Fatimah Ibrahim | University of Malaya, Malaysia (original) (raw)

Uploads

Papers by Fatimah Ibrahim

This paper presents the fabrication of low-resistance carbon MEMS/NEMS as material for biosensing... more This paper presents the fabrication of low-resistance carbon MEMS/NEMS as material for biosensing. The carbon source is the negative photoresist SU8 epoxy. At room temperature the SU8 is in liquid form, making it easier to mix with nanoparticles. The SU8 epoxy is mixed with single-walled-Carbon-Nanotubes (swCNTs) and stirred for 48 h. The experimental variable was the weight percentage (wt%) of swCNTs in the SU8 epoxy. The controlled variables were the layer thickness and experimental environment such as the room’s humidity and furnace model. The silicon wafer was used as substrate because it can withstand high temperatures during the pyrolysis step. The spin coater was used for coating the mixture onto the substrates uniformly. The spinning process was repeated for sample design 2 and 3 to obtain the double layer characteristic. Samples were exposed to ultra-violet (UV) radiation for 40 s. This process is called photolithography. The samples were heated on the hotplate before (pre-...

IFMBE Proceedings

The purpose of this study was to assess the effect of light-tip distance on the shear bond streng... more The purpose of this study was to assess the effect of light-tip distance on the shear bond strength and failure site of brackets cured with three different light curing units: a high-intensity halogen (Astralis 10, 10-second curing), a light-emitting diode (LED, e-Light, six-second curing), and a plasma arc (PAC System, four-second curing). One hundred and thirty-five bovine permanent mandibular incisors were randomly allocated to nine groups of 15 specimens each. Stainless steel brackets were bonded with a composite resin to the teeth, and each curing light was tested at zero, three, and six mm from the bracket. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. When the three light curing units were compared at a light-tip distance of zero mm, the three lights showed no significantly different shear bond strengths. At light-tip distances of three and six mm, no significant differences were found between the halogen and plasma arc lights, but both lights showed significantly higher shear bond strengths than the LED light. When evaluating the effect of the light-tip distance on each light curing unit, the halogen light showed no significant differences between the three distances. However, the LED light produced significantly lower shear bond strengths at a greater light-tip distance, and the plasma arc lamp showed significantly higher shear bond strengths at a greater light-tip distance. In hard-to-reach areas, the use of PAC system is suggested, whereas the LED evaluated in this study is not recommended.

International Journal of Applied Physics and Mathematics, 2013

This study investigated the muscle activity of the neck extensors (NE), sternocleidomastoideus (S... more This study investigated the muscle activity of the neck extensors (NE), sternocleidomastoideus (SCM) and biceps brachii (BB) muscles in healthy subjects during salat and specified exercises using surface electromyography (EMG). A group of undergraduates aged between 19 to 25 years voluntarily participated in this study. For the assessment of the NE and SCM, the subjects were asked to perform salat (salam's position) and exercise [neck rotation exercise (NRE)]. Subjects were asked to perform takbir's position and biceps dumbbell curl (BDC) to access BB. The EMG and the motion signals of the muscles were recorded. The findings indicate that there were contractions of the muscles during the salat and exercise with difference EMG level. For NE and SCM, Wilcoxon's Rank Sum Test showed a statistically no significant difference between salat and exercise for NE (p = 0.482) and SCM (p=0.161). For the BB, Wilcoxon's Rank Sum Test showed a statistically significant difference between salat and exercise (p<0.05) with differences 18.48% MVC. However, BB showed the EMG level with mild contraction. Therefore, salat may be useful in warm up exercise or in rehabilitation programs. This pilot study can be as initial research about other biomechanical response of human muscle with other position in salat.

