Developing a one-channel BCI system using a dry claw-like electrode.

An eight-class SSVEP-based BCI system was designed and demonstrated in this study. To minimize the complexity of the traditional equipment and operation, only one work electrode was used. The work electrode was fabricated in our laboratory and designed as a claw-like structure with a diameter of 15 mm, featuring 8 small fingers of 4mm length and 2 mm diameter, and the weight was only 0.1g. The structure and elasticity can help the fingers pass through the hair and contact the scalp when placed on head. The electrode was capable to collect evoked brain activities such as steady-state visual evoked potentials (SSVEPs). This study showed that although the amplitude and SNR of SSVEPs obtained from a dry claw electrode was relatively lower than that from a wet electrode, the difference was not significant. This study further implemented an eight-class SSVEP-based BCI system using a dry claw-like electrode. Three subjects participated in the experiment. Using infinite impulse response (IIR) filtering and a simplified threshold method based on fast Fourier transform (FFT), the average accuracy of the three participants was 89.3% using 4 sec-long SSVEPs, leading to an average information transfer rate (ITR) of 26.5 bits/min. The results suggested the ability of using a dry claw-like electrode to perform practical BCI applications.

A sapphire based monolithic integrated optrode.

A novel kind of optrode fabricated on a sapphire substrate is proposed for optogenetic applications in neuroscience. Eight thin-film neural electrodes and a GaN-LED are monolithically integrated on the surface of a sapphire shank. The LED is used for optogenetic stimulation and the multiple electrodes are used for simultaneous recording of neural activities. The output power density of the LED is 1-19 mW/mm2 at 468 nm, driving with a current from 0.7-10 mA. The mean electrochemical impedance of the eight recoding sites on the optrode at 1 kHz is 385 kΩ. The highest temperature-raise at tissue around the LED is almost 1 °C when the output power density is 3 mw/mm2. The monolithic integrated structure will make it a powerful tool for optogenetics.

Intraocular Pressure Sensor Based on a Contact Lens / 生物医学工程学杂志

Intraocular pressure detection has a great significance for understanding the status of eye health, prevention and treatment of diseases such as glaucoma. Traditional intraocular pressure detection needs to be held in the hospital. It is not only time-consuming to doctors and patients, but also difficult to achieve 24 hour-continuous detection. Microminiaturization of the intraocular pressure sensor and wearing it as a contact lens, which is convenient, comfortable and noninvasive, can solve this problem because the soft contact lens with an embedded micro fabricated strain gauge allows the measurement of changes in corneal curvature to correlate to variations of intraocular pressure. We fabricated a strain gauge using micro-electron mechanical systems, and integrated with the contact lens made of polydimethylsiloxane (PDMS) using injection molding. The experimental results showed that the sensitivity was 100. 7 µV/µm. When attached to the corneal surface, the average sensitivity of sensor response of intraocular pressure can be 125.8 µV/mm Hg under the ideal condition.

A wireless smart home system based on brain-computer interface of steady state visual evoked potential / 生物医学工程学杂志

Brain-computer interface (BCI) system is a system that achieves communication and control among humans and computers and other electronic equipment with the electroencephalogram (EEG) signals. This paper describes the working theory of the wireless smart home system based on the BCI technology. We started to get the steady-state visual evoked potential (SSVEP) using the single chip microcomputer and the visual stimulation which composed by LED lamp to stimulate human eyes. Then, through building the power spectral transformation on the LabVIEW platform, we processed timely those EEG signals under different frequency stimulation so as to transfer them to different instructions. Those instructions could be received by the wireless transceiver equipment to control the household appliances and to achieve the intelligent control towards the specified devices. The experimental results showed that the correct rate for the 10 subjects reached 100%, and the control time of average single device was 4 seconds, thus this design could totally achieve the original purpose of smart home system.

Effects of chain length of polyacrylic acid (PAA) on proteins adsorption of polystyrene-polyacrylic acid (PS-PAA) spherical polyelectrolyte brushes / 生物医学工程学杂志

We studied the interaction between proteins and polystyrene-polyacrylic acid (PS-PAA) spherical polyelectrolyte brushes with different polyacrylic acid (PAA) chain lengths, including the physical adsorption and chemical adsorption in PBS buffer. Results showed that the amount of bovine serum albumin (BSA) physically adsorbed on PS-PAA spherical polyelectrolyte brushes decreased to a minimum of 33 microg/mg whereas the amount of streptavidin (SA) chemically adsorbed increased with the increase of chain length and carboxyl quantity. The biotin binding capacity of streptavidin chemically adsorbed on PS-PAA spherical polyelectrolyte brushes was roughly evaluated via enzyme competitive inhibition.