Wireless sensor application wide ultra low-power RF technology exposition (1)

Wireless medical devices to improve patient comfort and has not previously been the no way to monitor patients.

But first of all, the power consumption is especially important to be optimized.

Wireless sensor nodes

Wireless devices has changed the way we work and leisure environments — they may also be similarly changed our medical facilities.

Wireless device is an interesting application is a wireless sensor nodes, which can be used to monitor heart rate, EEG, temperature, blood pressure and other vital signs.

At present, has been using intensive care unit to monitor the patient body sensor and in the patient's condition changes remind doctors.

Sensor connected to the computer through a cable. Although in this case this is not a fundamental problem, but the wireless sensor nodes can let other parts of the hospital and outpatient benefits are obvious.

Figure 1: a sleep monitoring system consists of a strip with three sensor node of the scarf.

These three sensor node on two road EGG channel (EEG), two eye-electro, 1 channel actin measured electrical diagrams, monitoring the activities of the brain, eye and jaw muscles of activities.

At present, to sleep monitoring test patients must put on by a bunch of wires connected to the computer of the sensor, which will make patients feel uncomfortable.

Research institutions IMEC and Holst Centre developed a scarf-wireless monitoring system, the system has five integrated sensors, able to do effective collection and transfer the required sleep test all data (Figure 1).

This device can improve the patient in the hospital for sleep comfort in the testing process, and eliminates the cable.

Netherlands sleep disorders Center Kempenhaeghe completed testing indicates that the wireless monitoring system like Wired systems running efficiently. You can imagine: in the not too distant future, the patients go to the doctor to a sleep test CAP, and then at home to complete the test. By sleep disorders specialty physicians remote analysis results.

Figure 2: integrated in the cap on the EEG sensor for monitoring patients with epilepsy

Once the wireless sensor nodes become mainstream, there will be a large number of new applications emerging.

Sensor nodes can be integrated into many products, including blankets, car seats and clothes, etc. For example, integration with EEG sensor baseball cap can continuously measuring the brain activity in patients with epilepsy (Figure 2). Shirts can also double as ECG monitor. Wireless sensor nodes has unlimited uses.

To achieve our vision of wireless sensor nodes, still require significant research and development.

One of the challenges associated with power consumption. Because the node is not a wired connection to the grid, you must use the battery. While the battery size should be as small as possible to match the integrated into clothes in the micro system. If small is not the first consideration, then the lower power consumption means that the device can support longer autonomy or support other more features, but on implantable sensor nodes, the battery can long period is required.

Figure 3: sensor node's basic components.

IMEC and Holst Centre is developing an electrocardiogram strap, the product like an athlete takes the traditional heart monitor strips.

This tape is not only able to monitor the heartbeat, you can record and transmit the complete ECG. The device is available with heart of outdoor activity enthusiasts very easy to use, or in competitive activities (the scallops in the Brussels Marathon already tested). Purpose of the challenge is to bring the system miniaturization and achieve a sufficient level of independence. According to the application, you may want to use for a few days or permanent use. The ultimate goal is to apply this paragraph e heart experts integrated into a small box, but this small box you want to be attached to a belt (Figure 4), or can be embedded into a shirt, the better.

Figure 4: an IMEC and Holst Centre has developed an ECG.

Researchers are currently attempting to reduce its size while improving their autonomy.

Power to inspect the sensor to a separate standard widget budget ECG sensor node power: sensing and reading unit, wireless communications, digital signal processor (DSP) and power supply unit.

Obviously, the node is the most power radio chip, RF chips for wireless transmission of sensor data (Figure 5). Normally, wireless communication features of the power consumed by the total power budget of 50 per cent to 85 per cent.

Figure 5: sensing

For nodes that constitute part do power analysis results showed that sensor node in most energy is wireless components.

Figure 6: another reduction sensor node-power approach is to use a dedicated low-power RF components instead of the non-specialized design for low power RF components.

If the IMEC's BAN RF components instead of off-the-shelf Zigbee such RF components to transfer the untreated electrocardiogram, can reduce overall system power 10 times.