Spatiotemporal Measurement of Arterial Pulse Waves Enabled by Wearable Active-Matrix Pressure Sensor Arrays

Abstract

Wearable pressure sensors have demonstrated great potential in detecting pulse pressure waves on the skin for the noninvasive and continuous diagnosis of cardiac conditions. However, difficulties lie in positioning conventional single-point sensors on an invisible arterial line, thereby preventing the detection of adequate signal amplitude for accurate pulse wave analysis. Herein, we introduce the spatiotemporal measurements of arterial pulse waves using wearable active-matrix pressure sensors to obtain optimal pulse waveforms. We fabricate thin-film transistor (TFT) arrays with high yield and uniformity using inkjet printing where array sizes can be customizable and integrate them with highly sensitive piezoresistive sheets. We maximize the pressure sensitivity (16.8 kPa −1 ) and achieve low power consumption (10 1 nW) simultaneously by strategically modulating the TFT operation voltage. The sensor array creates a spatiotemporal pulse wave map on the wrist. The map presents the positional dependence of pulse amplitudes, which allows the positioning of the arterial line to accurately extract the augmentation index, a parameter for assessing arterial stiffness. The device overcomes the positional inaccuracy of conventional single-point sensors, and therefore, it can be used for medical applications such as arterial catheter injection or the diagnosis of cardiovascular disease in daily life.

Printable inks and deformable electronic array devices

“…It enables low-cost and large-area additive manufacturing using digital layouts under ambient conditions. 62–65 The features are determined by the diameter of the nozzle, and the speeds of the motion stage and the printer head. The inkjet printing system consists of a motion stage, a machine vision system, and a control system with printer heads (Fig.…”

Mechanical Sensors for Cardiovascular Monitoring: From Battery-Powered to Self-Powered

“…This spatially insensitive, low-power (≈35 nW) LCPS can be easily installed by the user while ensuring the sensing ability of the sensor’s high-fidelity epidermal pulse signal. In addition, using the wearable pressure sensor array to measure the temporal and spatial pulse waves to obtain the best pulse waveform can also be regarded as a solution [ 18 , 39 ]. Baek et al used inkjet printing technology to fabricate thin-film transistor (TFT) arrays integrated with thin sheets of highly sensitive piezoresistive sensors ( Figure 3 B) [ 39 ].…”

“…In addition, using the wearable pressure sensor array to measure the temporal and spatial pulse waves to obtain the best pulse waveform can also be regarded as a solution [ 18 , 39 ]. Baek et al used inkjet printing technology to fabricate thin-film transistor (TFT) arrays integrated with thin sheets of highly sensitive piezoresistive sensors ( Figure 3 B) [ 39 ]. The operating voltage of TFT was strategically modulated to maximize pressure sensitivity (16.8 kPa −1 ) with low power consumption (101 nW).…”

“…Reprinted/adapted with permission from Ref. [ 39 ]. ( C ) Ultrathin flexible PZT pressure sensor and the piezoelectric potential distribution, the inset indicates a cross-sectional SEM image (scale bar, 5 µm).…”

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