabricate small amount of defect for the controlled defect purposes.

Ultra sensitive CMOS biosensor array for label free DNA detection: Circuit design consideration

Electrical biosensors are one strategy being explored for the development of a rapid point-of-care and onsite DNA testing tools since this technology is amenable to miniaturization, can be accurate and highly sensitive with simple instrumentation, and relatively inexpensive. A label free and fully integrated semiconductor sensor array based on differential charge-based capacitance measurement for DNA sensing is presented. The 4 × 4 sensor array circuit has been designed using a 2-poly 2-metal 1.2 μm CMOS process from ON Semiconductor. Each sensor features an integrated microelectrode of 16 μm2. The linear sensitivity is 3 mV/fF for the target input capacitance range of 1 to 103 fF. An array-clock controller scheme to selectively activate the array cell and capacitance-to-voltage conversion circuit has been proposed, enabling low power biosensor arrays.

Design of Fully Integrated Impedimetric CMOS Biosensor for DNA Detection

This paper described a label-free and fully integrated impedimetric biosensor using standard Complementary Metal Oxide Semiconductor (CMOS) technology to measure both capacitance and resistance of the electrode-electrolyte interface. Conventional impedance biosensors usually use bulky and expensive instruments to monitor the impedance change. This paper demonstrates a low power, high gain and low cost impedance readout circuit design for detecting the biomolecular interactions of deoxyribonucleic acid (DNA) strands at the electrode surface. The proposed biosensor circuit is composed of a transimpedance amplifier (TIA) with two quadrature phase mixers and finally integrated with 5μm x 5μm microelectrode based on 0.18μm Silterra CMOS technology process with 1.8V supply. The output value of the readout circuit is used to estimate the amplitude and phase of the measured admittance. The developed TIA can achieve a gain of 88.6dB up to a frequency of 50MHz. It also has very good linearity up to 2.7mA and the overall dynamic range is approximately 90dB.

Monolithic Biosensor for Gene-Based Disease Detection

In this paper, charge-modulated field effect transistor based detection circuit is presented for the purpose of electrical detection of DNA hybridization. The readout circuit consists of a drain follower and a compensated differential amplifier. It is able to achieve a voltage gain of 56.94 dB in the frequency range up to 6.79 kHz using 0.18μm Silterra CMOS process. The compensation technique is used in the detection circuit in order to improve the phase margin to 52.66o. The proposed potentiometric biosensor eliminates the need for a reference electrode which can offer great potential for miniaturized sensor array that would enable a massive parallel detection of DNA assay.