Biomedical Engineering News

Researchers at Universidad Rovira i Virgili have created a biosensor, an electrical and biological device, which is able to selectively detect the Candida albicans yeast in very small quantities.

Candida albicans is a diploid fungus (a form of yeast), which is capable of sexual reproduction but not of meiosis, and a causal agent of opportunistic oral and genital infections in humans.

“The technique uses field-effect transistors (electronic devices that contain an electrode source and a draining electrode connected to a transducer) based on carbon nanotubes and with Candida albicans-specific antibodies”, Raquel A. Villamizar, lead author of the study says.

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Researchers at Duke University biomedical engineering department have developed a laboratory robot that can locate the earliest traces of a mass in simulated breast tissue and reach that mass with a biopsy needle.

The robot can move in three axis right now. Their next goal is developing a robot that can move in 6 axis.

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Breast biopsy is a surgical procedure which all or part of lump is removed and tested for maligancy.

U.S News publishes rankings for universities and their different programs. Following are the top 10 ranked biomedical engineering schools:

1. Johns Hopkins
2. Georgia Tech
3. University of California – San Diego
4. Duke University
5. MIT
6. University of Washington
7. Rice University
8. University of Pennsylvania
9. Boston University
10. Stanford University

You can read more about the rankings here.

Currently surgeons have to operate multiple times for removing breast cancer tumors about 40% of the time. Researchers at Duke University have invented a unique optical imaging technique that enables surgeons to review tumor-margin status during surgery and reduce the current re-surgery rates.

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Researchers at Purdue University have developed a technique using spun-sugar filaments to create a scaffold of tiny synthetic tubes that might serve as conduits to regenerate nerves severed in accidents or blood vessels damaged by disease.

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Biosensor can be defined as a device which is used to detect an analyte. Microfluidic bio sensor comes mainly in two categories. They are Florescent based devices and electrochemistry based devices. This categorisation of the microfluidic biosensor is based on its detection capability. One important characteristic of both these devices is that both of them utilises functional liposomes for target recognition and binding. A number of biorecognition elements are used to functionalise liposomes.

They include receptors, antigens, antibodies and nucleic acid probes. For the purpose of immobilisation another biorecognition element is used. It is used for the immobilisation of target-liposome-magnetic bead complex within the microfluidic device. This type of biorecognition element will be bounded to paramagnetic beads. After the completion of immobilisation signal amplification will be done. This is done with the help of signal generating molecules, which will be in the encapsulated form. It is the lysis of the lipisome which allow the signal amplification. It is applicable to both florescent based devices and electrochemistry based devices.

Inside the microfluidic biosensor device there will be a serpentine channel. This is the channel which is used for the formation of two other channels. The first channel is formed by liposome-target-magnetic bead complex. The second channel delivers the surfactant which is utilised to lyse the liposome. The liposome will be captured at the capture zone. Capture zone is the meeting point of these two channels. It is located at the downstream in the junction of the two channels. The target detection by the microfluid biosensor depends on the type of biorecognition element used.

In order to evaluate the magnetic capture zone the device must be mounted on to a florescence scope. Then only the capture zone can be evaluated. The background signal will be negligible if there is no target present. If any target is present then a group of lipisome target can be seen at the output side. But there won’t be much amplification in the signal received. Further amplification is brought about by the surfactant, which is delivered from the second channel. Then the output will look like a beam of florescent particles.

In the case of a microfluid biosensor which is based on electrochemistry, electroactive compound will be used rather than florescent molecules. Florescent molecules are used by florescent based microfluidic biosensor devices. The electroactive microfluidic biosensor utilise Inter Digitated Ultramicroelectrode Array (IDUA). IDUA contains a number of anode and cathode pads arranged in a systematic manner. They are nanofabricated. The anode pad as well as the cathode pad consists of fingers which are held opposite to each other in an over lapping pattern. Working of the IDUA is based on the Red-ox (Reduction-oxidation) reaction. When any electroactive red-ox couple comes in contact with this IDUA, reduction of the oxidised form takes place on the cathode part.

Also, a small voltage must be given to the IDUA device. Since the anode and cathode pads are held opposite to each other, the reduced form gets converted back to the oxidised form in the anode placed adjacent to the cathode. Again it will be transferred into the cathode and turned into the reduced form. Thus this cyclic process goes on as a result of which an electron flow will be created. This electron flow results in a current which is proportional to the concentrate of analyte given.

The result can be displayed on any devices by properly connecting the output to the display. Thus the concentration of the analyte can be found out using the IUDA. The output current developed can be detected with the help of a potentiostat.