Yindar Chuo

Mechanically Flexible Wireless Multisensor Platform for Human Physical Activity and Vitals Monitoring

Practical usability of the majority of current wearable body sensor systems for multiple parameter physiological signal acquisition is limited by the multiple physical connections between sensors and the data-acquisition modules. In order to improve the user comfort and enable the use of these types of systems on active mobile subjects, we propose a wireless body sensor system that incorporates multiple sensors on a single node. This multisensor node includes signal acquisition, processing, and wireless data transmission fitted on multiple layers of a thin flexible substrate with a very small footprint. Considerations for design include size, form factor, reliable body attachment, good signal coupling, low power consumption, and user convenience. The prototype device measures 55 15 mm and is 3 mm thick. The unit is attached to the patients chest, and is capable of performing simultaneous measurements of parameters, such as body motion, activity intensity, tilt, respiration, cardiac vibration, cardiac potential (ECG), heart rate, and body surface temperature. In this paper, we discuss the architecture of this system, including the multisensor hardware, the firmware, a mobile-phone receiver unit, and assembly of the first proof-of-concept prototype. Preliminary performance results on key elements of the system, such as power consumption, wireless range, algorithm efficiency, ECG signal quality for heart-rate calculations, as well as synchronous ECG and body activity signals are also presented.

Development of a novel contactless mechanocardiograph device

A novel method of detecting mechanical movement of the heart, Mechanocardiography (MCG), with no connection to the subjects body is presented. This measurement is based on radar technology and it has been proven through this research work that the acquired signal is highly correlated to the phonocardiograph signal and acceleration-based ballistocardiograph signal (BCG) recorded directly from the sternum. The heart rate and respiration rate have been extracted from the acquired signal as two possible physiological monitoring applications of the radar-based MCG device.

Sensor Layer of a Multiparameter Single-Point Integrated System

Microfabrication and circuit integration provide sensors with reduced size, improved performance, increased reliability, and lower cost. These microsensors can measure a variety of properties and behaviors, and are typically constructed on a range of substrate materials in combination with signal conditioning, information processing, and data-communication electronics. The challenge remains to integrate multiple sensors, each measuring different parameters with separate supporting electronics, into a single. high-density microsystem. We describe a multiple parameter medical sensor that is suitable for mounting on an active moving patient where mechanical flexibility, tight adhesion, lightweight, small size, and biocompatibility of an easily applied flat stick-on assembly at a single skin site are important considerations. Traditional microintegration technologies, such as system-in-package and system-on-chip, typically create lumped aggregations of components. In this paper, the flat architectural platform of a multiparameter sensor system is presented with microcircuitry distributed across multiple stacked layers that can be easily bent to fit body contours. The silicone-encapsulated fabrication of a thin foldable polyimide substrate with distributed surface-mount electronics is demonstrated. The measured performance results are discussed with a particular focus on the assessment of vibration-sensing elements after integration into this type of system has been described.

Large-Area Low-Cost Flexible Plastic Nanohole Arrays for Integrated Bio-Chemical Sensing

Detection of plasmonic resonance peak shifts of nano-structured metamaterials is a promising method for sensing bio-chemical binding events. Although the concept is widely demonstrated in the laboratory environment using surface nano-structures machined at low-throughput and high-costs, practical solutions for high-volume production of an integrated sensing device are very limited. We present a concept of an integrated architecture that combines a thin layer of plasmonic nanohole sensing arrays, organic light-emitting diode illumination source, and microfluidic chip, for point-of-care, field, or lab applications. We discuss the fabrication of the sensor components. In particular, we present the improved fabrication of master nano-structure replication stamps, and demonstrate outstanding results for producing singular sheets or scale up to roll-to-roll embossing of nanohole arrays on a 2000 ft production roll. We further demonstrate that nanohole arrays embossed on flexible polyethylene terephthalate plastic sheets, when coated with 100 nm thin Au metal film, are capable of generating average plasmonic resonance shifts of 180 nm refractive index unit. Hence, we report the extraordinary transmission and plasmonic resonance shifts of nanohole arrays fabricated on roll-to-roll plastic sheets for the very first time. Our results show that the embossed nano-structures on plastic are suitable as sensor elements in our proposed integrated sensor architecture, and a promising technology for low-cost disposable applications.

