Wireless Transceiver Technology For Medical Devices
Wireless Medical Device
The combination of medical science and electromechanical technology has created unbelievable developments in the field of medicine. The most important invention is the wireless technology used in various health monitoring systems. These monitoring systems ensures faster rate of mobility and data transmission. These are mostly Bluetooth Low Energy wireless devices. They are controlled by the wireless transceiver technology. imec Holst center and Fujitsu Laboratories has brought out a new wireless transceiver for human body use. They are used in (BAN) Body Area Network which is applicable for medical monitoring systems. These systems require around 400 MHz-band which they easily receive from BAN.
History behind formation of the new Wireless Transceiver
All the primitive technologies that were used to collect data from the patient-monitoring machines were mainly wireless network (preferably BAN) of sensors. But the sensor nodes used to set up high rate of battery consumption and low rate of data transfer. This made the patients as well as the medical practitioners a matter to worry about. Hence for convenience, the battery life of the sensors nodes must be increased.
Benefits of the New Wireless Transceiver Technology for Medical devices
The wireless transceiver which was previously used to measure brain signals or other vital signals required more than a dozen milliwatts of electric consumption. But this new wireless transceiver designed by imec Holst centre and Fujitsu Laboratories consumed an electric power of 1.6 milliwatts for data input. Also 1.8 milliwatts for data output. Besides this the new wireless transceiver is highly efficient because it increases the battery life. It increases the battery life of the health monitoring machines to about ten times more than primitive sensor machines. This reduces the inconvenience of frequently changing or charging the battery.The patients can easily carry these wireless sensor devices as they are very light weight. They can also move about keeping the device attached to their body. So one need not sit or lay down in front of the monitor which is connected to the respective sensor device.
Technology behind formation of the New Wireless Transceiver
The sensor nodes which were responsible in collating the data from the monitoring machines were nothing but wireless transceivers which required high amount of power supply in order to function. Now the aim of the scientist of Fujitsu was to create a more compact and efficient wireless transceiver which had less power consumption technique and can easily adopt the variation in rate of data transmission from the monitoring machine without adding any extra circuit. This was why a more efficient wireless transceiver was constructed.
Architecture of the New Wireless Transceiver
The new wireless transceiver was designed keeping in mind that it is compatible at 400MHz bandwidth which was standardized by IEEE 802.15.6 (the international standard for BAN). This technology supported two varied modes viz,
- For transmitting brainwaves, images and other data, a 4.5 Mbps high speed mode is constructed.
- For low speed and low power mode while the sensors are in a standby position, a 11.7 Kbps low speed mode is constructed.
Let us have a look on the simplified version of the two different architectures used in the new wireless transceiver for it to perform efficiently.
4.5 Mbps, three point, high speed mode technology
A transmitter can have high speed mode by simply fixing a transmitting mixer in it. But this transmitting mixer along with its driver circuit increases the rate of power consumption in the technology. Hence for a low power, data variation technology, the following three techniques have been introduced into the system. They support low speed mode, high speed mode and also allow 300 times higher rate of data transmission which result to the power consumption of 1.6 milliwatts while receiving and 1.8 milliwatts while transmitting.
- Instead of using a transmitter, a three point data modulation technology is incorporated into the system. This three point data modulation technology consists of a PLL whose function is to create wireless signal from the respective digital circuit. The PLL receives the high frequency and low frequency signal as input and then transmits the amplified signal as output. This amplified signal acts as an input to the amplifier.
- A dual-varactor circuit is implemented along with the digital three-point modulation for high speed mode. This circuit technology functions in such a way that it elevates the variations in the capacitance of the varactor at the VCO. Then the varactor takes this high frequency signals as input.
- In the above case we came to know about the technology used for high frequency input signals. For low speed or low power input signal, a technology is induced in the system which reduces the VCO modulation baseline current by 90%. In spite of its low power technology, it still allows data modulation.
11.7 Kbps, low speed, digitally controlled receiver technology
For low power demand, the transceiver circuit has been modified into very simple version which resulted at low level energy consumption. It is actually a digital circuit which uses a program that changes it’s characteristic according to demand. It responds to different phase and frequency modulation according to BAN international standard. The modified form of receiver consists of the following components.
The transceiver generally uses the direct-conversion technique which initiates in accepting the baseband signal directly from the incoming digital signal. The 4.5 Mbps mode reduces the frequency of low-pass filter and AD converter via digital circuit. Besides, the 11.7 Kbps low power mode not only reduces the power of low-noise amplifier and mixer but also increases the rate of data transmission.
The new wireless transceiver technology has not only improvised the technique used for human monitoring machines but also brought revolutionary techniques in other field of healthcare industries. Fujitsu has decided not to keep this technology restricted for medical development, but use it in other sectors like, social infrastructure monitoring and improvise network front-end interface technology.