Nanogenerators For Implantable Biomedical Devices

ABSTRACT:

Materials Science research is now entered a new phase where the structure and properties of materials are investigated, characterized and controlled at the nanoscale. Though as sophisticated as their larger counterparts, these devices are still burdened because they rely on an outside power. The size of the entire device is determined by the size of the power source. Batteries and other traditional sources are too large, and tend to negate the size advantages of nano devices. Also, batteries being used at present require toxic chemicals and have to be replaced periodically. To overcome these challenges; researchers are finding alternative ways to power nano devices. One promising development is the nano generator. In this talk, we specially emphasized application of nano generators, importance of nanowires in building a nano generator. Nanogenerator allows us to harvest or recycle energy from many sources to power these devices. The nanogenerators take advantage of the unique coupled piezoelectric and semiconducting properties of zinc oxide nanostructures, which produce small electrical charges when they are flexed.

KEYWORDS:

Nano wire, Low power miniature sensors, Piezoelectric effect, Electric power, VIBES (Vibration Energy Scavenging)

INTRODUCTION:

An array of zinc-oxide nanowires that generates current when vibrated with ultrasonic waves could provide a new way to power biological sensors and nano devices. Using ultrasonic waves to vibrate an array of zinc-oxide nanowires, researchers at Georgia Tech have made a tiny generator that can produce direct current. By taking advantage of the fact that zinc-oxide nanowires are piezoelectric, they converted mechanical energy into electricity and by finding a way to collect electricity from multiple nano wires, the researchers took a big step toward a practical nano-scale power generator.

NANOWIRE:

Nanowires and other nano materials have shown great promise in creating future generations of electronic devices. New work from researchers at NIST, George Mason University, and Kwangwoon University in Seoul has generated a hybrid memory device that uses both conventional techniques and exploits the properties of silicon nanowires.

Electron micrograph shows the gallium nitride wires growing on a silicon substrate (colour added for contrast) The hybrid structure exhibited by these devices means that they are more reliable than other nanowire approaches, and they should be easier to integrate into modern components. The hybrid device that the team built is a non-volatile memory device similar to a flash device, which retains its memory even when power is turned off.The wires are generally between 30 and 500 nanometers (nm) in diameter and up to 12 micrometers long. When excited with a laser or electric current, the wires emit an intense glow in the ultraviolet or visible parts of the spectrum, depending on the alloy composition. The nanowires are grown onto an oxide nitride- oxide zinc substrate. When positive voltage is applied, electrons tunnel down into the substrate; when negative voltage is applied, the electrons tunnel back into the wires. When no voltage is present, the device can be read, and the position of the electrons will represent a “1″ or a”0″.

WHAT IS A NANO GENERATOR?

Generation of electricity is necessary for some extremely small devices (nano devices) like medical devices, sensors and portable electronics without the need for bulky batteries or other energy sources. Instead of batteries, electricity for such devices would come, for instance, from muscle contraction or other body movements. Nano generator is one such device. Zinc oxide nanowires in nano generator produce electricity via a long-known phenomenon termed the piezoelectric effect. It occurs in certain materials, which change mechanical energy — from flexing or twisting, for instance — into electricit

To know more about the nanogenerator, how it works, future scope, mail me at muthuvignesh88@gmail.com

My Implant Training In Global Hospital

Introduction:               

1. Biomedical instrumentation is the instruments we use in biomedical engineering, and biomedical engineering is the application of engineering field in the medical field.
2. Diagnosis is the process of finding out the disease. Eg. Pulse rate is used in the determination of brachy  (pulse rate more than 72) and trachy (pulse rate less than 72)
3. ECG works based on impedance between two points in our body. After amplification the output of the ECG is of the order of micro volts.
4. The vital parameters of the monitors are;

• ECG
• sPO2
• Heart rate
• Temperature
• Non invasive blood pressure monitor

        5.    Non invasive blood pressure monitor the diagnosis involves the monitor of all the above  parameters

6.    In addition to the above there are also additional parameters such as IBP( Invasive blood pressure measurement ) and ET2CO2(Exhalation CO2 measurement)

7.    In spo2 measurement it consists of detector and diode. The light illumination is measured in terms of LUX.

8.    There are 4 types of ventilators:

• Synchronized Intermediary Mandatory Ventilator  = 50% patient
• 50% ventilatorContinuous mandatory ventilator  = 100% ventilation
• Spontaneous mandatory ventilator = 100% patient 
• Advanced support ventilator  = all above

Equipments types:

·      Diagnostic

·      Therapeutic

·      Combined



CARDIOLOGY

1. Treadmill T2100 = used to find the physical response of the heart. The patient is allowed to walk in this threadmill and the heart activity is noted down.

FIBRILLATOR AND DEFIBRILLATOR: 

1. Fibrillator is used in stopping the ventricular fibrillation in cases of heart transplant surgery to stop the blood supply.

2. High frequency is used in fibrillator. In case of initiating the heart beat defibrillator is used.it consists of two paddles. Right is one  for charging. Left is for receiving. Right is placed at the apex and the left is placed at the sternum.

