Search

An integrated multiplex all-solid-state, polymer membrane-based ion-selective-electrode was designed and fabricated. The device includes an on-chip Pt pseudo-reference electrode and three independent Au working electrode. Nitrate, potassium, and phosphate selective membranes are coated on three electrodes independently. The sensitivity, selectivity, and stability of the device are evaluated using a laboratory-made measurement circuit board for ion concentrations from 10 μM to 100 mM.

Monitoring and recording of electroencephalogram (EEG) is a non-invasive procedure that is increasingly used in neuromonitoring. Patient management is assessed and tailored based on the acquired brain signals that indicates the neurological state of the patient. Conventional EEG systems are wet systems. EEG recording in itself is not painful, but scalp preparation for the electrode attachment and washing afterwards may be uncomfortable. In this paper, a soft flexible gel-free dry electroencephalogram (EEG) electrodes and dry EEG head cap is developed and proposed. The dry EEG electrodes is a hybrid packaging rigid metal snap connectors, soft and flexible polymer material, and Silver-Silver Chloride (Ag- AgCl) coating. The sensor body/ structure does not use conductive polymer and there is no peeling off of the structure that could lead to concern in signal degradation. The dry EEG head cap is a fully-adjustable one-piece stretchable material integrated with reference and ground electrodes. Impedance reading of wet system is

Extravasation is a complication of intravenous (IV) cannulation in which vesicant drugs leak from a vein into the surrounding subcutaneous tissue. The severity of extravasation depends on the type, concentration, and volume of drugs that accumulate in the subcutaneous tissue. Rapid detection of extravasation can facilitate prompt medical intervention, minimizing tissue damage, and preventing adverse events. In this study, we present two portable sensor patches, namely gold- and carbon-based sensing patches, for early detection of extravasation. The gold-based sensor patch detected extravasated fluid of volume as low as 2 mL in in vivo animal models and human clinical trials; the patch exhibited a resistance change of 41%. The carbon-based sensor patch exhibited a resistance change of 51% for 2 mL of extravasated fluid, and fabrication throughput and cost-effectiveness are superior for this patch compared with the gold-based sensing patch.

In this paper, we shall discuss the suitable alternative material to gold for creating traces or electrodes of a noninvasive flexible sensor patch that is used for detecting early extravasation during intravenous cannulation. The samples were prepared by printing $5 \mu \mathrm{m} -$ to $10 \mu \mathrm{m} -$ thin piezoresistive polymer-based Carbon paste on a base polymer patch, also called the adhesive film. The first samples have the traces embedded in between two base adhesive films. The sensitivity of the samples was characterized by using a pressure chamber/jig with 4 cm hole to mimic an extravasation by bump formation when pumped with compressed dry air (CDA) that is connected to a 15 psi source. The sensitivity value obtained was 20% up to 23% at 0.16 psi. After optimization of the curing temperature of the adhesive film and piezoresistive polymer-based Carbon traces, ex-vivo test was conducted with the prototype sample placed on the cannulation site of a pork front hock. At 2 ml and 5 ml infused fluid, the sensitivity obtained is only 1.1% and 2.44%, respectively. The overall prototype dimension of all samples is 6 × 7 cm2. The second samples were prepared with narrower trace width and spacing than the first samples. Sensitivity obtained from the second sample at 0.16 psi increased to 50% up to 79%. The third samples were prepared with the same narrow trace with as the second sample, but this time the piezoresistive polymer-based traces were not embedded in two adhesive films, making the sample a single layer patch only. Sensitivity obtained at 0.16 psi increased further to 140% up to 200%. The 0.16 psi readout is based on previous data that at this pressure induced in the 4 mm hole where the adhesive film is placed over, it translates to 3mm bump height at 2ml infused volume on the skin. The results suggest a strong potential in the development of the piezoresistive polymer-based Carbon traces for flexible non-invasive sensor patch for early extravasation detection.

