Week 1: Introduction & Literature Review

Welcome to my blog! 

Dehydration is a common but is an often overlooked health issue that can result in fatigue, headaches, and more serious complications if not addressed. My project will focus on developing a low-cost and wearable hydration monitoring patch to detect early signs of dehydration using simple physiological signals like skin temperature and humidity. This device will be meant for everyday users, specifically older populations who might not recognize dehydration symptoms. By combining accessible sensors with a compact, user-friendly design, I aim to create a prototype of an affordable tool that can make hydration tracking more practical.

This week, I started off with my literature review, focusing on existing research and hydration-monitoring technologies, which will help me refine my prototype to ensure that it can address a gap in both research and the current market.

Over the past five years, wearable, patch-like hydration monitoring technologies have become more common and more advanced. Many research studies that I have read describe flexible smart patches that are made using printed electronics, microfluidic channels, and electrochemical sensors to measure various dehydration indicators like sodium, lactate, glucose, and pH in sweat. For example, one study created a fully printed patch to monitor pH and hydration levels in wounds to detect possible signs of infection (Iversen et al., 2021). Other researchers developed wearable patches, which were validated through lab calibrations and exercise trials done on humans and compared their results to gold-standard hydration measurements, like weight loss (Zhu et al., 2022). One study even combined a smart mouthguard to measure saliva osmolality with a chest patch that tracks ECG, skin temperature, and movement (Kim et al., 2024). To sum it up, most prior research focuses on high-performance sensing systems tested in controlled athletic environments.

Current products on the market also demonstrate a similar trend. Companies like Nix Biosensors, hDrop, MX3 Diagnostics, and the Gx Sweat Patch are mainly designed for athletes. These devices all typically measure sodium concentration in sweat and the rate at which athletes are sweating to help athletes optimize their performance. However, many of them are costly (over $100) and are either single-use patches or require disposable cartridges. The current ones on the market are functional and impressive, but they are built for high-performance athletes rather than the average person. 

My project will take a different approach: instead of focusing on elite athletes or utilizing expensive electrochemical sensing systems, I will be designing a low-cost wearable patch for early dehydration detection in older adults. Rather than using sodium levels in sweat as an indication of dehydration, my device will combine multiple physiological signals to identify potential dehydration levels. 

The materials that I plan to use are a DS18B20 temperature sensor, a DHT22 humidity sensor, and an Arduino Uno, to start off. The DS18B20 will measure skin temperature, as skin temperature will increase when losing fluids. The DHT22 will measure the microclimate humidity near the skin, as increased humidity near the skin’s surface would be an indication of fluid loss. So, instead of looking at just one metric, I will combine these two different signals to detect patterns that will indicate dehydration before severe symptoms occur. 

Works Cited:

1. Iversen, M., Monisha, M., & Agarwala, S. (2021). Flexible, wearable and fully-printed smart patch for pH and hydration sensing in wounds. International Journal of Bioprinting, 8(1), 447. https://doi.org/10.18063/ijb.v8i1.447
2. Kim, K. R., Kang, T. W., Kim, H., Lee, Y. J., Lee, S. H., Yi, H., Kim, H. S., Kim, H., Min, J., Ready, J., Millard‐Stafford, M., & Yeo, W. (2024). All‐in‐One, wireless, Multi‐Sensor integrated Athlete Health Monitor for Real‐Time continuous detection of dehydration and physiological stress. Advanced Science, 11(33), e2403238. https://doi.org/10.1002/advs.202403238
3. Zhu, Y., Haghniaz, R., Hartel, M. C., Guan, S., Bahari, J., Li, Z., Baidya, A., Cao, K., Gao, X., Li, J., Wu, Z., Cheng, X., Li, B., Emaminejad, S., Weiss, P. S., & Khademhosseini, A. (2022). A breathable, Passive‐Cooling, Non‐Inflammatory, and biodegradable Aerogel electronic skin for wearable Physical‐Electrophysiological‐Chemical analysis. Advanced Materials, 35(10), e2209300. https://doi.org/10.1002/adma.202209300