A photoacoustic patch for three-dimensional imaging of hemoglobin and core temperature

Abstract

Electronic patches, based on various mechanisms, allow continuous and noninvasive monitoring of biomolecules on the skin surface. However, to date, such devices are unable to sense biomolecules in deep tissues, which have a stronger and faster correlation with the human physiological status than those on the skin surface. Here, we demonstrate a photoacoustic patch for three-dimensional (3D) mapping of hemoglobin in deep tissues. This photoacoustic patch integrates an array of ultrasonic transducers and vertical-cavity surface-emitting laser (VCSEL) diodes on a common soft substrate. The high-power VCSEL diodes can generate laser pulses that penetrate >2 cm into biological tissues and activate hemoglobin molecules to generate acoustic waves, which can be collected by the transducers for 3D imaging of the hemoglobin with a high spatial resolution. Additionally, the photoacoustic signal amplitude and temperature have a linear relationship, which allows 3D mapping of core temperatures with high accuracy and fast response. With access to biomolecules in deep tissues, this technology adds unprecedented capabilities to wearable electronics and thus holds significant implications for various applications in both basic research and clinical practice.

Current Trends in Nanotheranostics: A Concise Review on Bioimaging and Smart Wearable Technology

“…The hemoglobin in the blood expands due to the localized heating under incident laser thus causing an acoustic wave which is detected by the piezoelectric transducer. Such an epidermal patch can generate high spatial resolution image of single molecules (Figure 3 B) 60 .…”

“…The hemoglobin in the blood expands due to the localized heating under incident laser thus causing an acoustic wave which is detected by the piezoelectric transducer. Such an epidermal patch can generate high spatial resolution image of single molecules (Figure 3B) [60]. The hemoglobin molecules in red blood cells go through a thermoelastic expansion after absorbing optical energy, which then transmits acoustic waves into the surrounding media.…”

“…(B) Schematics of soft-photoacoustic patch for detection of hemoglobin and measuring temperature.The hemoglobin molecules in red blood cells go through a thermoelastic expansion after absorbing optical energy, which then transmits acoustic waves into the surrounding media. The transducer array will gather the photoacoustic waves and then transmit them to a backend system for data processing[60]. Copyright 2022, Nature.…”

An Emerging Era: Conformable Ultrasound Electronics

“…Improvement of ultrasonic performance, such as signal strength and signal‐to‐noise ratio, of the flexible sensor is a future research subject for more reliable and reproducible measurements. After that, Sheng's group reported several work on the Type III of the cUSE for long‐term cardiac and haemodynamic monitoring, [ 33,254 ] and finally innovated a wearable ultrasonic device for continuous, real‐time and direct cardiac function assessment (Figure 12h–i). [ 45 ] This technology enables dynamic, accurate, wearable monitoring of cardiac performance in a variety of environments.…”

Mn(iii), Fe(iii) and Zn(ii)-serum albumin as innovative multicolour contrast agents for photoacoustic imaging

“…[10][11][12] In the last two decades, several endogenous and exogenous molecules have been described as suitable PAI CAs. [6][7][8]13 For instance, haemoglobin [14][15][16] and melanin [16][17][18] have been widely exploited as natural PAI CAs to gather physiological information in healthy and pathological tissues. These molecules allow the assessment of vascular volume, oxygen content, perfusion, and other relevant parameters.…”