Renal denervation procedure has been developed as a potential treatment for resistance hypertension or treatment-resistant hypertension. Renal denervation catheter was employed as a surgical tool to ablate the renal nerve with radio frequency (RF) pulses or ultrasound energy. Ensuring the proper contact of the electrical heater on the artery wall is critical, as excessive force or pressure could damage the artery wall. Non-contact ablation would not be able to perform the denervation operation effectively. The electrode size, overall packaging size and stiffness need to be calculated and analyzed to achieve the design for manufacturability (DFM). Ansys static structural system was used to optimize the design, the results shows that for the mini electrode with overall size of 0.6mm × 1.8 mm × 0.2 mm, 1.0mm deformation with 0.226MPa stress has a safety factor of 5 is recommended. The detailed chip level simulation shows that the force sensor chip with 150um bump has better sensitivity.

In this work, a novel hermetic packaging method using titanium and ceramic casing is proposed for long term implantable medical device. The proposed titanium-ceramic casing for implants has a better radio frequency (RF) transparency advantage as comparison to metallic materials. The proposed hermetic packaging method is used to integrate a high channels neural probe array and an active circuit module through a high density flexible cable without feedthrough integration. Hence, the profile of the integrated device achieved is as low as three millimeter and it is placed in the subdermal space. To evaluate the hermeticity of the device packaging, a helium gas leakage test was conducted and discussed. In vitro cytotoxicity test was also performed and evaluated.

Wearable electroencephalography (EEG) system can be worn for prolonged periods and have been widely used to reduce susceptibility to artifacts. It can improve localization of epileptic foci, and help doctors to optimize the treatment for patients to control epileptic seizures effectively. Commercial metal-based dry EEG sensors are capable of providing signal acquisition, however it is uncomfortable for patients since the sensor's material property is too hard to wear. In this study, design and fabrication process of dry EEG sensor are proposed for epilepsy monitoring. A medical grade silicone, Polydimethylsiloxane (PDMS), was molded as deformable substrate of the sensor. Virtual prototyping was created and simulated by ANSYS mechanical structural module. Force measurement of the fabricated sensor was conducted and discussed. The actual and simulated of sensor's stiffness were characterized and discussed.

Wire bonding is still popular and leading interconnect technologies due to its reliability, reputation for versatility and performance. Increased demand for disposal medical sensors, miniaturization for portable electronic equipment and specialty parts which are small in dimension and light weight area are at utmost importance, which lead to the chip-on-flex technology to become more attractive technology for above application. Thermo-sonic Aluminum (Al) wedge-wedge bond is preferred [1] compare to Gold (Au) bonding in most commercial chip-on-flex applications for chip to substrate interconnection due softening polymers at flexible substrate when heating at 180°C∼200°C. This softening of polymers during heating absorbs the ultrasonic energy which caused failure in ball wire bond formation on the pad/wedge, hence reducing the wire bonding yield. In this paper, we shall discuss the challenges face during Au ball bonding using polyimide flexible printed circuit board (FPCB), which has Copper as the single conductor layer and a polyimide layer. The SoC die consist of the temperature sensor, a MEMs pressure sensor, a power management unit (PMU) with an oxygen sensor together with the IC interface (Signal readout interface). The bonding temperature selection, to minimize ultrasonic energy absorption by the FPCB, the Au wire type choice used for this for successful ball bonding/wedge and the wirebonding optimization parameters involved will also be evaluated and covered. A successfully wirebonding onto the polyimide FPCB with ball shear and wire pull measurement that meet the specification will also be shown and discussed.

Intravenous cannulation (IV) has a potential medical complication known as extravasation which arise when the fluid accumulates in the subcutaneous tissue layer causing skin swelling symptom. The cost incurred for the addition hospitalization stay and treatment due to the extravasation complication is high. The current detection devices for extravasation is expensive, bulky and it is not suitable for the daily routine IV cannulation administration. In this work, a wearable and conformal sensor patch was developed for detection of skin swelling and tension. Structural simulation analysis and ex-vivo characterization of thin film metal (Ti/Cu/Au: 20 nm/ 2 µm /20 nm) were performed and result were presented in the paper. The sensor patch was able to detect skin tension and swelling of less than 3mm deformation height caused by 2-ml of fluid infusion. The sensitivity of the electrode sensor was 45% change of resistance per ml volume of infused solution.