3. Lowest energy is about 2 joules and highest energy is about 200 joules.

1.CV 7O is used in ECHO Cardiography. It’s a DOPPLER Ultra Sound machine. It can be used to monitor the functioning of heart.
2. It’s a Doppler Ultra Sound machine. It can be used to monitor the functioning of heart. Here Ultrasound radiations are passed through the internal organs to diagnosis the functioning of the internal organs.

 

MOBILE MONITORING WITH WEARABLE PHOTOPLETHYSMOGRAPHIC BIOSENSENSORS

     

          Wearable biosensors (WBS) will permit continuous cardiovascular (CV) monitoring in a number of novel settings. Benefits may be realized in the diagnosis and treatment of a number of major diseases. WBS, in conjunction with appropriate alarm algorithms, can increase surveillance capabilities for CV catastrophe for high-risk subjects. WBS could also play a role in the treatment of chronic diseases, by providing information that enables precise titration of therapy or detecting lapses in patient compliance.

Wearable Bio-sensors (WBS)

          WBS could play an important role in the wireless surveillance of people during hazardous operations (military,fire-fighting, etc.), or such sensors could be dispensed during a mass civilian casualty occurrence. Given that CV physiologic parameters make up the “vital signs” that are the most important information in emergency medical situations, WBS might enable a wireless monitoring system for large numbers of at-risk subjects. This same approach may also have utility in monitoring the waiting room of today’s overcrowded emergency departments. For hospital inpatients who require CV monitoring, current biosensor technology typically tethers patients in a tangle of cables, whereas wearable CV sensors could increase inpatient comfort and may even reduce the risk of tripping and falling, a perennial problem for hospital patients who are ill, medicated, and in an unfamiliar setting.


INTRODUCTION:

           
          The ring sensor is an ambulatory, telemetric, continuous health-monitoring device. This WBS combines miniaturized data acquisition features with advanced photoplethysmographic (PPG) techniques to acquire data related to the patient’s cardiovascular state using a method that is far superior to existing fingertip PPG sensors. In particular, the ring sensor is capable of reliably monitoring a patient’s heart rate, oxygen saturation, and heart rate variability. Technical issues, including motion artifact, interference with blood circulation, and battery power issues, will be addressed, and effective engineering solutions to alleviate these problems will be presented. Second, based on the ring sensor technology the clinical potentials of WBS monitoring will be addressed.



 PRINCIPLE:

           This wearable bio-sensor works on the basis of photo-plethysmographic principle. Plethysmographic determination in which the intensity of light reflected from the skin surface and the red cells below is measured to determine the blood volume of respective area.There are two types, transmission and reflectance.



COMPONENTS:

The Wearable Biosensor mainly composed of the following components:

1. Optical Sensor Unit
2. Analog and digital processing unit
3.  RF transmitter, all of which are encapsulated in a compact body
4. Powered by a tiny cell battery used for wristwatches.

Overcoming artifact due to external force by placing the LED & PD more interior within the frame. 

           The above figure shows the first ring sensor prototype that contains an optical sensor unit, analog and digital processing units, and an RF transmitter, all of which are encapsulated in a compact body and powered by a tiny cell battery used for wristwatches. The ring has a PIC microcomputer performing all the device controls and low-level signal processing, including LED modulation, data acquisition, filtering, and bi-directional RF communication. The acquiredwaveforms, sampled at 100 Hz, are transmitted to a PDA or a cellular phone carried by the patient through an RF link of 105 kbps at a carrier frequency of  15 MHz. The cellular phone then accesses aWeb site for data storage and clinical diagnosis.

           An obvious source of signal corruption results from the direct interaction of the sensor unit with the wearer’s surrounding environment; e.g., holding objects, touching surfaces, etc. Thus, the body of the ring must separate the sensor unit in order to decouple the sensor unit from these interactions. To this end, a double ring configuration was designed and implemented, as shown in following. The disturbance force is born by the outer ring and is not transmitted to the inner ring holding the sensor unit. Moreover the outer ring serves as an optical shield for protecting the sensor unit from the ambient light. In this early development, the power consumption of the LEDs and the embedded CPU clock were a major bottleneck limiting the design. The distance between the LEDs and PDs had to be shortened for power saving considerations, and the CPU clock was minimized in order to extend the battery life to a few weeks. To evaluate the overall performance of motion artifact resistance, data were continually taken from a wearer performing daily office work (e.g., typing and writing) and the acquired data were examined to see how often the waveforms were corrupted and how many of them were usable. The result was that 35% of the data in a two-hour session was not corrupted and usable.

             In order to know more about results obtained(output of WBS), various artifacts produced in WBS which prevents precise output (such as motion artifact) and how it can be eliminated through adopting methodologies like sensor arrangement, transmural pressure, using adaptive filter which involves LMS algorithm,  noise rejection method please mail me( muthuvignesh88@gmail.com ). In addition to that, scattering of light is a typical problem in this WBS which must be considered as a severe problem.