Journal of Physical Therapy Science, 2012

This study investigated the activity of the rectus femoris (RF), biceps femoris (BF), tibialis an... more This study investigated the activity of the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius (Gas) muscles of healthy subjects during salat and specific exercises using surface electromyography (EMG). [Methods] A group of undergraduates aged between 19 to 25 years voluntarily participated in this study. For the assessment of the RF muscle, the subjects were asked to perform salat movement [standing to prostration (STP)] and squat exercise (SE) and for the BF, TA and Gas muscles, subjects were asked to perform salat (bowing) and the toe touching exercise (TTE). The electromyograms of the muscles were recorded and analyzed. [Result] The findings indicate that there were contractions of the muscles during the salat and exercises with difference EMG levels. Wilcoxon's Rank Sum Test found a statistically no significant differences between salat and the specific exercises for RF, BF and Gas. For TA, the test revealed a statistically significant difference between salat and the specific exercise with a difference of 5.67%MVC. [Conclusion] Salat may be useful in warm up or in rehabilitation programs. This pilot study conducted initial research into the biomechanical responses of human muscles in various positions of salat.

Biosensors & bioelectronics, Jan 9, 2018

Nanowire sensors offer great potential as highly sensitive electrochemical and electronic biosens... more Nanowire sensors offer great potential as highly sensitive electrochemical and electronic biosensors because of their small size, high aspect ratios, and electronic properties. Nevertheless, the available methods to fabricate carbon nanowires in a controlled manner remain limited to expensive techniques. This paper presents a simple fabrication technique for sub-100 nm suspended carbon nanowire sensors by integrating electrospinning and photolithography techniques. Carbon Microelectromechanical Systems (C-MEMS) fabrication techniques allow fabrication of high aspect ratio carbon structures by patterning photoresist polymers into desired shapes and subsequent carbonization of resultant structures by pyrolysis. In our sensor platform, suspended nanowires were deposited by electrospinning while photolithography was used to fabricate support structures. We have achieved suspended carbon nanowires with sub-100 nm diameters in this study. The sensor platform was then integrated with a mic...

PLOS ONE, 2015

The development of micro-power generators for centrifugal microfluidic discs enhances the platfor... more The development of micro-power generators for centrifugal microfluidic discs enhances the platform as a green point-of-care diagnostic system and eliminates the need for attaching external peripherals to the disc. In this work, we present micro-power generators that harvest energy from the disc's rotational movement to power biomedical applications on the disc. To implement these ideas, we developed two types of micro-power generators using piezoelectric films and an electromagnetic induction system. The piezoelectric-based generator takes advantage of the film's vibration during the disc's rotational motion, whereas the electromagnetic induction-based generator operates on the principle of current generation in stacks of coil exposed to varying magnetic flux. We have successfully demonstrated that at the spinning speed of 800 revolutions per minute (RPM) the piezoelectric film-based generator is able to produce up to 24 microwatts using 6 sets of films and the magnetic induction-based generator is capable of producing up to 125 milliwatts using 6 stacks of coil. As a proof of concept, a custom made localized heating system was constructed to test the capability of the magnetic induction-based generator. The heating system was able to achieve a temperature of 58.62°C at 2200 RPM. This development of lab-on-a-disc micro power generators preserves the portability standards and enhances the future biomedical applications of centrifugal microfluidic platforms.

Lab on a Chip, 2015

Reversible thermo-pneumatic valves (RTPVs) manipulate thermal energy to reversibly block or open ... more Reversible thermo-pneumatic valves (RTPVs) manipulate thermal energy to reversibly block or open microchannels. The valves prevent the evaporation of reagents during thermocycling periods. The cartridge is used for sequential aliquoting to prepare multiple PCR reaction mixtures for the detection of the Dengue virus.

PloS one, 2015

A centrifugal compact disc (CD) microfluidic platform with reservoirs, micro-channels, and valves... more A centrifugal compact disc (CD) microfluidic platform with reservoirs, micro-channels, and valves can be employed for implementing a complete immunoassay. Detection or biosensor chambers are either coated for immuno-interaction or a biosensor chip is inserted in them. On microfluidic CDs featuring such multi-step chemical/biological processes, the biosensor chamber must be repeatedly filled with fluids such as enzymes solutions, buffers, and washing solutions. After each filling step, the biosensor chamber needs to be evacuated by a passive siphoning process to prepare it for the next step in the assay. However, rotational speed dependency and limited space on a CD are two big obstacles to performing such repetitive filling and siphoning steps. In this work, a unique thermo-pneumatic (TP) Push-Pull pumping method is employed to provide a superior alternative biosensor chamber filling and evacuation technique. The proposed technique is demonstrated on two CD designs. The first design...