The biopackaging of a minimally invasive sonothrombolysis device (ultrasound-assisted clot lysis device) for acute stroke treatment is proposed and presented. Instead of using thrombolytic medicine (tissue plasminogen activators) in combination with the ultrasound wave for total blood clot dissolution, the proposed sonothrombolysis device uses only pure ultrasound wave generated from Microelectromechanical Systems (MEMS)-based piezoelectric micromachined ultrasonic transducers (pMUTs) that were designed and fabricated in-house. The proposed biopackaging aims to simplify and shorten the clot lysis procedure which could help speed up the recanalization or surgical removal of the blood clots in acute ischemic stroke treatment. The device packaging is composed of two main integrated parts – the three-dimensional (3D) printed United States Pharmacopeia (USP) Class VI plastic material and the 50-µm thin polyimide flexible printed circuit board (PI FPCB) substrate. The 3D printed USP Class VI plastic material is configured as the drainage catheter of the dissolved clots as well as the custom-fit carrier of the PI FPCB substrate that is coupled and secured onto it. A single layer PI FPCB is used as the substrate of either two or four number of MEMS-based pMUTs, which are attached on it using biocompatible epoxy and wire bonded using 1 mil gold wire. The PI FPCB is also designed such that it is directly compatible with the Flat Flex Cable (FFC) connector of the external circuitry that would trigger the MEMS-based pMUTs to generate acoustic signals as well as measure the viscosity of the blood clot. To drain the dissolved blood clots, the catheter is printed with a number of holes are placed across and around the pMUT location. The catheter tip is rounded-off to remove sharp corners from the plastic material. Buckling analysis is done to simulate stiffness of the catheter when inserted into the brain tissue leading to the center of blood clot. The buckling load of the 3D printed USP Class VI plastic material at a total deformation of 0 – 1 mm at 1 sec is 2038.4N as compared to the buckling load of the silicone rubber (usual catheter material, without the metal guiding rod) which is only 0.128N. The simulation results showed that the 3D printed USP Class VI plastic material will not buckle easily during penetration in the brain tissues or insertion into the blood clot compared to silicone rubber. In order to validate that the combination of materials used in sonothrombolysis device are non-reactive and are not cytotoxic, in vitro cytotoxicity test based on ISO 10993-5 standards is performed. The materials passed.

Patients with paralysis, spinal cord injury, or amputated limbs could benefit from using brain&ndash, machine interface technology for communication and neurorehabilitation. In this study, a 32-channel three-dimensional (3D) multielectrode probe array was developed for the neural interface system of a brain&ndash, machine interface to monitor neural activity. A novel microassembly technique involving lead transfer was used to prevent misalignment in the bonding plane during the orthogonal assembly of the 3D multielectrode probe array. Standard microassembly and biopackaging processes were utilized to implement the proposed lead transfer technique. The maximum profile of the integrated 3D neural device was set to 0.50 mm above the pia mater to reduce trauma to brain cells. Benchtop tests characterized the electrical impedance of the neural device. A characterization test revealed that the impedance of the 3D multielectrode probe array was on average approximately 0.55 M&Omega, at a frequency of 1 KHz. Moreover, in vitro cytotoxicity tests verified the biocompatibility of the device. Subsequently, 3D multielectrode probe arrays were implanted in rats and exhibited the capability to record local field potentials and spike signals.

Intravenous (IV) cannulation is a routine procedure for hospital patients for drug or fluid administration. Successful delivery of drugs and fluids depends on the cannula remaining in the vein at all times. Extravasation is a complication of IV cannulation and refers to the accidental leakage of drugs or fluids from the vein to the surrounding tissues when the IV cannula moves out of the vein. The incidence of extravasation in neonates is up to 15%. Extravasation is frequently detected late when a large subcutaneous "bump" or swelling is noticed at the IV cannula site indicating a large amount of infused fluid has tissued. The severity depends on the volume/ type of drug extravasated and the time lapse before extravasation is detected. It is important to detect extravasation early to ensure that the drugs/ fluids administered will reach the patient's intravascular space otherwise it can jeopardize medical management and compromise patient care. In this work, we present a portable, practical and cost-effective sensor which can be universally applied to all patients to prevent the extravasations injuries.

