The Doppler shift technique is proven to be an effective method f

The Doppler shift technique is proven to be an effective method for measuring the systolic BP of infants [9].Measuring the BP through pulse wave transit time (PTT) is another selleck chem Ponatinib cuff-less technique and a candidate method for continuous monitoring of BP [10]. Inhibitors,Modulators,Libraries When measuring the PTT, the heart activity is usually monitored with an ECG sensor and a photoplethysmogram (PPG) sensor is placed on a finger, wrist or earlobe to track the pulse travelling from the heart to the peripheral point. Simply, if the arterial pressure is higher, the pulse travels faster. Recently, a wrist module was developed to measure BP by integrating a PPG sensor and ECG sensor into a watch-type monitoring device [11,12]. However, the reliability of measurements and calibration of the device are still issues under investigation.

More recently, another cuff-less design was developed by using combined PTT and oscillometric methods [13�C15]. The system estimates the BP by placing two sensors along the artery; typically, these are at the wrist Inhibitors,Modulators,Libraries and index finger, as shown in Figure 1. However, measuring the blood pressure in this fashion is challenging, due to instabilities in hydrostatic pressure caused by the change of hand position with respect to the heart. Conventional ambulatory BP meters require patients to sit and raise their hand to the heart level. In order to overcome this challenge, a MEMS accelerometer is used to adjust the height of the hand with respect to the heart, to set the hydrostatic pressure offset for the Inhibitors,Modulators,Libraries PTT sensor.

This approach allows the patients move their hands freely by calibrating the PTT sensor response according to the change in hydrostatic pressure. Inhibitors,Modulators,Libraries One benefit is that the local pressure applied to the tissue is trivial compared to the traditional oscillometric devices and does not interrupt the blood flow. Thus, this design is a promising approach to achieve continuous, non-invasive and unobtrusive monitoring of blood pressure and is one of the cutting-edge technologies under investigation at this time.Figure 1.Blood pressure sensor by MIT [15].2.2. Monitoring the Blood Glucose LevelsMost commercial blood glucose (BG) monitoring devices employ invasive techniques; usually, a blood sample must be obtained by pricking the finger with a lancet. The blood sample obtained is then exposed to a strip and the BGL calculated by inserting the strip into a digital monitor.

Diabetic patients should perform the task at least 5�C6 times a day for tight metabolic control. However, the finger pricking task is reported to be a painful procedure, leading some to take Cilengitide fewer samples, hence risking problems induced by poor BGL management.Some commercial U0126 side effects systems (e.g., Medtronic��s MiniMed and Guardian products [16]) are termed ��minimally-invasive�� continuous monitoring systems. Typically, a (disposable) bio-sensor needle is inserted under the skin on the abdomen and the BGL is derived from the glucose level in the interstitial tissue fluid.

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