Context-aware physiological data acquisition and processing with wireless sensor networks

Wearable devices are a novel method for sensing physiological parameters of subjects. Even though some of them are equipped with multiple sensors, usually each parameter is analyzed separately. It often leads to false alarm generation and thus limited acceptability of these systems. We propose not only to combine multi-sensor data available on the wearable device, but also to interface the wearable nodes with a mesh network of sensing devices deployed in the environment. Such solution enables context-sensitive analysis of the physiological data leading to correct situation assessment and reliable alarm generation. The wireless sensor network provides reliable and low power communication medium for the wearable devices. We base our system on ECG and acceleration data acquired by the wearable nodes along with descriptive localization and environmental data from the wireless sensor network. We present the architecture of the proposed system and an example implementation both indoors and outdoors. The proposed system is easy to implement, flexible and scalable which makes it suitable for large area deployments.

Tungsten Lamps as an Affordable Light Source for Testing of Photovoltaic Cells

An improved Tungsten light source system for photovoltaic cell testing made from low-cost, commercially available materials is presented as an alternative to standard expensive testing equipment. In this work, spectral correction of the Tungsten light source is achieved by increasing the color temperature to ∼5200 K using inexpensive commercially available filters. Spectral measurements of the enhanced light source reveal that a better spectrum match towards the solar spectrum is achieved than what has been previously demonstrated. Specifically, the improved solar spectrum match is achieved by substantial filtering of the infrared range. The proposed setup is used to evaluate the performance of both silicon and organic based photovoltaic cells.

Optimized, practical firmware design for a novel flexible wireless multi-sensor platform for body activity and vitals monitoring

This paper proposes optimized and practical firmware development for a novel, wireless, multi-sensor, system for body activity and vitals monitoring, which improves user comfort and enables use on active mobile subjects with improved battery life1

Optimized organic photovoltaics with surface plasmons

In this work, a new approach for optimizing organic photovoltaics using nanostructure arrays exhibiting surface plasmons is presented. Periodic nanohole arrays were fabricated on gold- and silver-coated flexible substrates, and were thereafter used as light transmitting anodes for solar cells. Transmission measurements on the plasmonic thin film made of gold and silver revealed enhanced transmission at specific wavelengths matching those of the photoactive polymer layer. Compared to the indium tin oxide-based photovoltaic cells, the plasmonic solar cells showed overall improvements in efficiency up to 4.8-fold for gold and 5.1-fold for the silver, respectively.

Test firmware architecture for a flexible wireless physiological multi-sensor

This paper presents an ATE component-styled, test firmware architecture for a novel, flexible, multi-sensor for physiological monitoring. The device is fragile and the hardware components and connections must be verified for functionality before end application firmware evaluation. Additionally, the existing sensor firmware is updated to include a manufacturing test mode for additional system testing.

Towards Self-Powering Touch/Flex-Sensitive OLED Systems

In this work, we present a novel design for an organic light-emitting system integrated with a mechanical energy harvesting and energy storage polymer films (patent pending). The system is configured into multiple stacked layers to form a thin, flexible, and lightweight assembly. The thin “film-like” device can be deformed and flexed to generate energy up to 0.5 mW within 100 s with ease. This platform technology finds applications in energy harvesting displays, electronic papers, key-input-pads, novel packaging, smart-IDs, disposable lab-on-a-chip optomicrofluidic systems, and much more. Results on the energy storage characteristics of the ionic polymer-metal composite film, the performance of a polyfluorene-based organic light-emitting device, and the mechanical energy transduction of the piezoelectric polymer energy harvester are presented. The polymeric nature of this platform system further makes it suitable for roll-to-roll print manufacturing, supporting applications requiring high volume and low cost.