In this work, we present the biopackaging andintegration method of an intracranial pressure microsystemfor multimodal neural monitoring. The neural monitoring chipused is a System-on-Chip (SoC) which hasMicroelectromechanical Systems (MEMS) capacitive pressuresensor that is fabricated in-house after Complementary Metal-Oxide Semiconductor (CMOS) wafer fabrication process, witha temperature sensor and an oxygen sensor in order to achievemultimodal neural monitoring functions. Polyimide is used forthe substrate of the SoC die and passive component due to itsbiocompatibility and flexibility. A reversed stand-off stitchwire bonding process was employed in order to achieve a lowprofilewire looping for the interconnection of the SoC die tothe substrate. The biocompatible coatings of this implantablesystem consist of Parylene-C (for covering temperature andpressure sensors), Nafion® (for covering oxygen sensor), andmedical grade silicone elastomer (for overall deviceencapsulation). The ICP microsystem wireless reader modulewas packaged in a customized biocompatible hermetic Teflonhousing. To reinforce and seal the catheter, which is integratedwith the microsystem, during the device implantation into thebrain tissue, it is filled until the wire bonded portion withpolydimethylsiloxane. Similarly, the guiding tip of the catheterwhich will facilitate the sensor device to penetrate into thebrain tissue is made and casted from a specially designed moldusing polydimethylsiloxane as the material. Verification of thepackaging feasibility was measured by measuring thesensitivities of the pressure sensor, oxygen sensor, andtemperature sensor. The whole microsystem also passed theISO 10993-5 standards in vitro cytotoxicity test with aconclusion of no reactivity and no cell lysis cell growth in cellculture, verifying its biocompatibility

Revascularization procedure for peripheral arterydisease is dependent on surgeon's skill and experience for asuccessful procedure. An integrated sensor on guidewire isproposed to reduce such dependency during the procedure. The development and packaging of the sensor with a hybridsilicone-polymer substrate (HSPS) and a silicon stopper arepresented in this paper. A compact HSPS (0.4mm x 10mm x0.31mm) with trace width/spacing of 20µm/20µm for fiveoutput signals and Si stopper with safety displacement featureto prevent force overloading are fabricated. It is able toenhanced current sensor integrated guidewire by improvingthe robustness and provides a forward sensing mechanism(orthogonal assembly). The assembled device is able tomeasure up till 42mN force with a resolution of 0.2mN. Detailof characterization testing and result will be presented in the paper.

In this work, we present an ultra-slim profile packaging and assembly solution of a 360-μm diameter medical guide wire fitted and integrated with silicon based fractional flow reserve (FFR) sensor. The miniaturization of the whole sensorized guide wire assembly without sacrificing its sensing functionality was made possible by the use of polyimide flexible printed circuit board (FPCB) as the substrate material for the silicon platform and by the use of lowest possible wire looping profile to create interconnection between the FFR sensor and the FPCB's bonding pads using the gold wires. In order to reinforce and protect the wire interfaces, as well as to maintain the required biocompatibility of the whole system, a thin layer of Polydimethylsiloxane (PDMS) was used for the encapsulation process. Long signal wires were then attached to the bonding pads of FPCB before finally fitted inside a miniaturized metal housing. This whole system has easily fit and integrated with the 360-μm diameter medical guide wire. In order to verify the packaging feasibility, the electrical short testing of the bonding pads and SEM observations were conducted.

Guidewire procedure for peripheral artery disease treatment is heavily dependent on the surgeon's skills and experiences. In order to reduce such dependency, sensor-enhanced forward sensing guidewire is proposed. In this paper, we proposed a silicon cap structure that increases the robustness and efficient force transfer of the existing sensor-enhanced forward sensing guidewire. Silicon cap structure of 0.32 × 0.32 × 0.40mm has been fabricated using two masks process. Assembly of silicon structure with sensor having a 30μm overloading protection limit and resistance changes of 25kΩ with applied force ranging from 0∼40mN has been demonstrated.

In this work, an assembled and integrated flexible probe array with biodegradable coating for stiffness control is demonstrated. The proposed method will help to overcome the stiffness issue faced by polymeric probe array during insertion into the brain tissue. It is proposed to do coating with biodegradable material to increase the stiffness of the probe shanks. Assembly process is simplified as polymer probe and cable were being monolithically fabricated, only the connector needs to be soldered onto the bonding pads. To enhance the soldering between connector and bonding pads, rigid stiffener is designed at the bonding pads region to provide robust support for soldering process and for insertion process.