Browsing by Author "Chen, Joshua C."

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    A wireless millimetric magnetoelectric implant for the endovascular stimulation of peripheral nerves
    (Springer Nature, 2022) Chen, Joshua C.; Kan, Peter; Yu, Zhanghao; Alrashdan, Fatima; Garcia, Roberto; Singer, Amanda; Lai, C.S. Edwin; Avants, Ben; Crosby, Scott; Li, Zhongxi; Wang, Boshuo; Felicella, Michelle M.; Robledo, Ariadna; Peterchev, Angel V.; Goetz, Stefan M.; Hartgerink, Jeffrey D.; Sheth, Sunil A.; Yang, Kaiyuan; Robinson, Jacob T.; Applied Physics Program
    Implantable bioelectronic devices for the simulation of peripheral nerves could be used to treat disorders that are resistant to traditional pharmacological therapies. However, for many nerve targets, this requires invasive surgeries and the implantation of bulky devices (about a few centimetres in at least one dimension). Here we report the design and in vivo proof-of-concept testing of an endovascular wireless and battery-free millimetric implant for the stimulation of specific peripheral nerves that are difficult to reach via traditional surgeries. The device can be delivered through a percutaneous catheter and leverages magnetoelectric materials to receive data and power through tissue via a digitally programmable 1 mm × 0.8 mm system-on-a-chip. Implantation of the device directly on top of the sciatic nerve in rats and near a femoral artery in pigs (with a stimulation lead introduced into a blood vessel through a catheter) allowed for wireless stimulation of the animals’ sciatic and femoral nerves. Minimally invasive magnetoelectric implants may allow for the stimulation of nerves without the need for open surgery or the implantation of battery-powered pulse generators.
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    Distributed sensor and actuator networks for closed-loop bioelectronic medicine
    (Elsevier, 2021) Bhave, Gauri; Chen, Joshua C.; Singer, Amanda; Sharma, Aditi; Robinson, Jacob T.
    Designing implantable bioelectronic systems that continuously monitor physiological functions and simultaneously provide personalized therapeutic solutions for patients remains a persistent challenge across many applications ranging from neural systems to bioelectronic organs. Closed-loop systems typically consist of three functional blocks, namely, sensors, signal processors and actuators. An effective system, that can provide the necessary therapeutics, tailored to individual physiological factors requires a distributed network of sensors and actuators. While significant progress has been made, closed-loop systems still face many challenges before they can truly be considered as long-term solutions for many diseases. In this review, we consider three important criteria where materials play a critical role to enable implantable closed-loop systems: Specificity, Biocompatibility and Connectivity. We look at the progress made in each of these fields with respect to a specific application and outline the challenges in creating bioelectronic technologies for the future.
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    Wearable wireless power systems for `ME-BIT' magnetoelectric-powered bio implants
    (IOP Publishing, 2021) Alrashdan, Fatima T.; Chen, Joshua C.; Singer, Amanda; Avants, Benjamin W.; Yang, Kaiyuan; Robinson, Jacob T.
    Objective. Compared to biomedical devices with implanted batteries, wirelessly powered technologies can be longer-lasting, less invasive, safer, and can be miniaturized to access difficult-to-reach areas of the body. Magnetic fields are an attractive wireless power transfer modality for such bioelectronic applications because they suffer negligible absorption and reflection in biological tissues. However, current solutions using magnetic fields for mm sized implants either operate at high frequencies (500 kHz) or require high magnetic field strengths (10 mT), which restricts the amount of power that can be transferred safely through tissue and limits the development of wearable power transmitter systems. Magnetoelectric (ME) materials have recently been shown to provide a wireless power solution for mm-sized neural stimulators. These ME transducers convert low magnitude (1 mT) and low-frequency (∼300 kHz) magnetic fields into electric fields that can power custom integrated circuits or stimulate nearby tissue. Approach. Here we demonstrate a battery-powered wearable magnetic field generator that can power a miniaturized MagnetoElectric-powered Bio ImplanT ‘ME-BIT’ that functions as a neural stimulator. The wearable transmitter weighs less than 0.5 lbs and has an approximate battery life of 37 h. Main results. We demonstrate the ability to power a millimeter-sized prototype ‘ME-BIT’ at a distance of 4 cm with enough energy to electrically stimulate a rat sciatic nerve. We also find that the system performs well under translational misalignment and identify safe operating ranges according to the specific absorption rate limits set by the IEEE Std 95.1-2019. Significance. These results validate the feasibility of a wearable system that can power miniaturized ME implants that can be used for different neuromodulation applications.