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The next technological revolution, Industry 4.0, is envisioned as a digitally connected ecosystem where machines and gadgets are driven by artificial intelligence. By 2025, more than 75 billion devices are projected to serve this revolution. Many of which are to be integrated into the fabrics of everyday life in the form of smart wireless sensors. Still, two major challenges should be addressed to realize truly wireless and wearable sensors. First, the sensors should be flexible and stretchable, allowing for comfortable wearing. Second, the electronics should scavenge the energy it requires entirely from the environment, thus, eliminating the need for batteries, which are bulky, create ecological problems, etc. By addressing these two challenges, this dissertation paves the way for truly wearable sensors. The first part of the dissertation introduces a biocompatible magnetic skin with exceptional physical properties. It is highly-flexible, breathable, durable, and realizable in any desired shape and color. Attached to the skin of a user, the magnetic skin itself does not require any wiring, allowing to place the electronics and delicate components of the wireless sensor in a convenient nearby location to track the magnetic field produced by the magnetic skin. To demonstrate the performance of the magnetic skin, wearable systems are implemented as an assistive technology for severe quadriplegics, a touchless control solution for eliminating cross contaminations, and for monitoring blinking and eye movement for sleep laboratories. The second part of the dissertation is about wirelessly powering wireless sensors. In doing so, radio frequency (RF) rectifiers are a bottleneck, especially for ambient RF energy harvesting. Therefore, two RF rectifiers are introduced in standard CMOS technologies. The first architecture utilizes double-sided diodes to reduce the reverse leakage current, thus achieving a high dynamic range of 6.7 dB, -19.2 dBm sensitivity, and 86% efficiency. The second rectifier implements a dual-mode technique to lower the effective threshold voltage by 37%. Consequently, it achieves a 38% efficiency at −35 dBm input power and a 10.1 dB dynamic range while maintaining the same efficiency and sensitivity. Ultimately, combining these wireless powering techniques with the magnetic skin allows for truly wireless and wearable solutions.

Nowadays, as aging population increasing yearly, the health care technologies for elder people who commonly have high blood pressure or Glaucoma issues have attracted much attention. In order to care of those people, implantable integrated circuits (ICs) in human body are the direct solution to have 24/7 days monitoring with real-time data for diagnosis by patients themselves or doctors. However, due to the small size requirement for the implanted ICs located in human organs, it's quite challenging to integrate with transmitting and receiving antenna in a single chip, especially operating in 5.8-GHz ISM band. This research proposes a new idea to solve the issue of integrating an on-chip antenna with implanted ICs. By adding an additional dielectric substrate upon the layer of silicon oxide in CMOS technology, utilizing the metal-6, it can form an extremely compact 3D-structure on-chip antenna which is able to be placed in human eye, heart or even in a few mm-diameter vessels. The proposed 3D on-chip antenna is only 1x1x2.8 mm3 with -10 dB gain and 10% efficiency, which has capability to communicate at least within 5 cm distance. The entire implanted battery-less wireless system has also been developed in this research. A designed 30% efficiency Native NMOS rectifier could generate 1 V and 1 mA to supply the designed low power transmitter including voltage-controlled oscillator (VCO) and power amplifier (PA). The entire system performance is well evaluated by link budget analysis and the simulation result demonstrates the possibility and feasibility of future on-demand easy-to-design implantable SoC.

Implantable biomedical wireless sensors provide monitoring of vital health signs such as oxygen, temperature and intraocular pressure and may help to analyse and detect diseases in humans and animals. However, one of the design challenges of implantable devices is providing a safe and reliable energy source. Replaceable batteries are one of the most common methods for powering up implantable devices and have been used in e.g.cardiac pacemakers for decades. However, the need for a regular battery replacement may require surgical incisions. Multiple studies have been done on energy harvesting from ambient energy sources to provide the required power for the operation of the implantable sensor and thus reducing the need for battery replacement. In this work, a circuit-level radio frequency (RF) energy harvesting system has been designed and simulated in 65 nm CMOS process technology. The system consists of an AC-DC converter, a DC-DC converter, a Ring oscillator, a Buffer, and a Voltage sensor with comparators, dividers and a reference generator. The rectifier operates at a frequency of 900 MHz and offers a power conversion efficiency (PCE) of 71%. The doubler works at 50 MHz with a voltage conversion efficiency (VCE) of 98%. Additionally, the Voltage sensor monitors the voltage level of the energy-storing unit, that in this project is intended to be an mm-size rechargeable battery. If the voltage level is equal to or higher than a threshold value, Vref, the harvesting system will be in discharging mode. Similarly, if the voltage level is below Vref, then the system will be in charging mode.